Thomas J Smith, M.D.

• The Harry J. Duffey Family Professor of Palliative Medicine
• Professor of Oncology

https://www.hopkinsmedicine.org/profiles/results/directory/profile/8283165/thomas-smith

This is so because underdeveloped countries lack adequate clean water supplies for drinking and proper sewage disposal systems as well as also practices poor sanitation and poor food hygiene [40 impotence quoad hanc buy generic sildigra 50mg line, 41 erectile dysfunction in diabetic subjects in italy sildigra 120 mg low price, 45 can you get erectile dysfunction pills over the counter 25 mg sildigra overnight delivery, 47] erectile dysfunction houston sildigra 25mg. Once cholera is introduced to a population in a specic location erectile dysfunction doctor new jersey purchase 120mg sildigra otc, numerous complex factors decisively inuence its propagation and may lead to prolonged transmission[70 impotence statistics order sildigra toronto, 18, 45, 41]. Socioeconomic, environmental, demographic and climatic factors enhances the vulnerability of a population to infection and contribute to the epidemic spread of cholera[40, 31, 14, 3, 56]. Poor sanitation Cholera is hypothesized as a disease of decient sanitation[2, 41, 45]. The lack of adequate toiletry, cleaning, washing and drainage facilities results in sickness and increases the risk of transmission. High poverty and low income level Borroto and Martinez-Piedra[14] and Talavera and Perez[73] identied poverty as an important predictor of cholera. Low income levels result in poor diet, malnutrition, poor housing facilities and lack of access to education. High migration this plays a role by introducing cholera into new populations[3, 31] 4. Overcrowding/high population High population will lead to overcrowding putting strain on existing sanitation systems, thereby putting the population at high risk[15, 71, 31, 51]. Lack of Clean drinking water Unsafe water supply/contaminated water will increase the risk of cholera infection[72, 45] 7. Proximity and density of refuse dumps According to Osei and Duker[59], there is a direct linear relationship between cholera prevalence and refuse dumps density and an inverse relationship with proximity to refuse dumps. Two explanations given were (1) high rate of contact with lth breeding ies;they argued that lth breeding ies serve as a carrier of the V. Proximity to surface water sources Close proximity to contaminated drinking water bodies make inhabitants more prevalent to cholera[3, 72, 60] 9. Climatic conditions Studies have shown that there is direct correlation between cholera and sea surface temperature, sea surface height, precipitation and chlorophyll concentrations[55, 21, 50]. Poor personal hygienic standards Poor personal hygiene increases cholera propagation within a given environment. In addition to human suffering and loss of lives, cholera outbreaks causes panic, disrupt socio-economic activities and can impede development in the affected communities. The spread of infectious diseases is closely associated with the concepts of spatial and spatiotemporal proximity, as individuals who are linked in a spatial and a temporal sense are at a higher risk of getting infected[62]. Spatial analysis in the nineteenth and twentieth century was mostly employed by plotting the observed disease cases or rates. For example, Snow[72] mapped cholera cases together with the locations of water sources in London, and showed that contaminated water was the major cause of the disease. Data "The objectives of spatial epidemiological analysis are the description of spatial patterns, identication of disease clusters, and explanation or prediction of disease risk"[62]. Geographic data systems include georeferenced feature data and attributes, be they points or areas. These data are obtained by taking eld surveys, remotely sensed imagery or use of existing data generated either by government organizations or those closely linked to government such as cadastral, postal, meteorological or national census statistics and health organizations. Visualization and exploration Visualization and exploration cover techniques that focus solely on examining the spatial dimension of the data. Visualization tools are used resulting in maps that describe spatial patterns and which are useful for both stimulating more complex analyses and for communicating the results of such analyses. However there is some overlap between visualization and exploration, since meaningful visual presentation will require the use of quantitative analytical methods[53]. Modeling introduces the concept of cause-effect relationships using both spatial and non-spatial data sources to explain or predict spatial patterns[62]. However, this is not a linear process, as presenting the results from exploration and modeling requires a return to visualization. Disease mapping Disease mapping provide information on a measure of disease occurrence across a geographic space. Disease maps are able to provide us a rapid visual summary of complex geographic information. These maps may also identify subtle patterns in epidemic/health data that are sometimes missed in tabular presentations[24]. Geographic correlation studies the objective of geographic correlation studies is to examine geographic disparities across inhabitants in an exposure to environmental variables which may be measured in air, water, or soil, socioeconomic and demographic measures such as race and income, or lifestyle factors such as smoking and diet in relation to health outcomes measured on a geographic scale[24]. Correlation studies deals with the association between disease risk and exposures of interest. Clustering/Cluster detection Clustering examines tendency for disease risk to exhibit "clumpiness", while the Cluster detection refers to on-line surveillance or retrospective analysis, to reveal "hot spots". The aim is to investigate disease clusters and disease incidence near a point source[46]. In his study, Snow was able to assess the spatial pattern of cholera cases in relation to potential risk factors, in this instance the locations of water pumps. He furthermore made a solid use of statistics to demonstrate the connection between the quality of the source of water and cholera incidence and used a dot map to illustrate how cases of cholera clustered around the Broad Street water pump in London (See g. These studies have been useful, in understanding the environments that are most suitable for the bacteria. To be able to identify and map environmental factors that impact risk of cholera, spatial epidemiological tools have to be applied in cholera studies. Understanding the spatial relationship between cholera and environmental risk factors have been a challenge for long. Two spatial covariates were derived and used as explanatory variables in spatial regression model to relate cholera incidence to refuse dumps in Kumasi. Spatial distance factor maps of nearest reservoirs to communities were created and used as covariates in spatial regression modeling. The areas may form a regular lattice, as with remotely sensed images, or be a set of irregular areas or zones, such as countries, districts and census zones[27]. Data about individuals are often available only at an aggregated areal level in order to protect personal information. For example, average income levels for census tracts are readily available, but the income of an individual person in that census tract is usually not available. Spatial autocorrelation statistics are used to measure and analyze the degree of spatial correlation/dependency among observations in a geographic space[28]. The principle underlying the analysis of spatial data is the proposition that values of a variable in near-by locations are more similar or related than values in locations that are far apart. This interaction could relate, for example, to spatial spillovers and externalities[46]. Spatial autocorrelation measures require a weights matrix that denes a local neighborhood around each geographic area/unit[5]. The value at each areal unit is compared with the weighted average of the values of its neighbors. Weights can be constructed based on either contiguity to the polygon boundary (shape) les, or calculated from the distance between points (points in a point shape le or centroids of polygons)[12, 78, 5]. These measures compare the spatial weights to the covariance relationship at pairs of locations. A spatial autocorrelation value observed to be positive than expected from random shows there is clustering of similar values across geographic space, while signicant negative spatial autocorrelation indicates that neighboring values are more dissimilar than expected by random, suggesting there is a spatial pattern similar to that of a chess board[5]. Global autocorrelation statistics provide a single measure of spatial autocorrelation for an attribute in a region as a whole[5]. Therefore, for non-neighboring tracts, the weight is zero, so these are not used in the calculation of correlation. These counts or rates are not continuous like the continuous outcomes familiar in linear regression. Whereas large counts or rates may roughly follow the assumptions of linear models, spatial analyses often focus on counts from small areas with relatively few subjects at risk and few cases expected during the study period. Modeling spatial interactions that arise in spatially referenced data is commonly done by incorporating the spatial dependence into the covariance structure either explicitly or implicitly via an autoregressive model. Both of these models produce spatial dependence in the covariance structure as a function of a neighbor matrix, W and often a xed unknown spatial correlation parameter[78, 77]. Moreover it includes spatial dependency in regression analysis, in which case a general model adopted is[30]: y N (X,A) (2. Now, A is chosen so that elements of y that are closer to each other in space also have higher covariance. These Spatial autoregressive models were developed primarily for use with geographically aggregated spatial data where measurements could be taken at any location in the study area in contrast to the geostatistical models developed for spatially continuous data[78]. The distribution is expressed in terms of yi i, the difference between the observed yi and the expected value of yi obtained when considering the x-variables. The former restriction means the weights must be symmetrical; the latter restriction simply means that the conditional distribution of yi cannot depend on yi itself only on other y-values. If the data are associated with a set of zones, then cij might be dened as 1 if zones i and j are contiguous, and 0 otherwise. For point data, cij might be dened as a continuous function of distance such as kdij where =1or2anddij is the distance between points i and j (assuming that there are no coincident points). This latter scheme could also be applied to zonal/area data using distances between zone centroids. In this case the marginal distributions for all the yis are specied as a system of simultaneous equations. Again, the restriction on the spatial weights that bii= 0 is imposed but there is no longer a symmetry constraint on the weight matrix. One common way to construct B or C is with a single parameter that scales a user dened neighborhood matrix W that indicates whether the regions are neighbors or not as described in Equation (2. Kumasi metropolis is one of 18 districts and capital of the Ashanti Region (See Figure 3. The rainfall pattern is bimodal with long rainy season from April to July, sometimes with peaks in May/June and a short season September and Mid-November[60]. As described by Osei[61], approximately 82% of the inhabitants in Kumasi have access to portable, pipe-borne water, however surface water from rivers and streams is still used largely for cooking, bathing and washing utensils due to rampant water shortages. Furthermore, most demarcated areas for public sanitation and waste disposal facilities have been sold out due to high demand for land compelling inhabitants to defecate at open space refuse dumps[61]. According to Osei and Duker[59], the outbreak lasted for 72 days, which was within the rainy season. The data consist of number of reported cases per community (spatial unit for reporting). Each community is represented as point shapele feature with X, Y coordinates in meters and has number of cholera cases reported in 2005, population estimates for 2005 and Raw rates as attributes. Raw rates were calculated as number of cholera cases in each community divided by the estimated population in 2005 and rescaled by multiplying it by a factor of 10,000 to express the raw rates as per 10,000 people more intuitively. The collection system of the waste management in the metropolis is based on two systems which are house-to-house waste collection and communal solid waste collection[75, 85]. The communal waste collection system consists of containers placed throughout the city (See Figure 3. The containers are being emptied by waste collection companies and transported to landll sites located in the outskirts of the metropolis in a regular basis. With house-to-house waste collection, the waste is collected at the yard or door at the households. At least 5 out of 10 household dispose of their waste right besides their houses, instead of nding the nearest waste dump[59]. Waste that is not being collected is being indiscriminately dumped in rivers (See Figure 3. The refuse dumps data consist of only point shapeles showing only the X and Y coordinates in meters. The RapidEye sensor which captured the data used for classication of the potential cholera reservoirs is briey described in the section below. Each of the ve satellites contain identical sensors, equally calibrated and travel on the same orbital plane (at an altitude of 630km). Together, the 5 satellites are capable of collecting over 4 million km2 of 5 m resolution, 5-band color imagery every day[66, 84]. Hence, radiometric, sensor and geometric corrections have been applied to the data. The shapeles when loaded into ArcMap had no coordinate system nor a reference ellipsoid. The image classication process apportions the pixels of an image to exact spectral behavior of the ground data. Pixels are sorted into a nite number of individual classes, or categories of data, based on their data le values. If a pixel satises a certain set of criteria, then the pixel is assigned to the class that corresponds to that criteria. The landuse/landcover of the study area was classied to identify water reservoirs using the RapidEye image of 2009 using the maximum likelihood algorithm. The results of the image classication were validated in order to assess their accuracy.

The results described above contribute to a literature comprised entirely of descriptive case studies (Cheney 1984; Condran 1988; Condran and Lentzner 2004) erectile dysfunction diabetes qof buy 50mg sildigra fast delivery. They also have implications for developing countries today erectile dysfunction treatment homeopathy sildigra 100mg lowest price, where climate change is expected to increase the 4 risk of diarrheal diseases (Gray 2011; Friedrich 2013; Dhimal et al erectile dysfunction doctor singapore 50mg sildigra with amex. In many parts of the world impotence workup discount sildigra 50 mg amex, diarrheal diseases still exhibit seasonality erectile dysfunction forum discussion generic 50 mg sildigra, although the intensity of this seasonality varies with region and climate (Patel et al impotence synonym trusted sildigra 25 mg. Understanding the determinants of summer diarrhea and its eventual waning could help identify effective intervention strategies as the length and intensity of seasons change across the globe 5 (Kiger 2017; Santer et al. In addition to providing the first econometric analysis on the relationship between public health interventions and diarrhea seasonality, we explore heterogeneous effects by race. Beyond the work of Troesken (2001, 2002), very little is known about how public health efforts at the th turn of the 20 century affected minorities. We show that the reduction in diarrheal mortality among black children was far less dramatic than that experienced by their white counterparts. Even towards the end of the 1920s, black diarrheal mortality exhibited strong seasonality; the diarrheal mortality rate among white children still peaked during the summer months but at less 4 In tropical climates. Although water filtration led to a reduction in non-summer diarrheal mortality among white children, it and the other public health interventions under study were essentially unrelated to diarrheal mortality among black children. We begin with an overview of diarrheal disease and a discussion of the previous literature. In Section 3, we document the summer diarrhea phenomenon using data on the 26 most populous cities in the United States as of 1910; in Section 4, we describe our empirical strategy, report our principal estimates, and consider various robustness checks; in Section 5, we explore heterogeneous effects by race. Between 500,000 and 800,000 children under the age of 5 die of diarrhea every year, most of whom are born to mothers in developing countries (Liu et al. A wide variety of bacteria, parasites and viruses cause diarrhea and other symptoms of gastroenteritis (Hodges and Gill. Infection is usually through contaminated food or water, or person-to-person contact (Pawlowski et al. In temperate climates, bacterial infections are more common during the summer (Ramos-Alvarez and Sabin 1958; Fletcher et al. In tropical climates, the incidence of diarrhea appears to peak during the rainy season (Zhang et al. Over 70 percent of total deaths from diarrhea occur among children under of the age of two (Walker et al. Susceptibility is highest at 6-11 months, presumably because exclusive 4 breastfeeding protects against infection and crawling brings children into contact with human and/or animal feces (Walker et al. Previous Literature In the decades leading up to its dissipation, summer diarrhea received a great deal of attention from physicians, who described its symptoms, noted that its victims were often born in 6 crowded tenement housing districts, and proposed various causes. For instance, one school of thought held that exposure to summer heat was directly responsible for the annual wave of diarrheal deaths among infants and children (Miller 1879; Schereschewsky 1913), while another held that overfeeding was the cause (Burg 1902; Brennemann 1908; Tilden 1909). Even among physicians who believed that summer diarrhea was caused by bacteria, there were several 7 competing theories as to the mode of transmission. Since its dissipation, only a handful of studies have examined the phenomenon of summer diarrhea. Cheney (1984) focused on the experience of Philadelphia during the period 1869-1921, while Condran (1988) focused on New York City during the period 1870-1919. These authors noted that infant mortality spiked every summer through the early 1900s, due th principally to diarrheal diseases. By the second decade of the 20 century, the phenomenon of 6 See, for instance, Miller (1879), Burg (1902), Kiefer (1902), McKee (1902), Moss (1903), Southworth (1904), Ostheimer (1905), Snyder (1906), Brennemann (1908), Murphy (1908), Tilden (1909), Stoner (1912), and Youmans and Youmans (1922). Hewitt (1910) and Youmans and Youmans (1922) argued that houseflies were the principal vector of transmission, a possibility that cannot be dismissed out of hand (Levine and Levine 1991; Forster et al. Certainly, many contemporary physicians and public health experts were convinced that 8 purifying the milk supply was key to reducing diarrheal mortality during the summer. The refrigeration chain was still missing important links during this period (Rees 2013), and bacteria such as E. It is, however, difficult to rule out the possibility that other public health measures contributed to the observed reduction. For instance, Philadelphia began the process of delivering filtered water to its residents before 1906 and began treating it with chlorine in 1910 (Anderson et al. Condran and Lentzner (2004) used data from Chicago, New Orleans, and New York for the period 1870-1917 to document the phenomenon of summer diarrhea and its waning. They found that excess mortality during the summer months fell gradually in these cities after the turn th of the 20 century, but noted that identifying the cause of this phenomenon is made exceedingly difficult by the large number of public health interventions that were undertaken at the municipal level. City-level counts of diarrheal deaths are available by month for the period 1910-1930 from Mortality 10 Statistics, which was published annually by the U. These counts include deaths due to cholera infantum, colitis, enteritis, enterocolitis, gastroenteritis, summer complaint, and other similar causes (United States Bureau of the Census 1910). In 1910, there were 21,101 diarrheal deaths among children under the age of two in the 26 most populous American cities (Figure 1), accounting for 30 percent of total mortality in this 11 age group. The reduction in diarrheal deaths during the months of June-September was even more pronounced: only 1,482 children under the age of two died from diarrhea in the summer of 1930, a reduction of almost 90 percent as 12 compared to the summer of 1910. Figure 2 shows annual diarrheal deaths among children under the age of two per 100,000 13 population. In 1910, there were 124 diarrheal deaths among children under the age of two per 9 these 26 cities are listed in Appendix Table 1. Cause of death was obtained from the death certificate and coded using the International Classification of Diseases. When more than one medical condition was listed on the death certificate, cause of death was based on a standardized algorithm (Armstrong et al. Appendix Figure 2 shows summer diarrheal deaths as a percentage of total diarrheal deaths. The summer diarrheal mortality rate fell from 82 to 6 over the same period, a reduction of 93 percent. Figure 3 shows diarrheal deaths by month among children under the age of two per 100,000 population. It is clear from this figure that seasonality waned considerably during the period under study. Other physicians agreed with Rush, asserting that the phenomenon began earlier, and lasted longer, in the South (King 1837; Copeland 1855; Condie 1858; Smith 1905). The top panel of Figure 4 shows diarrheal deaths per 100,000 population by month for the first half of the period under study. Consistent with an observation first made by Copeland 16 (1855), the diarrheal mortality rate was lower in southern, as compared to northern, cities. The bottom panel of Figure 4 shows diarrheal deaths per 100,000 population by month in northern versus southern cities for the second half of the period under study. During this later period, the monthly diarrheal mortality rate was, on average, slightly lower in northern cities, but again there is no evidence that the phenomenon of summer diarrhea began earlier or lasted longer in southern cities. However, it should be noted that only one of the cities in our sample (New Orleans, Louisiana) was located in the Deep South. During the period 1910-1920, the diarrheal mortality rate for children under the age of two in New Orleans began to climb in April and peaked in May; it peaked in June during the period 1921-1930. We explore the relationship between temperature and diarrheal mortality in Figure 6. It is not clear, however, whether such seasonality is due to temperature, humidity, changes in behavior, or host 17 susceptibility (Ahmed et al. During the last six summers I have resided and practiced medicine there, and have not seen or heard of a case of that disease. Rotavirus infections are another important cause of gastroenteritis among children under the age of 5 (Patel et al. Second, diarrheal mortality rates exhibited steady declines across all three of the temperature bands. In the next section, we explore whether the waning of summer diarrhea, documented in Figures 1-6, was related to public health interventions undertaken at the municipal level. Parasitic infections, which can also cause diarrhea, are more common in the summer months (Amin 2002). Monthly temperature variables are measured at the climate division level (there are 344 climate divisions covering the entire continental United States). Please see the following document for more details on the construction of the nClimDiv data set: ftp://ftp. Specifically, the diffusion of residential air conditioning after 1960 is related to a statistically significant and economically meaningful reduction in the temperaturemortality relationship at high temperatures. Because these authors used annual mortality data, they could not examine the determinants of seasonality. For instance, Cheney (1984) and Condran (1988) argued that efforts to purify milk supplies caused its waning, while Meckel (1990) and Fishback et al. In addition, they explored the effects of sewage treatment, projects designed to deliver clean water from further afield such as aqueducts and cribs, and municipal efforts to clean up milk supplies. He wrote: It is extremely difficult to assess with any certainty the effect that milk regulation and especially commercial pasteurization had on the urban infant death rate. Infant mortality is causally complex, and its reduction is usually tied to an amalgam of changes in the social and material environment. As one demographer has recently demonstrated, summer mortality among infants, which declined slowly between 1890 and 1910, dropped rapidly in the second decade of the century and by 1921 was all but negligible. Filtration is an indicator for whether a water filtration plant was in operation and Chlorination is an indicator for whether the water supply 23 was chemically treated. These indicators are interacted with Summer, which is equal to 1 for the months of June-September and equal to zero for the non-summer months. Demographic controls, based on information from the 1910, 1920, and 1930 Censuses (and linearly interpolated for intercensal months), are represented by the vector Xct and are listed in Table 1, along with descriptive statistics and definitions. City-level characteristics include the natural log of population and percentages of the population by gender, race, foreign-born status, and age group. City and month-by-year fixed effects are represented by the terms vc and wt, respectively. The city fixed effects control for determinants of diarrheal mortality that were constant over time, and the month-by-year fixed effects control for common shocks. Unlike water filtration, the chlorination process was simple and inexpensive: water was added to calcium hypochlorite, which was then mixed with the water supply before delivery (Hooker 1913). All regressions are weighted by city populations and standard errors are corrected for clustering at the city level (Bertrand et al. During the period 1910-1930, 8 cities adopted filtration technology, and 24 cities began treating their water with chlorine (Appendix Table 1). Filtration is associated with a 16 percent reduction in the diarrheal mortality rate during the non-summer -. By contrast, we find little evidence that filtration was effective in the months of June-September: the estimate of 2 is positive and almost 24 entirely offsets the estimate of 1. Neither the estimate of 3 nor the estimate of 4 is statistically distinguishable from zero. In the second column of Table 2, we introduce two additional municipal-level public health interventions and their interactions with the summer indicator. The first, Clean Water Project, is equal to 1 if a new aqueduct or underground tunnel was built to deliver clean water 25 (and is equal to zero otherwise). The second, Sewage Treated, is an indicator for whether the 24 the sum of these two estimates, -. With their inclusion as controls, water filtration is associated with a 17 percent reduction in the diarrheal mortality rate during the non-summer months. However, the estimated coefficients of Clean Water Project, Sewage Treated, and their interactions are not statistically significant at conventional levels. In the third and final column of Table 2, we introduce an indicator for whether city c required milk sold within its limits to meet a strict bacteriological standard. This indicator also appears on the right-hand side of the estimating equation interacted with Summer. During the period 1910-1930, 15 cities passed ordinances requiring that milk sold within their limits meet a bacteriological standard (see Appendix Table 4). Because such ordinances were difficult to meet without resorting to pasteurization (Meckel 1990, pp. See, for instance, Kesztenbaum and Rosenthal (2017) and Alsan and Goldin (forthcoming). Other cities explicitly exempted pasteurized milk from having to meet the bacteriological standard or allowed higher levels of bacteria in raw milk that was to be pasteurized before being sold. During the period 1910-1930, only two cities in our sample (Detroit and Chicago) required that all milk sold within their limits be pasteurized. Detroit passed its pasteurization ordinance in 1915 without first requiring that milk meet a bacteriological standard and that it come from tuberculin-tested cows (Kiefer 1911; Clement and Warber 1918). One year later, the Chicago commissioner of health, worried about an outbreak of Polio, ordered that all milk sold in the city be pasteurized (Czaplicki 2007). Specifically, the estimated coefficient of the bacteriological standard indicator is actually positive and statistically significant at the. By contrast, the estimated coefficient of the interaction between Bacteriological Standard and the summer indicator is negative and larger in absolute magnitude, 28 but it is not sufficiently precise to reject the null.

Although various guidelines have been established that suggest a maximal intake level of fat and fatty acids erectile dysfunction exercises dvd purchase sildigra 120 mg free shipping. Furthermore impotence guilt discount 100mg sildigra free shipping, because there may be factors other than diet that may contribute to chronic diseases impotence and depression cheap sildigra online, it is not possible to determine a defined level of intake at which chronic diseases may be prevented or may develop erectile dysfunction 2 120mg sildigra mastercard. If an individual consumes below or above this range impotence causes and symptoms buy cheap sildigra, there is a potential for increasing the risk of chronic diseases shown to affect long-term health erectile dysfunction treatment hong kong buy sildigra 100 mg mastercard, as well as increasing the risk of insufficient intakes of essential nutrients. Conversely, interventional studies show that when fat intakes are high, many individuals gain additional weight. Furthermore, these ranges allow for sufficient intakes of essential nutrients, while keeping the intake of saturated fat at moderate levels. The upper boundary corresponds to the highest intakes from foods consumed by individuals in the United States and Canada. This maximal intake level is based on ensuring sufficient intakes of essential micronutrients that are, for the most part, present in relatively low amounts in foods and beverages that are major sources of added sugars in North American diets. When assessing nutrient intakes of groups, it is important to consider the variation in intake in the same individuals from day to day, as well as underreporting. Infants consuming formulas with the same nutrient composition as human milk are consuming an adequate amount after adjustments are made for differences in bioavailability. For some nutrients, such as saturated fat and cholesterol, biochemical indicators of adverse effects can occur at very low intakes. Thus, more information is needed to ascertain defined levels of intakes at which onset of relevant health risks. A statement for health professionals from the Nutrition Committee, American Heart Association. This comprehensive effort is being undertaken by the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes of the Food and Nutrition Board, Institute of Medicine, the National Academies, in collaboration with Health Canada. See Appendix B for a description of the overall process, its origins, and other relevant issues that developed as a result of this new process. Establishment of these reference values requires that a criterion of nutritional adequacy be carefully chosen for each nutrient, and that the population for whom these values apply be carefully defined. A requirement is defined as the lowest continuing intake level of a nutrient that, for a specific indicator of adequacy, will maintain a defined level of nutriture in an individual. The median and average would be the same if the distribution of requirements followed a symmetrical distribution and would diverge if a distribution were skewed. This is equivalent to saying that randomly chosen individuals from the population would have a 50:50 chance of having their requirement met at this intake level. The specific approaches, which are provided in Chapters 5 through 10, differ since each nutrient has its own indicator(s) of adequacy, and different amounts and types of data are available for each. That publication uses the term basal requirement to indicate the level of intake needed to prevent pathologically relevant and clinically detectable signs of a dietary inadequacy. The term normative requirement indicates the level of intake sufficient to maintain a desirable body store, or reserve. Its applicability also depends on the accuracy of the form of the requirement distribution and the estimate of the variance of requirements for the nutrient in the population subgroup for which it is developed. For many of the macronutrients, there are few direct data on the requirements of children. Where factorial modeling is used to estimate the distribution of a requirement from the distributions of the individual components of the requirement (maintenance and growth), as was done in the case of protein and amino acid recommendations for children, it is necessary to add (termed convolve) the individual distributions. Examples of defined nutritional states include normal growth, maintenance of normal circulating nutrient values, or other aspects of nutritional well-being or general health. The goal may be different for infants consuming infant formula for which the bioavailability of a nutrient may be different from that in human milk. In general, the values are intended to cover the needs of nearly all apparently healthy individuals in a life stage group. Qualified health professionals should adapt the recommended intake to cover higher or lower needs. Instead, the term is intended to connote a level of intake that can, with high probability, be tolerated biologically. This indicates the need for caution in consuming amounts greater than the recommended intake; it does not mean that high intake poses no potential risk of adverse effects. In many cases, a continuum of benefits may be ascribed to various levels of intake of the same nutrient. One criterion may be deemed the most appropriate to determine the risk that an individual will become deficient in the nutrient, whereas another may relate to reducing the risk of a chronic degenerative disease, such as certain neurodegenerative diseases, cardiovascular disease, cancer, diabetes mellitus, or age-related macular degeneration. Role in Health Unlike other nutrients, energy-yielding macronutrients can be used somewhat interchangeably (up to a point) to meet energy requirements of an individual. However, for the general classes of nutrients and some of their subunits, this was not always possible; the data do not support a specific number, but rather trends between intake and chronic disease identify a range. Given that energy needs vary with individuals, a specific number was not deemed appropriate to serve as the basis for developing diets that would be considered to decrease risk of disease, including chronic diseases, to the fullest extent possible. These are ranges of macronutrient intakes that are associated with reduced risk of chronic disease, while providing recommended intakes of other essential nutrients. Above or below these boundaries there is a potential for increasing the risk of chronic diseases shown to effect long-term health. The macronutrients and their role in health are discussed in Chapter 3, as well as in Chapters 5 through 11. The amount consumed may vary substantially from day-to-day without ill effects in most cases. Healthy subgroups of the population often have different requirements, so special attention has been given to the differences due to gender and age, and often separate reference intakes are estimated for specified subgroups. People with diseases that result in malabsorption syndrome or who are undergoing treatment such as hemoor peritoneal dialysis may have increased requirements for some nutrients. Special guidance should be provided for those with greatly increased nutrient needs or for those with decreased needs such as energy due to disability or decreased mobility. Life Stage Groups the life stage groups described below were chosen while keeping in mind all the nutrients to be reviewed, not only those included in this report. Infancy Infancy covers the period from birth through 12 months of age and is divided into two 6-month intervals. Except for energy, the first 6-month interval was not subdivided further because intake is relatively constant during this time. That is, as infants grow, they ingest more food; however, on a body-weight basis their intake remains nearly the same. During the second 6 months of life, growth velocity slows, and thus daily nutrient needs on a body-weight basis may be less than those during the first 6 months of life. The extent to which intake of human milk may result in exceeding the actual requirements of the infant is not known, and ethics of human experimentation preclude testing the levels known to be potentially inadequate. It also supports the recommendation that exclusive human-milk feeding is the preferred method of feeding for normal, full-term infants for the first 4 to 6 months of life. In general, for this report, special consideration was not given to possible variations in physiological need during the first month after birth, or to the variations in intake of nutrients from human milk that result from differences in milk volume and nutrient concentration during early lactation. Because there is variation in both of these measures, the computed value represents the mean. It is assumed that infants will have adequate access to human milk and that they will consume increased volumes as needed to meet their requirements for maintenance and growth. This is because the amount of energy required on a body-weight basis is significantly lower during the second 6 months of life, due largely to the slower rate of weight gain/kg of body weight. Toddlers: Ages 1 Through 3 Years Two points were primary in dividing early childhood into two groups. First, the greater velocity of growth in height during ages 1 through 3 years compared with ages 4 through 5 years provides a biological basis for dividing this period of life. Second, because children in the United States and Canada begin to enter the public school system starting at age 4 years, ending this life stage prior to age 4 years seemed appropriate so that food and nutrition policy planners have appropriate targets and cutoffs for use in program planning. In these cases, extrapolation using the methods described in Chapter 2 has been employed. Early Childhood: Ages 4 Through 8 Years Major biological changes in velocity of growth and changing endocrine status occur during ages 4 through 8 or 9 years (the latter depending on onset of puberty in each gender); therefore, the category of 4 through 8 years of age is appropriate. The mean age of onset of breast development (Tanner Stage 2) for white girls in the United States is 10. The reason for the observed racial differences in the age at which girls enter puberty is unknown. The onset of the growth spurt in girls begins before the onset of breast development (Tanner, 1990). All children continue to grow to some extent until as late as age 20 years; therefore, having these two age categories span the period of 9 through 18 years of age seems justified. Young Adulthood and Middle-Aged Adults: Ages 19 Through 30 Years and 31 Through 50 Years the recognition of the possible value of higher nutrient intakes during early adulthood on achieving optimal genetic potential for peak bone mass was the reason for dividing adulthood into ages 19 through 30 years and 31 through 50 years. Moreover, mean energy expenditure decreases during this 30-year period, and needs for nutrients related to energy metabolism may also decrease. Adulthood and Older Adults: Ages 51 Through 70 Years and Over 70 Years the age period of 51 through 70 years spans the active work years for most adults. After age 70, people of the same age increasingly display variability in physiological functioning and physical activity. This is demonstrated by age-related declines in nutrient absorption and renal function. This variability may be most applicable to nutrients for which requirements are related to energy expenditure. Pregnancy and Lactation Recommendations for pregnancy and lactation may be subdivided because of the many physiological changes and changes in nutrient need that occur during these life stages. Moreover, nutrients may undergo net losses due to physiological mechanisms regardless of the nutrient intake. Reference Heights and Weights Use of Reference Heights and Weights Reference heights and weights are useful when more specificity about body size and nutrient requirements are needed than that provided by life stage categories. In some cases, where data regarding nutrient requirements are reported on a body-weight basis, it is necessary to have reference heights and weights to transform the data for comparison purposes. Frequently, where data regarding adult requirements represent the only available data. Besides being more current, these new reference heights and weights are more representative of the U. In addition, to provide guidance on the appropriate macronutrient distribution thought to decrease risk of disease, including chronic disease, Acceptable Macronutrient Distribution Ranges are established for the macronutrients. These reference values have been developed for life stage and gender groups in a joint U. It also provides recommendations for physical activity and energy expenditure to maintain health and decrease risk of disease. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Randomized trial of varying mineral intake on total body bone mineral accretion during the first year of life. Specific subcomponents, such as some amino acids and fatty acids, are required for normal growth and development. Other subcomponents, such as fiber, play a role in decreasing risk of chronic disease. For example, under normal circumstances the brain functions almost exclusively on glucose (Dienel and Hertz, 2001). To a large extent, the body can synthesize de novo the lipids and carbohydrates it needs for these specialized functions. An exception is the requirement for small amounts of carbohydrate and n-6 and n-3 polyunsaturated fatty acids. Of course, some mixture of fat and carbohydrate is required as a source of fuel to meet the energy requirements of the body. It was also necessary to provide quantitative guidance on proportions of specific sources of required energy based on evidence of decreased risk of disease (which, in most cases, is chronic disease). Thus, a fundamental question to be addressed when reviewing the role of these nutrients in health is, What is the most desirable mix of energy sources that maximizes both health and longevity Because individuals can live apparently healthy lives for long periods with a wide range of intakes of specific energy nutrients, it is not surprising that this optimal mix of such sources may be difficult to define. There are no clinical trials that compare various energy sources with longevity in humans. For this reason, recommendations about the desirable composition of energy sources must be based on either short-term trials that address specific health or disease endpoints, or surrogate markers (biomarkers) that correlate well with these endpoints. A large number of research studies have been carried out to examine the effects of the composition of energy sources on surrogate markers, and these have provided a basis for making recommendations. Because diets with specific ratios of carbohydrate to fat, or specific ratios of subcomponents of each, have associations with the risk of various clinical endpoints. For any given diet consumed by an individual, the sum of the contribution to energy intake as a percentage of total intake for carbohydrate, fat, protein, and alcohol must equal 100 percent. The acceptable range of macronutrient intake is a range of intakes for a particular nutrient or class of nutrients that will confer decreased risk of disease and provide the most desirable long-term health benefits to apparently healthy individuals. Basic biological research, often involving animal models, provides critical information on mechanisms that may link nutrient consumption to beneficial or adverse health outcomes.

The critical pathway provides an overview of the entire process of care without wasted time and resources erectile dysfunction protocol scam or not buy discount sildigra on-line. It includes combinations of the following: physician and nurse assessments and interventions erectile dysfunction treatment dallas texas cheap 25mg sildigra, laboratory and diagnostic tests impotence hypertension medication order cheap sildigra, treatments erectile dysfunction medscape buy sildigra in india, consultations erectile dysfunction treatment austin tx effective 120mg sildigra, activity level erectile dysfunction juicing buy sildigra line, education of the patient and family, discharge planning, and desired outcomes. A pathway amalgamates all the anticipated elements of care and treatment for a particular condition or disease. It consists of the actual clinical data and often has the form of a grid, indicating a time-scale horizontally and a list of interventions vertically (figure 1). More crucial is that the entire process of care is discussed, is made explicit and is shared by the interdisciplinary team. Because the process is made explicit, best practices can be discussed, timing and procedures can be planned and scheduled in a better way, desirable outcomes can be set and monitored, capacity and resources can be provided etc. Bandolier 26 concludes in an overview article on clinical pathways that in industry, clinical pathways would be called something else. A mix, perhaps, of good practice and quality control, plus a large helping of ongoing quality improvement. After all, care pathways involve not one action, but many, often in a complex package of care. In these complex packages, it is the combining of individual interventions in a management framework suited to local needs and abilities that is the critical factor. It requires good organization to guarantee that the right treatment is given to the right patient at the right time and in the right way. A literature search in comparing clinical pathways and guidelines was done in March 2005. The following search strategy was used: [practice guidelines and critical pathways] and [development or quality or implementation]. The searched databases were: the Cochrane Library, Medline, Cinahl and the British Nursing Index. No methodology filters were used in order to conduct a sensitive literature search. Both guideline and pathway developers usually follow a stringent framework when developing a clinical guideline 33 or a clinical pathway 34 respectively. Importantly, clinical guidelines and clinical pathways developed within a structured, coordinated programme tend to be of higher quality 35 36. Clinical guidelines usually are developed by government agencies37 38 39, institutions40 41 or expert panels42 43. One of the main reasons is that guideline development, dissemination and implementation is expensive and time-consuming 44. Nevertheless, clinical practice guidelines developed by government-supported organizations tend to be of higher quality 35. On the other hand, clinical pathways usually are local initiatives and can be used as a means of developing and implementing local protocols of care based on clinical guidelines46 39 47 or to promote the adherence to clinical guidelines 48. It is mainly done by allocating the right resources to the right patient at the right time. This local characteristic makes clinical pathways less transportable through different hospitals than clinical practice guidelines. However, since the introduction of several appraisal instruments53 the methodological quality of clinical guidelines has improved50 51 52 53 54, though other reports proof otherwise 49. A major problem with these appraisal instruments is the lack of content analysis 53, and the danger of appraising a guideline as high-quality despite its poor content. Unlike clinical practice guidelines, validated appraisal instruments for clinical pathways do not exist, nor do studies comparing the content of clinical pathways. One study reported on the development of an appraisal instrument 55 yet to be further validated. Various authors claim their clinical pathway to be evidence-based56 57 58, but the process of the systematic literature search is rarely described in detail. Once developed, a guideline has to be disseminated and implemented using appropriate strategies44. However, costs and benefits of these dissemination and implementation strategies have to be outweighed44. Many controlled trials showed the disappointing effects of various implementation strategies for clinical practice guidelines44 59 60. In contrast, because of the local development and the ownership of the development team, implementation of clinical pathways is more successful. They reported a compliance rate of physicians to the pathways of more than 90 percent ( Recent new program s are benefiting from th e m ore guideline program s program s per country adv anced m eth odology created by experienced,longstanding program s; 4. D ifferences existw ith respectto ow nersh ip and em ph asis on dissem ination and im plem entation; 5. Cluz eau instrum ent is th e m ost com plete appraisal personal instrum entand v alidated; com m unication w ith 3. Im prov em entov er tim e Validation study of instrum ent containing appraisalinstrum ent 25 item s H arpole L H etal. O f th e 880 clinicalrecom m endations abstracted from th e guidelines,only 253 (29%)w ere ev idence-based. A s agroup,th e guidelines perform ed w ellin th e scope and purpose dom ain,w ith only six guidelines (12%) scoring < 50%. For th e rem aining dom ains, h ow ev er, th e guidelines did not perform as w ell, as follow s: for stakeh older inv olv em ent, 41 guidelines (80%) scored < 50% ; for rigor of dev elopm ent, 29 guidelines (57%) scored < 50% ;for clarity and presentation,17 guidelines (33%) scored < 50% ; for applicability, 46 guidelines (90%) scored < 50% ; and for editorial independence, 47 guidelines (92%) scored < 50%. A fter considering th e dom ain scores,th e rev iew ers recom m ended only 19 of th e guidelines (37%). Seldom addressed item s w ere: potential organiz ational experts in th e field barriers and cost im plications,rev iew criteriafor m onitoring or auditpurposes,potentialconflicts ofinterest; 4. D ecision m akers need to consider th e potentialclinicalareas dev elopm ent, for clinicaleffectiv eness activ ities,th e likely benefits and costs dissem ination and req uired to introduce guidelines and th e likely benefits and im plem entation strategies costs as aresultofany ch anges in prov ider beh av iour; 3. We also conducted a hand search of the Journal of Integrated Care Pathways (2001-2005). Eleven review publications, which are frequently cited in the literature, were selected. Description of the methods for evaluating the effect of a clinical pathway: the effect of clinical pathways can be evaluated by measuring quality indicators or outcomes, by analysing variances, or by interviewing professionals and patients on their perception on pathway effectiveness. Quality indicators and outcomes can be grouped according to their focus on clinical quality, patient satisfaction, team effectiveness, efficiency or cost. Examples of tools grouping quality indicators and outcomes are the Leuven Clinical Pathway Compass 71, Balanced Scorecard 72, the Clinical Value Compass 73 and DataMap 74. In a scientific context, measuring quality indicators or outcomes for the evaluation of clinical pathways requires an appropriate design. An experimental design which is the golden standard of clinical research is not frequently used in the evaluation of clinical pathways. It is partly due by the complexity to evaluate the organizational impact of clinical pathways. It is much more difficult to randomize the multidisciplinary staff in dealing with these patient groups. Some studies are solving this issue by randomizing between hospitals or departments. This procedure doesnEt exclude however all confounding variables that are embedded in the differences between hospitals or departments. More often, a quasi-experimental design is used, carrying risks for selection bias and history and Hawthorne effects. The risk of selection bias by using a historical control group is well discussed by Trowbridge et al. In some studies, the internal validity of the design is increased by using control groups, time series designs or cross-over designs. In the pathway context, variance analysis is the in-built system for recording unexpected events which occur during patient care. These data can be used to review, update and improve clinical and organizational practices. A consensus exists in the literature on four types of variances: 1) variances due to patient needs, 2) variances due to the health care workerEs decision, 3) variances due to the system or the organization and 4) variances due to the community 77. A third method to evaluate clinical pathways is interviewing professionals and patients on their perception on pathway effectiveness. Overview of the results of evaluation studies of clinical pathways: Several studies reported on the positive effects of clinical pathways on clinical outcome. Hindle & Yazbeck 80 described positive effects on quality of care and patient outcomes for geriatric patients with depression, patients undergoing regional anaesthesia for outpatient orthopaedic surgery, pain management, neonatal intensive care, peri-operative settings, amputation, elective infrarenal aortic reconstructions, urology patients, inpatient asthma care and hip and knee arthroplasty. In contrast, Bryson & Browning 79 found very little evidence of improved outcomes. Only one of the six publications in this review reported a decreased rate of nosocomial infections81. Finally, Kwan & Sandercock 83 found that the use of stroke care pathways may be associated with positive (lower complication rate) and negative effects (quality of life). Besides the effects on clinical outcome, clinical pathways are effective in reducing the costs of care. Hindle and Yazbeck 80 reported a decrease of costs for the following conditions: acute appendicitis, aortic aneurysm surgery, treatment of alcohol withdrawal syndrome, prostatectomy, colostomies and ileostomies, outpatient tonsillectomy and adenoidectomy, acute chest pain and low-risk myocardial ischemia, peri-operative care for knee replacement surgery, total colectomy and ileal pouch/anal anastomosis, severe traumatic brain injury, gastric bypass or laparoscopic adjustable gastric banding, total hip replacement, major thoracic procedures, renal transplantation, acute exacerbations of bronchial asthma, coronary artery bypass surgery, major vascular procedures, pneumonia and decubitus ulcers. Bandolier reported an increased patient satisfaction concerning pain control after caesarean section 26. Bryson and Browning 79 found a higher satisfaction, less anxiety and better understanding in patients cared for using clinical pathways. On the other hand, Kwan and Sandercock 83 reported a significantly lower patient satisfaction in stroke patients. Hindle and Yazbeck 80 reported a positive effect on stress and frustration, improved communication and improved briefing between nurses during the change of shifts. Also, an improvement in staff education, the introduction of new staff, and collective multidisciplinary learning was reported 80. Bryson and Browning 79 found that clinical pathways were good educational tools for new staff, mainly for nurses and allied health professionals. However, a strong disagreement was found between staff members about the fact that clinical pathways improved communication 79. Finally, a positive effect on the process outcomes after the introduction of a clinical pathway in 86% of the included studies is reported. Bandolier 26 reported a reduction of the prescription of laboratory tests with 70% without an impairment of patient care. A more standardized use of antibiotics and of laboratory testing was reported by Trowbridge et. Bryson & Browning 79 reported an improved documentation in patient records and a reduction in the time spent on documentation. On the other hand, a number of health care workers in this study mentioned a reduction in the continuity of daily recording and in the detail of the record of nursing care. In the same study strong evidence was found for a decrease in duplication of documentation, leading to time benefits 79. As discussed in a previous review 84, the methodologies used to assess the effects of clinical pathways are often criticised, given the research designs and sample sizes. The goal of clinical pathways is to provide appropriate and effective health care and to reduce variation in practice 28 46. The two most commonly used methods base payment rates on the estimated actual average cost in a recent period or negotiation in the marketplace. A third method becoming increasingly common is that of basing the payment rate on the estimated cost of providing care in a cost-effective way (which might be larger or smaller than the average cost in a recent period) 93. In the context of health care, the standard cost simply is what ought to be incurred by a well-managed clinical team, allowing for all the realities including insufficient resources to deliver best-practice care. A clinical pathway obviously is a good basis for calculating the standard cost, because it has been deliberately designed to represent a good quality care in the circumstances of continual scarcity of resources. Crucial is that the cost of normal cases (which are following the pathway) is complemented with the cost of the variances such as an extra day of stay, another radiology procedure, or an additional consultation. It takes into account variations according to patient needs, choices and expectations, appropriate changes in treatment, unavoidable risks and complications, etc. As was shown earlier, there is literature on how clinical pathways can help to reduce costs and to maintain or improve the quality of care. The literature on how clinical pathways are contributing to funding or contracting is however very limited or non-existing. This is possibly due to the fact that contracting information between purchasers and providers is not frequently reported in the public domain or in the scientific literature. Whatever term is used (such as care paths, integrated clinical pathways, care maps, and anticipated recovery pathways), all try to increase efficiency by better organizing the care delivery process. As a result of early reports of critical pathway success, many institution and hospital administrators eagerly implemented pathways. There is a lack of well-designed studies analyzing the extent to which clinical pathways change clinical behaviour and patient outcomes. The vast majority of the studies describes the implementation of a pathway for a specific mostly surgical procedure and uses historical controls and poor designs. An important limitation is that the pathway treatment is not always described in detail so that differences between the experimental and control group are not easy to interpret. The development of validated, standardized clinical indicators is needed to enable the evaluation of the effects of clinical pathways in a more systematic way. Despite the uncertainties about their development, implementation and evaluation, we noticed that clinical pathway programs are disseminated rapidly in hospitals throughout the world. As many health care systems worldwide are moving to output-based payment systems. Since few studies are available in the public domain or in the scientific literature, an in-depth analysis of case-studies is recommended.

The increments in energy expenditure during digestion above baseline rates effective erectile dysfunction drugs 100 mg sildigra with mastercard, divided by the energy content of the food consumed impotence 24-year-old buy 120 mg sildigra overnight delivery, vary from 5 to 10 percent for carbohydrate impotence at 19 discount sildigra 120mg free shipping, 0 to 5 percent for fat erectile dysfunction drugs that cause purchase 25mg sildigra otc, and 20 to 30 percent for protein erectile dysfunction 10 generic sildigra 120 mg otc. Thermoregulation Birds and mammals best erectile dysfunction pills 2012 purchase sildigra 25 mg without a prescription, including humans, regulate their body temperature within narrow limits. This process, termed thermoregulation, can elicit increases in energy expenditure that are greater when ambient temperatures are below the zone of thermoneutrality. The environmental temperature at which oxygen consumption and metabolic rate are lowest is described as the critical temperature or thermoneutral zone (Hill, 1964). Because most people adjust their clothing and environment to maintain comfort, and thus thermoneutrality, the additional energy cost of thermoregulation rarely affects total energy expenditure to an appreciable extent. However, there does appear to be a small influence of ambient temperature on energy expenditure as described in more detail below. In very active individuals, 24-hour total energy expenditure can rise to twice as much as basal energy expenditure (Grund et al. The efficiency with which energy from food is converted into physical work is remarkably constant when measured under conditions where body weight and athletic skill are not a factor, such as on bicycle ergometers (Kleiber, 1975; Nickleberry and Brooks, 1996; Pahud et al. For weight-bearing physical activities, the cost is roughly proportional to body weight. In the life of most persons, walking represents the most significant form of physical activity, and many studies have been performed to determine the energy expenditures induced by walking or running at various speeds (Margaria et al. Walking at a speed of 2 mph is considered to correspond to a mild degree of exertion, walking speeds of 3 to 4 mph correspond to moderate degrees of exertion, and a walking speed of 5 mph to vigorous exertion (Table 12-1, Fletcher et al. Over this range of speeds, the increment in energy expenditure amounts to some 60 kcal/mi walked for a 70-kg individual, or 50 kcal/mi walked for a 57-kg individual (see Chapter 12, Figure 12-4). The increase in daily energy expenditure is somewhat greater, however, because exercise induces an additional small increase in expenditure for some time after the exertion itself has been completed. Taking into account the dissipation of 10 percent of the energy consumed on account of the thermic effect of food to cover the expenditure associated with walking, then walking 1 mile raises daily energy expenditure to 76 kcal/mi (69 kcal/mi 1. Since the cost of walking is proportional to body weight, it is convenient to consider that the overall cost of walking at moderate speeds is approximately 1. Energy expenditure depends on age and varies primarily as a function of body size and physical activity, both of which vary greatly among individuals. However, it is now widely recognized that reported energy intakes in dietary surveys underestimate usual energy intake (Black et al. A large body of literature documents the underreporting of food intake, which can range from 10 to 45 percent depending on the age, gender, and body composition of individuals in the sample population (Johnson, 2000). Low socioeconomic status, characterized by low income, low educational attainment, and low literacy levels increase the tendency to underreport energy intakes (Briefel et al. Ethnic differences affecting sensitivities and psychological perceptions relating to eating and body weight can also affect the accuracy of reported food intakes (Tomoyasu et al. Finally, individuals with infrequent symptoms of hunger underreport to a greater degree than those who experience frequent hunger (Bathalon et al. Reported intakes of added sugars are also significantly lower than that consumed, due in part to the frequent omission of snack foods from 24-hour food recording (Poppitt et al. Clearly, it is no longer tenable to base energy requirements on self-reported food consumption data. Thus, mean expected energy requirements for different levels of physical activity were defined. However, there are recognized problems with the factorial method and doubts about the validity of energy requirement predictions based on it (Roberts et al. The first problem is that there are a wide range of activities and physical efforts performed during normal life, and it is not feasible to measure the energy cost of each. Another concern with the factorial method is that the measurement of the energy costs of specific activities imposes constraints (due to mechanical impediments associated with performing an activity while wearing unfamiliar equipment) that may alter the measured energy costs of different activities. Although generalizations are essential in trying to account for the energy costs of daily activities, substantial errors may be introduced. Also, and perhaps most importantly, the factorial method only takes into account activities that can be specifically accounted for. However, 24-hour room calorimeter studies have shown that a significant amount of energy is expended in spontaneous physical activities, some of which are part of a sedentary lifestyle (Ravussin et al. Thus, the factorial method is bound to underestimate usual energy needs (Durnin, 1990; Roberts et al. It was originally proposed and developed by Lifson for use in small animals (Lifson and McClintock, 1966; Lifson et al. Two stable isotopic forms of water (H 18O and 2H O) are 2 2 administered, and their disappearance rates from a body fluid. However, the measurements were obtained in men, women, and children whose ages, body weights, heights, and physical activities varied over wide ranges. At the present time, a few age groups are underrepresented and interpolations had to be performed in these cases. Indeed, overfeeding studies show that overeating is inevitably accompanied by substantial weight gain, and that reduced energy intake induces weight loss (Saltzman and Roberts, 1995). Bioimpedance data were used to calculate percent body fat using equations developed by Sun and coworkers (2003). Yet no correlation can be detected between height and percent body fat in men, whereas in women a negative correlation exists, but with a very small R2 value (0. Therefore, cutoff points to define underweight and overweight must be ageand gender-specific. The revised growth charts for the United States were derived from five national health examination surveys collected from 1963 to 1994 (Kuczmarski et al. Childhood overweight is associated with several risk factors for later heart disease and other chronic diseases including hyperlipidemia, hyperinsulinemia, hypertension, and early arteriosclerosis (Must and Strauss, 1999). Similarly, overweight has been defined as above the 97th percentile for weight-forlength. For lengths between the 3rd and 97th percentiles, the median and range of weights defined by the 3rd and 97th weight-for-length percentiles for children 0 to 3 years of age are presented in Tables 5-6 (boys) and 5-7 (girls) (Kuczmarski et al. It is unlikely that body composition to any important extent affects energy expenditure at rest or the energy costs of physical activities among adults with body mass indexes from 18. In adults with higher percentages of body fat composition, mechanical hindrances can increase the energy expenditure associated with certain types of activity. Cross-sectionally, Goran and coworkers (1995a) and Griffiths and Payne (1976) reported significantly lower resting energy expenditure in children born to one or both overweight parents when the children were not themselves overweight. As such, these data are consistent with the general view that obesity is a multifactor problem. The question of whether obese individuals may have decreased energy requirements after weight loss, a factor that would help explain the common phenomenon of weight regain following weight loss, has also been investigated. Notable exceptions to the latter conclusion are from studies of Amatruda and colleagues (1993) and Weinsier and colleagues (2000), which compared individuals longitudinally over the course of weight loss with a crosssectional, never-obese control group. The combination of these data from different types of studies does not permit any general conclusion at the current time, and further studies in this area are needed. Physical Activity the impact of physical activity on energy expenditure is discussed briefly here and in more detail in Chapter 12. Given that the basal oxygen (O2) consumption rate of adults is approximately 250 mL/min, and that athletes such as elite marathon runners can sustain O2 consumption rates of 5,000 mL/min, the scale of metabolic responses to exercise varies over a 20-fold range. The increase in energy expenditure elicited while physical activities take place accounts for the largest part of the effect of physical activity on overall energy expenditure, which is the product of the cost of particular activities and their duration (see Table 12-1 for examples of the energy cost of typical activities). Effect of Exercise on Postexercise Energy Expenditure In addition to the immediate energy cost of individual activities, physical activity also affects energy expenditure in the post-exercise period. Excess postexercise O2 consumption depends on exercise intensity and duration as well as other factors, such as environmental temperatures, state of hydration, and degree of trauma, demonstrable sometimes up to 24 hours after exercise (Bahr et al. In one study, residual effects of exercise could be seen following 15 hours of exercise, but not after 30 hours (Herring et al. There may also be chronic changes in energy expenditure associated with regular physical activity as a result of changes in body composition and alterations in the metabolic rate of muscle tissue, neuroendocrine status, and changes in spontaneous physical activity associated with altered levels of fitness (van Baak, 1999; Webber and Macdonald, 2000). However, the magnitude and direction of change in energy expenditure associated with these factors remain controversial due to the variable effects of exercise on the coupling of oxidative phosphorylation in mitochondria, on ion shifts, on substrates, and on other factors (Gaesser and Brooks, 1984). Spontaneous Nonexercise Activity Spontaneous nonexercise activity has been reported to be quantitatively important, accounting for 100 to 700 kcal/d, even in subjects residing in a whole-body calorimeter chamber (Ravussin et al. Sitting without or with fidgeting raises energy expenditure by 4 or 54 percent respectively, compared to lying supine (Levine et al. This suggests that the subjects had lower levels of spontaneous movement after strenuous exercise because they were more tired. Similarly, Blaak and coworkers (1992) reported no measurable change in spontaneous physical activity in obese boys enrolled in an exercise-training program. The combination of these different results indicates that the effects of planned physical activity on activity at other times are highly variable (ranging from overall positive to negative effects on overall energy expenditure). This most likely depends on a number of factors, including the nature of the exercise (strenuous versus moderate), the initial fitness of the subjects, body composition, and gender. Gender There are substantial data on the effects of gender on energy expenditure throughout the lifespan. Although the energy requirement for growth relative to maintenance is low, except for the first months of life, satisfactory growth is a sensitive indicator of whether energy needs are being met. The energy cost of growth as a percentage of total energy requirements decreases from around 35 percent at 1 month to 3 percent at 12 months of age, and remains low until the pubertal growth spurt, at which time it increases to about 4 percent (Butte, 2000). Infants double their birth weight by 6 months of age, and triple it by 12 months (Butte et al. Progressive fat deposition in the early months results in a peak in the percentage body weight that is fat at 3 to 6 months (about 31 percent) and body fatness subsequently declines to an average of 27 percent at 12 months (Butte et al. During infancy and childhood, girls grow slightly slower than boys, and girls have slightly more body fat (Butte et al. During adolescence the gender differences in body composition are accentuated (Ellis, 1997; Ellis et al. Growth velocity is a sensitive indicator of energy status and use of growth velocity charts will detect growth faltering earlier than detected using attained growth charts. Problems with measurement precision and high variability in individual growth rates over short time periods complicate the interpretation of growth velocity data. The timing of the adolescent growth spurt, which typically lasts 2 to 3 years, is also very variable, with the onset typically between 10 and 13 years of age in the majority of children (Forbes, 1987; Tanner, 1955). In general, weight velocity reflects acute episodes of dietary intake, whereas length velocity is affected by chronic factors. The suggested breakpoint for a more rapid decline apparently occurs around 40 years of age in men and 50 years of age in women (Poehlman, 1992, 1993). All of these determinants of energy requirements are potentially influenced by genetic inheritance, with transmissible and nontransmissible cultural factors contributing to variability as well. Currently there is insufficient research data to predict differences in energy requirements among specific genetic groups, but as data accumulate this may become possible. The effects of genetic inheritance on body composition are well known, with most studies reporting that 25 to 50 percent of interindividual variability in body composition can be attributed to genetic factors (Bouchard and Perusse, 1993). The same group also reported that there is a genetic component to the weightgain response to 1,000 kcal/d of overfeeding (Bouchard et al. These studies are consistent with the reports of lower levels of reported physical activity in African-American versus Caucasian adults (Washburn et al. Other Ethnic Groups In addition to African Americans and Caucasians, other ethnic groups have been investigated for potential differences in energy requirements. Similarly, physical activity levels were not different between Pima Indian and Caucasian children (Salbe et al. Thus, there are currently insufficient data to define specific differences in energy requirements between different racial groups and more research is needed in this area. The question of whether normal variations in ambient temperature influence energy requirements is therefore complex. Ambient temperature effects are probably only significant when there is prolonged exposure to substantial cold or heat. The energy cost of work was judged to be 5 percent greater in a cold environment as compared to a warm environment (Consolazio et al. There can also be an additional energy cost (2 to 5 percent) of both the increased weight of clothing worn and the hobbling effect of that clothing in cold weather compared with clothing worn in warm weather (Consolazio et al. In addition, temperatures low enough to induce shivering or increased muscular activity will increase energy needs because of the increase in mechanical work (Timmons et al. More recent work also suggests that the recognized increase in energy expenditure in markedly cold climates may be greater in physically active individuals than in sedentary ones (Armstrong, 1998). There is an increase in the energy expenditure of standard tasks when ambient temperatures are very high (Consolazio et al. However, this increase in energy expenditure may be attenuated by continued exposure. More recent studies have reported a significant effect of variations in ambient temperature within the usual range on energy requirements. Instead, the effect of ambient temperature appears to be confined to the period of time during which the ambient temperature is altered. Nevertheless, the energy expenditure response to cold temperatures may be enhanced with previous acclimatization by prolonged exposure to a cool environment (Kashiwazaki et al. Since most of the recent data has been collected in women, further research in this area is needed. There was also no significant difference in season-related values for physical activity in free-living adult Dutch women, but in contrast to the values reported above for soldiers, the values tended to be higher in summer than in winter (van Staveren et al.

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