Barbara A. Bowman

Prevention of chronic disease in the 21st century: elimination of the leading preventable causes of premature death and disability in the USA

With non-communicable conditions accounting for nearly two-thirds of deaths worldwide, the emergence of chronic diseases as the predominant challenge to global health is undisputed. In the USA, chronic diseases are the main causes of poor health, disability, and death, and account for most of health-care expenditures. The chronic disease burden in the USA largely results from a short list of risk factors--including tobacco use, poor diet and physical inactivity (both strongly associated with obesity), excessive alcohol consumption, uncontrolled high blood pressure, and hyperlipidaemia--that can be effectively addressed for individuals and populations. Increases in the burden of chronic diseases are attributable to incidence and prevalence of leading chronic conditions and risk factors (which occur individually and in combination), and population demographics, including ageing and health disparities. To effectively and equitably address the chronic disease burden, public health and health-care systems need to deploy integrated approaches that bundle strategies and interventions, address many risk factors and conditions simultaneously, create population-wide changes, help the population subgroups most affected, and rely on implementation by many sectors, including public-private partnerships and involvement from all stakeholders. To help to meet the chronic disease burden, the US Centers for Disease Control and Prevention (CDC) uses four cross-cutting strategies: (1) epidemiology and surveillance to monitor trends and inform programmes; (2) environmental approaches that promote health and support healthy behaviours; (3) health system interventions to improve the effective use of clinical and other preventive services; and (4) community resources linked to clinical services that sustain improved management of chronic conditions. Establishment of community conditions to support healthy behaviours and promote effective management of chronic conditions will deliver healthier students to schools, healthier workers to employers and businesses, and a healthier population to the health-care system. Collectively, these four strategies will prevent the occurrence of chronic diseases, foster early detection and slow disease progression in people with chronic conditions, reduce complications, support an improved quality of life, and reduce demand on the health-care system. Of crucial importance, with strengthened collaboration between the public health and health-care sectors, the health-care system better uses prevention and early detection services, and population health is improved and sustained by solidifying collaborations between communities and health-care providers. This collaborative approach will improve health equity by building communities that promote health rather than disease, have more accessible and direct care, and focus the health-care system on improving population health.

Serum Total Homocysteine Concentrations in the Third National Health and Nutrition Examination Survey (1991-1994): Population Reference Ranges and Contribution of Vitamin Status to High Serum Concentrations

Homocysteine, a non-protein-forming sulfur amino acid, has attracted attention because elevated concentrations of circulating total homocysteine are associated with an increased risk for vascular disease (1, 2). Homocysteine is also a sensitive functional marker of inadequate cellular folate and vitamin B12 concentrations (3). Inadequate status of these vitamins has important health consequences that may be independent of their role in homocysteine metabolism. Low folate concentrations increase a womans risk for having a baby with a neural tube defect (4, 5), and an inadequate vitamin B12 concentration is known to produce various neurologic and cognitive effects (6, 7). Persons with low circulating folate or vitamin B12 concentrations have higher fasting total homocysteine concentrations (8-10), and elevated fasting total homocysteine concentrations are usually normalized by treatment with folic acid and vitamin B12 (6, 11-14). However, less is known about the importance of these vitamins as risk factors for high homocysteine concentration in the general population. Only three studies have examined the relation between homocysteine concentration and its vitamin determinants in samples that were designed to be representative of U.S. national (8) or regional (9, 10) populations. One of these studies (9) reported that approximately two thirds of all cases of moderately elevated total homocysteine concentrations were potentially attributable to low vitamin concentrations, but estimation of the proportion of cases with high homocysteine concentrations that can be attributed to inadequate vitamin status is complicated by the lack of a standard definition of a high total homocysteine concentration. In the absence of a definition based on increased risk for an adverse health outcome, such as vascular disease, upper reference limits from samples of healthy persons without established risk factors for high homocysteine concentrations have been used to define a high total homocysteine concentration (10, 15-17). We previously described the distribution of total serum homocysteine concentrations in participants 12 years of age or older from the third National Health and Nutrition Examination Survey (NHANES III), a population-based sample of U.S. residents (18). These data present a unique opportunity to develop population reference ranges for serum total homocysteine concentration and to determine the extent to which elevated homocysteine concentrations are associated with low circulating vitamin concentrations in a representative sample of U.S. residents. Methods Participants The NHANES III was developed to obtain nationally representative information on the health and nutritional status of the civilian, noninstitutionalized U.S. population (19, 20). Homocysteine concentrations were measured as part of an NHANES III surplus sera project on serum samples from participants 12 years of age or older who were seen during phase II of this survey (19911994). This project is described in greater detail elsewhere (18). Homocysteine concentrations were measured at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University by using the high-performance liquid chromatography method of Araki and Sako (21). The interassay coefficient of variation for this assay was 6%. Folate and vitamin B12 were determined for phase 2 specimens at the Centers for Disease Control and Prevention central laboratory by using a Quanta Phase II radioassay kit (Bio-Rad Laboratories, Hercules, California), and analyses are described in detail in the NHANES III Laboratory Procedures Manual (22). The coefficients of variation for folate and vitamin B12 were 6% and 7%, respectively. Informed consent was obtained from all respondents. The NHANES III protocol was approved by the National Center for Health Statistics NHANES Institutional Review Board, and measurement of serum homocysteine was approved by the Human Investigations Review Committee at the New England Medical Center. We used the following search strategy, combining Medical Subject Headings (MeSH terms) and text words, to identify all population-based studies relating vitamin status to circulating homocysteine concentrations: ([homocysteine (MeSH] OR homocysteine [Text Word]) AND (vitamins [MeSH] OR vitamin [Text Word]]) AND (epidemiologic studies [MeSH] OR data collection [MeSH] OR survey [Text Word]]. This search identified 137 citations, of which 16 were reviews. We selected original studies that 1) were designed to be representative of national, regional, or local populations and 2) described the relation between circulating homocysteine concentrations and either intake or circulating concentrations of folate or vitamin B12. As of 1 March 1999, 3 articles met our criteria (8-10). Statistical Analysis We used sample weights in analyses to account for unequal probability of selection and nonresponse and to produce estimates of means and percentiles that were representative of the noninstitutionalized, civilian U.S. population. We used SUDAAN statistical software (23) to account for the complex survey design in the variance estimates. Because total homocysteine, folate, and vitamin B12 values were skewed, logarithmic transformations were applied. To show the relations between total homocysteine concentrations and vitamin concentrations, we classified participants into age- and sex-specific vitamin decile categories and estimated the geometric mean of the serum total homocysteine concentration within each decile. Analyses were adjusted for ethnicity and serum creatinine concentration. In addition, the relation between total homocysteine and folate concentrations was adjusted for vitamin B12 concentrations, and the relation between total homocysteine and vitamin B12 was adjusted for folate concentrations. We tested the associations between homocysteine and vitamins for interactions with age, sex, and ethnicity. We tested for trend of total homocysteine concentration across vitamin concentrations by using linear regression with the logarithm of the continuous vitamin concentration as the independent variable, adjusting as described above. We showed the trend by using the SYSTAT LOWESS procedure to fit smoothed curves (24) to the geometric mean total homocysteine concentrations in the vitamin decile categories (25). It has been suggested that population reference ranges for the total homocysteine concentration be established in samples of persons without established risk factors for a high homocysteine concentration (10, 15-17). For our reference sample, we included persons whom we assumed to be folate- and vitamin B12-replete (that is, their serum concentrations of both vitamins were above the 50th percentile) and had normal serum creatinine concentrations (<90 mol/L for women and<110 mol/L for men). Pregnant women were excluded. We used the 5th and the 95th percentiles from the reference sample to estimate population reference ranges. To identify the potential impact of low vitamin concentrations on high total homocysteine concentration, we needed to establish values for high total homocysteine and low vitamin concentrations. We used the sex-specific 95th percentiles in the participants 20 to 39 years of age (the reference sample) to define high total homocysteine concentrations for all age groups. We used this reference sample because homocysteine concentrations changed little with age in this group, unlike in the other age groups (18). We defined low vitamin concentrations as a folate concentration less than 11 nmol/L (26, 27) and a vitamin B12 concentration less than 185 pmol/L (28, 29). We calculated the prevalence of high total homocysteine concentration; the prevalence ratio for high total homocysteine concentration; the attributable risk percentage; and the population attributable risk percentage for persons with low concentrations of folate, vitamin B12, or both compared with persons who had adequate concentrations of both of these vitamins. The attributable risk percentage estimates the excess cases of high homocysteine concentrations among persons with low vitamin concentrations, whereas the population attributable risk percentage takes into account the prevalence of low vitamin concentrations in the population and estimates the excess of high homocysteine concentrations associated with low vitamin concentrations in the entire population. We used the design effect for total homocysteine concentration, which is the ratio of the complex sampling design variance derived by using SUDAAN software (23) to the simple random sample variance calculated by using SAS software (30), to determine the recommended minimum sample size needed to achieve stable estimates of means, proportions, and percentiles according to the National Center for Health Statistics analytic guidelines (19). On the basis of an average design effect of approximately 1.4 for our sample, means and medians derived from fewer than 42 participants, 10th and 90th percentiles derived from fewer than 112 participants, and 5th and 95th percentiles derived from fewer than 224 participants were deemed unstable. Sample size for stable estimates of the proportions varied by the magnitude of the proportion, ranging from 42 for proportions of 0.5 to 224 for proportions of 0.05 or 0.95. We indicate in the text and tables statistics that did not meet the appropriate sample size. We categorized participants into three ethnic groups: non-Hispanic white, non-Hispanic black, and Mexican American. We excluded persons from other ethnic groups (n=436) because their inclusion produced unstable estimates of mean total homocysteine concentration after adjustment for ethnicity. Our analyses are based on 8086 participants with complete data on serum total homocysteine, folate, vitamin B12, and creatinine concentrations. Results Table 1 shows selected characteristics of the sample by sex and ethnic group. On average, non-Hispanic white pa

Trends in fruit and vegetable consumption among adults in 16 US states: behavioral risk factor surveillance system, 1990-1996.

OBJECTIVES This study examined trends in fruit and vegetable consumption among adults in 16 US states. METHODS Data from telephone surveys were used to stratify respondents by sociodemographic and health-related characteristics. RESULTS The proportion of adults who consumed fruits and vegetables at least 5 times daily was 19%, 22%, and 23% in 1990, 1994, and 1996, respectively. While the proportion increased among those with active leisure-time physical activities and normal weight, it remained almost the same among inactive people and dropped among the obese. CONCLUSIONS Progress in fruit and vegetable intake from 1990 to 1994 was encouraging, but it changed little between 1994 and 1996.

Serum selenium levels in the US population: Third National Health and Nutrition Examination Survey, 1988-1994.

The published literature on serum selenium levels in the US population describes studies on small samples that may not be representative of the US population. This analysis provides the first nationally representative serum selenium levels in the US population by age group, sex, race-ethnicity, poverty income ratio (PIR), geographic region, and urban status. The Third National Health and Nutrition Examination Survey (NHANES III) is a national population-based cross-sectional survey with an in-person interview and serum selenium measurements.For the 18,597 persons for whom serum selenium values were available in NHANES III, the mean concentration was 1.58 µmol/L and the median concentration was 1.56 µmol/L. Mean serum selenium levels differed by age group, sex, race-ethnicity, PIR, and geographic region. The US population has slight differences in serum selenium levels by demographic factors.

Levels and correlates of LDL and VLDL particle sizes among children: the Bogalusa heart study.

Levels of lipids and lipoproteins among children vary by sex and race/ethnicity, and are correlated with age, obesity, and other characteristics. There is, however, little information on the distribution and correlates of low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) subclasses in early life. We used nuclear magnetic resonance (NMR) spectroscopy to determine mean LDL and VLDL particle sizes among 10- to 17-year-olds (n=918) who participated in the 1992-94 examination of the Bogalusa heart study. As compared with girls, boys had a smaller (0.1 nm) mean LDL particle size and a larger (0.9 nm) mean VLDL size; furthermore, the average size of VLDL particles increased with age among white boys but not among other children. Although there were also black/white differences in particle sizes, with black children having larger LDL and smaller VLDL particles, these racial contrasts could be attributed to differences in lipid levels. Levels of triglycerides, insulin, and relative weight were associated with the size of VLDL (positive) and LDL (negative) particles. These results suggest that the analysis of lipoprotein subclasses may provide a better understanding of the role of various risk factors in the development of coronary heart disease

Serum Ferritin Iron, a New Test, Measures Human Body Iron Stores Unconfounded by Inflammation

Serum ferritin protein is an acute phase reactant. We hypothesized that serum ferritin protein generated in response to an inflammatory process would have much less iron (Fe) in it than would “normal” ferritin protein, and therefore measuring serum ferritin iron would assess human body iron status unconfounded by inflammation.

Use of prescription weight loss pills among U.S. adults in 1996-1998.

The prevalence of obesity has increased markedly in the United States (1), as has approval of weight loss drugs by the U.S. Food and Drug Administration (FDA). In 1959, the FDA approved phentermine, the first prescription appetite suppressant used as a single-drug, short-term treatment for obesity. The FDA approved fenfluramine in 1973 for single-drug, short-term use and dexfenfluramine in 1996 as a single-drug, prescription appetite suppressant for longer-term use in obese persons. From 1995 to mid-1997, fenfluramine or dexfenfluramine was widely used in combination with phentermine (fen-phen), often for periods longer than a few weeks (2). After numerous reports of cardiac valvulopathy in persons taking fenfluramine or dexfenfluramine (3), the FDA issued a public health advisory on 8 July 1997 (4) that led to the voluntary withdrawal of the drugs from the U.S. market on 15 September 1997. The U.S. Department of Health and Human Services estimated that between 1995 and 1997, 1.2 to 4.7 million persons in the United States used fenfluramine and dexfenfluramine (3). These figures, however, were not based on population surveys but were indirectly estimated from the number of prescriptions written, with assumptions about the median duration of treatment and mean length of a prescription (5). Thus, the extent to which the population has been exposed to prescription weight loss drugs remains uncertain. In addition, no data were available on the characteristics of persons using the drugs or on whether the drugs were used in accordance with the pharmacotherapy guidelines suggested by the FDA and the 1998 National Heart, Lung, and Blood Institute consensus statement (6, 7). The purpose of our study was to provide estimates of the 19961998 prevalence of the use of prescription weight loss drugs by age, race or ethnicity, and sex by using data from a telephone survey in a sample of U.S. adults. Methods We examined data from the 1998 Behavioral Risk Factor Surveillance System (BRFSS), a telephone survey of health practices of adults 18 years of age and older conducted by all U.S. state health departments. Each state, the District of Columbia, and Puerto Rico selected an independent probability sample of noninstitutionalized residents through random-digit dialing; the results were pooled for statistical analyses (Schulman J. Can BRFSS data be pooled for national estimates? Presented at the Sixteenth Annual Behavioral Risk Factor Surveillance System Conference, Minneapolis, Minnesota, 16 May 1999). In 1998, 149 806 persons responded to the BRFSS. (A detailed description of survey methods and quality control indices has been published elsewhere [8].) In 1998, the median upper-bound response rate for individual states (completed interviews divided by completed, refused, and terminated interviews) was 73.4% (range, 45.4% to 95.4%). Body mass index (BMI) at the time of survey completion (current use) and before use of weight control pills was calculated as the self-reported weight in kilograms divided by height in meters squared and was categorized in five groups: normal weight (<25 kg/m2); preobesity (25 to 29 kg/m2), obesity grade I (30 to 34 kg/m2), obesity grade II (35 to 39 kg/m2), and obesity grade III ( 40 kg/m2) (7). According to guidelines of the FDA and National Heart, Lung, and Blood Institute, pharmacotherapy may be considered for persons who are clinically obese (body mass index 30 kg/m2) or have a body mass index between 27 and 30 kg/m2 plus an obesity-related comorbid condition (for example, hyperlipidemia, hypertension, diabetes, or cardiovascular disease) (6, 7). Because the BRFSS survey did not collect complete information on comorbid conditions, we conservatively defined inappropriate pill use as reported use of weight loss pills in a person with a body mass index less than 27 kg/m2 before pill use. Of the 149 806 respondents, we excluded those who did not report on pill use (1561 persons), weight before pill use (487 persons), current weight (5229 persons), height (1369 persons), pregnancy status (1780 persons), or sociodemographic characteristics or weight loss behavior (964 persons). We also excluded 88 respondents because the reported weight, height, or body mass index was outside the sex-specific reference values from the Third National Health and Nutrition Examination Survey, 19891994 (9). After exclusions, our study sample consisted of 139 779 respondents. To perform statistical analyses, we used SUDAAN software (Research Triangle Institute, Research Triangle Park, North Carolina), which could accommodate our complex sampling design (10). Survey weights were used to produce U.S. population estimates. Results In 19961998, an estimated 2.5% (95% CI, 2.3% to 2.7%) of U.S. adults used prescription weight loss pills (Table 1). The 2-year prevalence was four times higher among women (4.0%) than men (0.9%) and was one third higher among Hispanic respondents (3.2%) than non-Hispanic white (2.4%) or non-Hispanic black (2.4%) respondents. Among men, pill use was highest in respondents 35 to 64 years of age, and among women, pill use was highest in those aged 25 to 44 years. Table 1. Two-Year Prevalence of Use of Prescription Weight Loss Pills among U.S. Adults Use of prescription weight loss pills increased with current body mass index (Table 1). Among women, the 2-year prevalence of pill use was lowest (1.5% [95% CI, 1.3% to 1.7%]) in those with a current body mass index less than 25 kg/m2 but was substantially higher (17.7% [CI, 15.2% to 20.2%]) in those with a current body mass index of 40 kg/m2 or greater. A similar relationship between pill use and current body mass index was observed among men but with consistently lower values (range, 0.2% to 9.1%). The sex-specific pattern of pill use for current body mass index was similar for all racial and ethnic groups (Table 1). Overall, prescription weight loss pills were used by 3.1% (CI, 2.5% to 3.7%) of obese (body mass index 30 kg/m2) men and 10.2% (CI, 9.4% to 11.0%) of obese women. In an analysis restricted to persons who reported use of prescription weight loss pills (n=3822), we found that 56.1% (CI, 53.5% to 58.7%) of this group were obese before using these pills (Table 2). However, 25.3% (CI, 22.9% to 27.7%) were below the minimum recommended body mass index of 27 kg/m2. Among persons with a body mass index less than 27 kg/m2, pill use was twice as likely among women as men (27.9% [CI, 25.1% to 30.7%] vs. 13.2% [CI, 11.2% to 15.2%]) and almost twice as likely among non-Hispanic white and Hispanic respondents (26.1% [CI, 24.7% to 27.5%] vs. 26.4% [CI, 22.9% to 29.9%]) as non-Hispanic black respondents (15.0% [CI, 12.2% to 17.8%]). Table 2. U.S. Adults Who Used Prescription Weight Loss Pills, according to Body Mass Index before Pill Use At the time of the survey, 0.5% ([CI, 0.48% to 0.52%]) of respondents were currently using prescription weight loss pills. Paralleling the 2-year prevalence of pill use, the rate for current reported use in women (0.8% [CI, 0.6% to 1.00%]) was fourfold that of men (0.2% [CI, 0.18% to 0.22%]). Except for a peak in current use in October (1.0% [CI, 0.96% to 1.04%]), little seasonal or monthly variation was seen in pill use during 1998 (range, 0.4% to 1.0%). Discussion From this population-based study, we estimate that 4.6 million U.S. adults used prescription pills for weight loss in 19961998. Women were four times as likely as men to report pill use. Reported use was similar in white and black respondents but was about one third higher among Hispanic respondents than in white and black respondents. Although Hispanic persons have shown a greater inclination toward antibiotic use compared with non-Hispanic persons (11), without more information we cannot speculate on reasons for the higher use of weight loss pills among Hispanic respondents in the current study. Pill use increased with increasing body mass index and was three times higher among obese women than obese men. Among severely obese respondents (body mass index 40 kg/m2), the rate of pill use was nearly twice as high in women as men. Reported use of prescription weight loss pills was also substantial among adults who were not obese. In our analysis, we used a conservative definition of appropriate pill usea body mass index of 27 kg/m2 or greater. We estimate that one eighth of men and more than one fourth of women who used prescription weight loss pills in 19971998 had a pre-pill body mass index less than the minimum body mass index of 27 kg/m2 suggested in the FDA and National Heart, Lung, and Blood Institute guidelines. Thus, we estimate that at least 1.2 million adults may have inappropriately used pills in that period. Inappropriate pill use was substantially higher among non-Hispanic white and Hispanic respondents than non-Hispanic black respondents. Our analysis is limited by the lack of information on the specific prescription drugs used, duration of drug use, dosage, and weight loss during use of the drug. Because the Behavioral Risk Factor Surveillance System did not ask about drugs used concurrently with prescription weight loss pills, no conclusions can be made about the potential for adverse effects or drug interactions. Self-reported weight may also be a concern because many people, especially those who are relatively heavy, may under-report their weight (12, 13). Although the number of pills prescribed may have decreased immediately before the survey, no data are available for prevalence by month in 1997. However, the prevalence of current use throughout 1998 did not vary by month or season, except in October 1998, which was nearly 1 year after the public advisory on fenfluramine and dexfenfluramine. Our data indicate that one quarter of U.S. adults who use prescription weight loss pills were not overweight when the pills were prescribed. Other data suggest that more than one third of overweight persons do not meet recommendations for physical activit

Dietary Sodium and Cardiovascular Disease Risk--Measurement Matters.

The benefit of reducing dietary sodium for lowering the risk of cardiovascular disease has been questioned because some studies have also linked low sodium intake with increased CVD risk. Application of Hills criteria, however, indicates that the association is not causal.

Changes in health behaviors among older Americans, 1990 to 2000

Objectives. The authors used a large population-based survey to examine changes from 1990 to 2000 in age distribution by sex and race or ethnicity, to estimate both state-specific and national trends in the proportion of older Americans, and to examine changes in risk factors and quality-of-life indicators among those Americans. Methods. The Behavioral Risk Factor Surveillance System (BRFSS), a cross-sectional telephone survey of adults aged ≥18 years. BRFSS data were analyzed for the District of Columbia and all states that participated from 1990 to 2000. SAS and SUDAAN were used in the analyses to account for the complex sampling design. Results. The percentage of Americans aged ≥75 years increased 23.0% from 1990 to 2000, with the magnitude of the increase varying by state. In 2000, Florida had the highest percentage of persons aged ≥75 (10.27%) and Alaska the lowest (3.49%). Compared with 1990, older Americans in 2000 were more likely to be obese (16.3% vs. 13.5%) or diabetic (14.3% vs. 11.0%). Older Americans in 2000 were also more likely to exercise, consume more fruits and vegetables daily, and to have recently obtained a routine medical checkup. In addition, they were less likely to smoke tobacco or drink any alcohol. Conclusions. Increases in the population of older people will have a tremendous impact on health care in the states and will affect their future plans for serving the elderly. Although older Americans are living more healthfully than previously, there is an enormous need for targeted health promotion programs to prevent chronic diseases in this age group.

Assessment of Infant Feeding: the Validity of Measuring Milk Intake

Accurate assessment of infant feeding is needed for clinical practice and research. We identified 32 studies that evaluated the validity of direct observation, test weighing, or doubly labeled water methods. Correlations with validation standards were highest for doubly labeled water and test weighing, and lowest for observation. Cost and availability of isotope may limit the doubly labeled water method to research studies, whereas observation may be useful for clinical practice. Test weighing could be applied to either setting, but it may be practical to sample less frequently over 24 hours. Validity results and intended use of the measurement should be considered when selecting a method.