Michele Casper

Association of the Insulin Resistance Syndrome and Microalbuminuria among Nondiabetic Native Americans.The Inter-Tribal Heart Project

This study investigated the association between microalbuminuria and the insulin resistance syndrome (IRS) among nondiabetic Native Americans. In a cross-sectional survey, age-stratified random samples were drawn from the Indian Health Service clinic lists for one Menominee and two Chippewa reservations. Information was collected from physical examinations, personal interviews, and blood and urine samples. The urinary albumin:creatinine ratio (ACR) was measured using a random spot urine sample. The IRS was defined by the number of composite traits: hypertension, impaired fasting glucose (IFG), high fasting insulin, low HDL cholesterol, and hypertriglyceridemia. Among the 934 eligible nondiabetic participants, 15.2% exhibited microalbuminuria. The prevalence of one, two, and three or more traits was 27.0, 16.6, and 7.4%, respectively. After controlling for age, sex, smoking, body mass index, education, and family histories of diabetes and kidney disease, the odds ratio (OR) for microalbuminuria was 1.8 (95% confidence interval [CI], 1.1 to 2.8) for one IRS trait, 1.8 (95% CI, 1.0 to 3.2) for two traits, and 2.3 (95% CI, 1.1 to 4.9) for three or more traits (versus no traits). The pattern of association appeared weaker among women compared with men. Of the individual IRS traits, only hypertension and IFG were associated with microalbuminuria. Among these nondiabetic Native Americans, the IRS was associated with a twofold increased prevalence of microalbuminuria. Health promotion efforts should focus on lowering the prevalence of hypertension, as well as glucose intolerance and obesity, in this population at high risk for renal and cardiovascular disease.

Serum Folate and Risk for Ischemic Stroke: First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study

BACKGROUND AND PURPOSE A serum folate concentration < or = 9.2 nmol/L has been associated with elevated levels of plasma homocyst(e)ine. Elevated homocyst(e)ine levels have been associated with ischemic stroke in case-control studies; however, the results from prospective studies have been equivocal. We investigated whether a folate concentration < or = 9.2 nmol/L was associated with ischemic stroke in a national cohort. METHODS We used data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (n = 2006). Cox proportional hazards analyses were used to adjust for differences in follow-up time and covariates. During the 13-year follow-up, 98 ischemic strokes occurred. RESULTS After adjusting for age, race, sex, education, diabetes, history of heart disease, systolic blood pressure, body mass index, hemoglobin level, cigarette smoking, and alcohol intake, participants with a folate concentration < or = 9.2 nmol/L were at slightly increased risk for ischemic stroke (relative risk [RR], 1.37; 95% confidence interval [CI], 0.82 to 2.29). There was a folate-race interaction (P = .11 for interaction term). Whites with a folate concentration < or = 9.2 nmol/L had a relative risk of 1.18 (95% CI, 0.67 to 2.08), whereas blacks had a relative risk of 3.60 (95% CI, 1.02 to 12.71). CONCLUSIONS These findings suggest that a folate concentration < or = 9.2 nmol/L may be a risk factor for ischemic stroke, especially in blacks. However, given the small number of stroke events, additional studies are needed to assess the role of folate in the epidemiology of ischemic stroke.

National Trends in the Initial Hospitalization for Heart Failure

OBJECTIVES: Heart failure is a major health care burden among older adults, but information on recent trends has not been available. We compare rates, sociodemographic characteristics, and discharge outcomes of the initial hospitalization for heart failure in the Medicare populations of 1986 and 1993.

The Shifting Stroke Belt Changes in the Geographic Pattern of Stroke Mortality in the United States, 1962 to 1988

BACKGROUND AND PURPOSE The factors that contribute to the Stroke Belt--a concentration of high stroke mortality rates in the southeastern United States--remain unidentified. Previous hypotheses that focused on physical properties of the area have not been confirmed. This study describes changes in the locations of areas with the highest rates of stroke mortality and the implications for new hypotheses regarding the Stroke Belt. METHODS We calculated annual, age-adjusted stroke mortality rates for black women, black men, white women, and white men for the years 1962 to 1988 using a three-piece log-linear regression model. Maps were produced with the state economic area (SEA) as the unit of analysis. The baseline Stroke Belt was defined as the area with the largest concentration of high-quintile SEAs in 1962. RESULTS The concentration of high-rate SEAs tended to shift away from the Piedmont region of the Southeast and toward the Mississippi River valley. For example, whereas among black women in 1962, 72% of SEAs in the baseline Stroke Belt were in the highest quintile, by 1988 this percentage had dropped to 48%. Similar patterns were observed for the other race/sex groups. CONCLUSIONS Temporal changes in the location of areas with the highest stroke mortality rates suggest that new hypotheses for understanding the geographic pattern of stroke mortality should consider temporal trends in a variety of medical, socioeconomic, and behavioral factors.

Geographic and socioeconomic variation in the onset of decline of coronary heart disease mortality in white women.

BACKGROUND Regional, metropolitan, and socioeconomic factors related to the onset of decline of coronary heart disease (CHD) mortality among White women are reported. Such studies are important for planning population-level interventions. METHODS Mortality data for 1962 to 1978 were used, to estimate the year of onset of decline. Ecological analyses of socioeconomic data from the US census were used to emphasize structural and organizational aspects of changes in disease, rather than as a substitute for an individual-level design. RESULTS Onset of decline of CHD mortality among White women was estimated to have occurred by 1962 in 53% of 507 state economic areas (SEAs), ranging from 79% in the Northeast to 39% in the South. Metropolitan areas experienced earlier onset of decline than did nonmetropolitan areas. Average income, education, and occupational levels were highest in early onset areas and declined across onset categories. CONCLUSIONS The results provide additional evidence for previously observed geographic and social patterns of CHD decline. Emphasis on structural economic factors determining the shape of the CHD epidemic curve does not detract from the medical importance of risk factors, but underscores the importance of community development to public health improvements. The results are consistent with the idea that the course of the CHD epidemic in the United States has been strongly influenced by socioeconomic development.

Socioenvironmental characteristics associated with the onset of decline of ischemic heart disease mortality in the United States.

The relation of community socioenvironmental characteristics to timing of the onset of decline of ischemic heart disease (IHD) mortality was investigated among the 507 State Economic Areas of the continental United States. Onset of decline was measured using data for White men aged 35-74 and classified as early (1968 or before) vs late (after 1968). Ten socioenvironmental characteristics derived from US Census Bureau data were strongly related to onset of decline. Areas with the poorest socioenvironmental conditions were two to 10 times more likely to experience late onset than those areas with the highest levels. We found that income-related characteristics could account for most of the difference in onset of decline of IHD between metropolitan and non-metropolitan places. We conclude that community socioenvironmental characteristics provide the context for changes in risk factors and medical care.

Changing association between community occupational structure and ischaemic heart disease mortality in the United States.

The changing association between community occupational structure and ischaemic heart disease mortality in white men and women of the United States from 1968 to 1982 has been investigated. Occupational structure was represented by the proportion of workers in white-collar jobs. A negative association, with lower mortality in communities with higher levels of white-collar employment, emerged over the period in both men and women. The results for men may be interpreted as suggesting a recapitulation in the US of the changing association between social class and heart disease observed in Britain. Occupational structure, however, reflects resources and opportunities in a community derived from its contribution to the national and international economy. Thus the growing inequalities in heart disease mortality presented in this ecological study relate more appropriately to communities than to individual workers.

Serum Folate and Risk for Coronary Heart Disease: Results from a Cohort of US Adults

PURPOSE To assess the role of serum folate in the risk for coronary heart disease in a national cohort of US adults. METHODS Data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (N = 1921) were used to determine whether a low serum folate concentration was associated with an increased risk for incident coronary heart disease (N = 284). The Cox proportional hazards model adjusted for age, sex, race, education, serum cholesterol, systolic blood pressure, body mass index, cigarette smoking, and alcohol consumption. RESULTS The association between folate and risk for coronary heart disease differed by age group (p = 0.03). Among persons aged 35-55 years, the relative risk for heart disease was 2.4 (95% confidence interval (CI), 1.1-5.2) for persons in the lowest quartile (< or = 9.9 nmol/L) when compared with those in the highest quartile (> or = 21.8 nmol/L). However, among persons > or = 55 years the relative risk was 0.5 (95% CI, 0.3-0.8) for comparisons of the lowest versus highest quartiles. CONCLUSIONS If the age differences in the risk for heart disease are confirmed, randomized clinical trials assessing the role of folic acid for the prevention of heart disease may need to include young adults in order to demonstrate benefits related to folate supplementation.

Community Occupational Structure, Medical and Economic Resources, and Coronary Mortality among U.S. Blacks and Whites, 1980–1988

PURPOSE To examine the association between coronary heart disease (CHD) mortality, economic and medical resources, and county occupational structure. METHODS U.S. counties were classified into five occupational structure categories based on the percentage of workers in white-collar occupations. Directly age-adjusted CHD mortality rates (from vital statistics and Census data) and economic and medical care data (from Census and Area Resource File data) were calculated for each occupational structure category. Participants were black and white, men and women, aged 35-64 years, in the U.S. during 1980-88. CHD mortality rates and economic and medical care data were compared across occupational structure categories. RESULTS Among blacks, CDH rates were highest in counties with intermediate levels of occupational structure; rates among whites were inversely associated with occupational structure. Per capita levels of income and numbers of medical-care providers were positively associated with occupational structure. CONCLUSION Strategies to improve the resources of disadvantaged communities and the access of black workers to local occupational opportunities may be important for CHD prevention in high risk populations.

Antihypertensive treatment and US trends in stroke mortality, 1962 to 1980

OBJECTIVES This study examines the association between increases in antihypertensive pharmacotherapy and declines in stroke mortality among 96 US groups stratified by race, sex, age, metropolitan status, and region from 1962 to 1980. METHODS Data on the prevalence of controlled hypertension and socioeconomic profiles were obtained from three successive national health surveys. Stroke mortality rates were calculated using data from the National Center for Health Statistics and the Bureau of the Census. The association between controlled hypertension trends and stroke mortality declines was assessed with weighted regression. RESULTS Prior to 1972, there was no association between trends in controlled hypertension and stroke mortality declines (beta = 0.04, P = .69). After 1972, groups with larger increases in controlled hypertension experienced slower rates of decline in stroke mortality (beta = 0.16, P = .003). Faster rates of decline were modestly but consistently related to improvements in socioeconomic indicators only for the post-1972 period. CONCLUSIONS These results do not support the hypothesis that increased antihypertensive pharmacotherapy has been the primary determinant of recent declines in stroke mortality. Additional studies should address the association between declining stroke mortality and trends in socioeconomic resources, dietary patterns, and cigarette smoking.