Steven J. Bowlin

Validity of cardiovascular disease risk factors assessed by telephone survey: The behavioral risk factor survey

The Behavioral Risk Factor Surveillance System (BRFSS) collects telephone interview data on behaviors for the leading causes of premature death and disability. Its validity has never been adequately studied. The authors replicated BRFSS methodology to validate self-reported cardiovascular disease (CVD) risk factors. Nine-hundred and eleven subjects from three upstate New York counties were interviewed between 1/89 and 5/90. Interviewees were offered physical examinations and laboratory testing for CVD risk factors; 282 men and 344 women participated. The authors studied validity by comparing objectively measured to self-reported CVD risk factors. Sensitivities for self-reported hypertension, hypercholesterolemia, obesity, smoking, and diabetes were: 43, 44, 74, 82 and 75%, respectively. Only smoking sensitivity differed by gender: men, 77%; women, 86%. Specificity was > 85% for all risk factors, except hypercholesterolemia in men (75%). Prevalence was underreported for hypertension, hypercholesterolemia, obesity, and smoking by 43, 50, 25 and 17%, respectively. Results suggest telephone survey research includes physiologic measurements for blood pressure, cholesterol, height, weight, and smoking to validate self-reported CVD risk factors. When this is impossible, results such as these can be used, in similar samples, to correct risk factor prevalence rates from telephone surveys for misclassifications.

Reliability and changes in validity of self-reported cardiovascular disease risk factors using dual response: The behavioral risk factor survey

The authors previously studied the validity of self-reported cardiovascular disease (CVD) risk factors assessed by telephone surveys, and found the validity low, especially for self-reported hypertension and hypercholesterolemia. One way to improve validity is to combine repeated measurements (dual response) into a single measure. The authors explored this and the reliability of self-reported CVD data collected by the Behavioral Risk Factor Survey in three New York counties from January 1989 to May 1990. Nine hundred and eleven subjects were interviewed by telephone to collect CVD risk factor and health behavior information. Interviewees were offered physical examination and laboratory testing to verify self-reported CVD risk factors; 628 participated. Subjects were also reinterviewed to assess the test-retest reliability of the survey, and to study how validity of self-reported CVD data changes by dual response. Reliability coefficients for CVD risk factors, preventive health practices, and knowledge of risk factor levels ranged from 0.42 to 0.99. Minimal improvement in sensitivity of self-reported risk factors was found using dual response, and it did not improve specificity. Also, for prevalence of risk factors, dual response minimally improved self-reported rates compared to objective estimates. Combining self-reported measurements causes minimal changes in the validity of these variables. Physiological assessment for hypertension and hypercholesterolemia, or correction for misclassification, is needed for valid individual measurement and for community prevalence estimates from telephone surveys. Self-reported cigarette smoking, obesity, and diabetes mellitus have better validity, but physiological assessment or correction for misclassification may supplement these self-reported risk factors.

Longitudinal changes in dehydroepiandrosterone concentrations in men and women

Dehydroepiandrosterone, an adrenal steroid, has many purported roles in the body and has been used as an oral supplement in the treatment of various illnesses. Because little is known about normal changes over time in dehydroepiandrosterone concentrations, we studied the 5-year change in plasma dehydroepiandrosterone concentrations in 614 free-living adults. Two hundred seventy-three males and 341 females had dehydroepiandrosterone and dehydroepiandrosterone sulfate concentrations measured in 1989 and 1994. Demographic data were also obtained. Dehydroepiandrosterone concentrations differed significantly by sex and 5-year age group. The average decline in dehydroepiandrosterone was 5.6%/year, and the rate of decline was directly related to age but not to sex, measures of adiposity, or serum glucose. Dehydroepiandrosterone sulfate concentrations differed significantly by sex and age group. The average decline in the sulfated hormone was 2.0%/year and was not related to age, sex, measures of adiposity, or serum glucose. Knowledge of the natural course of age-related changes in dehydroepiandrosterone and dehydroepiandrosterone sulfate concentrations is essential to our understanding of the relationship of dehydroepiandrosterone to chronic diseases.

INTERMITTENT CLAUDICATION IN 8343 MEN AND 21-YEAR SPECIFIC MORTALITY FOLLOW-UP

PURPOSE As Western populations live longer, peripheral vascular disease will become a greater individual and public health problem. Therefore, the long-term natural history of intermittent claudication (IC) needs further delineation. The study objective was to describe the 21-year mortality and relative risk for cause-specific mortality for subjects with incident IC. METHODS The subjects were 8343 Israeli male governmental employees aged 40-65 years who were free of coronary heart disease and symptomatic peripheral vascular disease in 1963. These men were followed for 21 years to measure differences in mortality between those who did and did not develop incident IC. Incident IC was diagnosed in 1965 and 1968 by the London School of Hygiene IC Questionnaire. All other cardiovascular disease risk factors were measured by standardized and validated procedures. Cause-specific mortality through 1986 was determined through death certificates from the Israeli Mortality Register. RESULTS A total of 360 men with IC and 7983 symptom-free men were followed for survival from 1965 to 1986; 159 men with IC (44%) and 2330 symptom-free men (29%) died. For total mortality, the Kaplan-Meier 21-year survival probabilities were 56% for IC and 71% for symptom-free men (P < 0.0001 for the entire 21-year survival difference between the two groups). For coronary heart disease (CHD), stroke, and other causes of death, the survival probabilities for men with IC and symptom-free men were, respectively: 85% vs. 90%, 89% vs. 97%, and 79% vs. 83% (P = 0.0004; P < 0.0001; and P = 0.007, respectively, for the entire 21-year survival difference between the two groups). Coxs proportional hazards model was used to control confounding from incident myocardial infarction and angina through 1968, as well as for demographic, physiologic, psychosocial, and other cardiovascular disease risk factors. The 21-year adjusted all-cause mortality relative risk for IC was 1.50 (95% confidence interval (CI), 1.28-1.77). For stroke deaths the relative risk was 2.76 (95% CI, 1.89-4.02). For stroke mortality, IC was the third strongest predictor of death after elevated systolic blood pressure and increasing age. Incident IC had a relative risk of CHD deaths of 1.31, but it was not statistically significant (P = 0.08; 95% CI, 0.97-1.77). IC was not statistically significantly related to other causes of death (P = 0.10) after adjustment for covariates. CONCLUSIONS IC is strongly predictive of long-term cerebrovascular disease mortality among men. Incident IC is a stronger indicator of cerebrovascular than of CHD death.

Atrial fibrillation as a risk factor for stroke: a retrospective cohort study of hospitalized Medicare beneficiaries.

OBJECTIVES This study examined the relationship between atrial fibrillation and (1) stroke and (2) all-cause mortality. METHODS All eligible Medicare patients older than 65 years of age hospitalized in 1985 were followed up for 4 years. Kaplan-Meier and Cox proportional hazards models were used for assessment of risk of stroke and mortality. RESULTS A total of 4,282,607 eligible Medicare patients were hospitalized in 1985. The mean age was 76.1 (+/- 7.7) years; 58.7% were female; 7.2% were Black; and 8.4% had a diagnosis of atrial fibrillation. During the follow-up period, 66,063 patients (32.6/1000 person-years) developed nonembolic stroke and 7285 (3.6/1000 person-years) developed embolic stroke. After adjustment for age, race, sex, and comorbid conditions, atrial fibrillation remained a significant risk factor for both nonembolic stroke (relative risk [RR] = 1.56) and embolic stroke (RR = 5.80) and for mortality (RR = 1.31). Approximately 4.5% of nonembolic and 28.7% of embolic strokes among hospitalized Medicare patients aged 65 years and older were attributable to atrial fibrillation. CONCLUSIONS This study demonstrates that atrial fibrillation is associated with an appreciable increase in the risk of stroke (both embolic and nonembolic) and in the risk of mortality from all causes.

An ecological study of the effectiveness of mammography in reducing breast cancer mortality.

OBJECTIVES The purpose of this study was to determine the relation of screening mammography to breast cancer incidence and case fatality. METHODS In a sample of White female Medicare beneficiaries hospitalized in 1990-1991, age-adjusted breast cancer incidence and 2-year case fatality rates were estimated and compared with the frequency of mammographic screening from a population-based survey. RESULTS The average rates for incidence, case fatality, and mammography within 5 years in 29 states were 414/100,000, 18.8%, and 59.2%, respectively. There was a positive state-level correlation between mammography rates and incidence and an inverse correlation between mammography and case fatality. CONCLUSIONS High screening mammography rates in some states are associated with reduced breast cancer case fatality rates, presumably as a result of diagnosis of earlier stage cancers.