Biomedical subjects

D S Freedman

Publications and source records attributed to D S Freedman.

At least 19 recordsLinked to original sources

PubMed1997

Secular increases in relative weight and adiposity among children over two decades: the Bogalusa Heart Study.

OBJECTIVE: To examine trends in relative weight and obesity among 5- to 24-year-olds between 1973 and 1994. DESIGN: A panel design consisting of seven cross-sectional surveys of schoolchildren and three surveys of post-high-school subjects. Anthropometric measurements included height, weight, and subscapular and triceps skinfolds. STUDY POPULATION: All schoolchildren residing in Ward 4 of Washington Parish, Louisiana, a biracial community, were considered eligible; participation rates were >80%. Young adults were eligible if they had participated previously as schoolchildren. A total of 26,371 examinations were performed on 11,564 persons. RESULTS: During the study period, substantial increases in mean levels of weight (0.2 kg/y) and skinfold thickness (0.15 mm/y) were observed; these changes were independent of height, age, and other covariates. The prevalence of overweight, defined by the 85th percentile of weight-for-height in 1973 to 1974, increased approximately twofold by 1994. Although secular increases were seen both among boys and girls and among blacks and whites, the largest increases were seen among 19- to 24-year-olds. Furthermore, the yearly increases in relative weight and obesity during the latter part of the study period (1983 through 1994) were approximately 50% greater than those between 1973 and 1982. CONCLUSIONS: The increasing prevalence of obesity in early life indicates a need for primary prevention. Additional study is needed to determine whether these trends are continuing to accelerate and to examine possible explanations, such as diet and physical activity, for these changes.

Adolescent↗

PubMed1996

Baldness and ischemic heart disease in a national sample of men.

A weak positive association between male pattern baldness and ischemic heart disease has been suggested previously. The authors examined this issue by using data from the Epidemiologic Follow-up Study of the First National Health and Nutrition Examination Survey. As part of the baseline medical examination between 1971 and 1975, the presence and degree of male alopecia (none, minimal, moderate, and severe) were recorded for a subset of participants. Among 3,932 men aged 25-76 years who had complete data, 378 deaths and 939 incident events from ischemic heart disease occurred during an average follow-up period of 14 years. Among 2,019 men who were younger than age 55 years at baseline (61 deaths and 239 incident events of ischemic heart disease), severe baldness was positively associated with ischemic heart disease mortality (rate ratio = 2.51, 95 percent confidence interval 1.01-6.24) and somewhat less associated with ischemic heart disease incidence (rate ratio = 1.72, 95 percent confidence interval 0.96-3.08). No dose-response relation with degree of baldness was seen. Although these findings are tempered by the absence of information concerning the type of baldness (frontal or vertex), they provide support for earlier studies that indicate male pattern baldness that occurs before age 55 years may be by some mechanism related to ischemic heart disease.

Adult↗

PubMed1996

Education, health behaviors, and the black-white difference in waist-to-hip ratio.

Few epidemiologic studies have investigated the impact of body mass index, low educational attainment, cigarette smoking, and physical activity on the considerable black-white difference in waist-to-hip ratio. These relationships were assessed with multivariable linear regression among 3,094 adults (24% black) who were examined in 1987 in South Carolina. The unadjusted mean waist-to-hip ratio was lower for black men than for white men (-0.03 units) and higher for black women than for white women (+0.03 units). After adjustment for age, body mass index, education, smoking, and physical activity, the black-white difference in mean waist-to-hip ratio was -0.02 units (p < 0.001) among men and +0.01 units (p < 0.01) among women. Although differing distributions of age, body mass index, and educational attainment accounted for a 59% reduction in the black-white difference among women, these factors did not explain the difference among men. Thus, these results suggest that other environmental or biologic factors may also play an important role in the marked variation in body fat distribution between the two ethnic groups. The results also support the importance of the prevention of cigarette smoking and overweight in potentially preventing abdominal obesity in both black adults and white adults.

Adult↗

PubMed1996

Correlates of leukocyte counts in men.

Because of previously reported associations between a high leukocyte count and risk of ischemic heart disease (IHD), we examined the relation of leukocyte counts to various characteristics among 3591 white and 506 black 31- to 45-year-old men. The mean leukocyte count was approximately 1000 cells/microL higher among whites than among blacks, and approximately 1900 cells/microL higher among current smokers than among nonsmokers. The leukocyte count was also higher among men who had recently stopped smoking and among men who reported their general health as poor or fair. Independent of these relations, the leukocyte count was associated positively with the platelet count (r = 0.29), triglyceride level (r = 0.21), heart rate (r = 0.15), and use of corticosteroids and beta-blockers; and inversely with alcohol consumption and prothrombin time (r = -0.10). The examined characteristics could together account for 37% of the variability in leukocyte counts. These relatively strong associations indicate that it may be difficult to disentangle the relation of the leukocyte count to IHD from that of other risk factors.

Adult↗

PubMed1996

Cigarette smoking and leukocyte subpopulations in men.

Because of previously reported associations among the total leukocyte count, cigarette smoking, and risk of cardiovascular disease, we examined the relation of cigarette smoking to various leukocyte subpopulations among 3467 men aged 31 to 45 years. The median total leukocyte count was 36% higher (7840 vs. 5760 cells/mL) among current cigarette smokers than among men who had never smoked, and both stratification and regression analyses were used to examine independent associations with leukocyte subpopulations. At equivalent counts of other subpopulations, CD4+ lymphocytes and neutrophils were the cell types most strongly associated with cigarette smoking; each standard deviation change in counts of these subpopulations increased the odds of current (vs. never) smoking by approximately threefold. Furthermore, whereas 15% of the 238 men with relatively low (< 25 percentile) counts of both neutrophils and CD4+ lymphocytes were cigarette smokers, 96% of the 249 men with relatively high counts of both subpopulations were current smokers. Counts of T lymphocytes also tended to be higher among the 32 men with self-reported ischemic heart disease than among other men. These results, along with previous reports of immunologically active T lymphocytes in atherosclerotic plaques, suggest that this subpopulation may be of particular interest in studies examining the relation of leukocytes to cardiovascular disease.

Adult↗

PubMed1995

Relation of body fat distribution to ischemic heart disease. The National Health and Nutrition Examination Survey I (NHANES I) Epidemiologic Follow-up Study.

Although an excess of adipose tissue in the abdominal and truncal regions is associated with various metabolic alterations, relatively few cohort studies have examined its importance in the development of ischemic heart disease, and little information is available from black populations. The authors examined the relation of central obesity, as characterized by a thick subscapular skinfold relative to the triceps skinfold, to the incidence of ischemic heart disease among 9,822 persons in the Epidemiologic Follow-up Study of the National Health and Nutrition Examination Survey I; baseline data were collected in 1971-1975 and follow-up was through 1987. We found that, independently of relative weight, cigarette smoking, and other covariates, the hazard rate ratios for ischemic heart disease incidence contrasting the upper and lower quintiles of central obesity were 1.75 (95% confidence interval 1.3-2.3) among women and 1.65 (95% confidence interval 1.3-2.2) among men. Although central obesity was related similarly to disease among white and black men, the association among women differed between whites (rate ratio = 1.94) and blacks (rate ratio = 0.73); p = 0.002 for race x the central obesity product term. Additional research is needed to clarify the relation of various anthropometric measurements to ischemic heart disease, particularly among blacks, but the assessment of fat distribution may help identify high-risk persons for whom weight loss might be most beneficial.

Adipose Tissue↗

PubMed1995

Relation of serum uric acid to mortality and ischemic heart disease. The NHANES I Epidemiologic Follow-up Study.

Although hyperuricemia is frequently found among persons with ischemic heart disease, its importance as a risk factor remains uncertain. The authors examined this relation among 5,421 persons in the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study; baseline data were collected in 1971-1975 and follow-up was through 1987. No associations were seen among men, but, among women, the serum uric acid level was predictive of mortality from all causes and from ischemic heart disease. These associations persisted even after excluding the first 10 years of follow-up and were independent of use of antihypertensive agents and diuretics, diastolic blood pressure, overweight, and other characteristics. A dose-response relation was evident for mortality from ischemic heart disease: each 1-mg/dl change in uric acid (about two thirds of the standard deviation) among women increased the rate by 1.48 (95% confidence interval 1.3-1.7). Furthermore, as compared with women who had a uric acid level < 4 mg/dl, those with a level > or = 7 mg/dl had a 4.8-fold (95% confidence interval 1.9-12) higher rate of ischemic heart disease mortality. In contrast, the uric acid level showed a weaker relation with disease incidence among women, with a rate ratio of 1.14 for each 1-mg/dl change. Although the biologic mechanism is unclear, further investigation into the possible role of uric acid in the development of ischemic heart disease is needed.

Adult↗

PubMed1995

Plasma lipid levels and psychologic characteristics in men.

Results of several studies suggest that either a reduction in the serum level of total cholesterol level or a persistently low cholesterol level may be associated with an increase in violent deaths. Although there are several possible explanations for these observations, it has been suggested that the cholesterol level could influence various behaviors. We therefore examined the cross-sectional relation of several psychologic characteristics, assessed by the Diagnostic Interview Schedule and the Minnesota Multiphasic Personality Inventory, to levels of total cholesterol, high-density lipoprotein cholesterol, and triglycerides among 3,490 men aged 31-45 years who were examined in 1985-1986. (All men had served in the US Army between 1965 and 1971). Compared with that of other men, the mean total cholesterol level was 5 mg/dl higher among 697 men diagnosed with generalized anxiety disorder (possibly because of increased catecholamine levels) and 7 mg/dl lower among 325 men with antisocial personality disorder (p < 0.01 for each association). These differences could not be attributed to education, relative weight, cigarette smoking, use of various medications, or other potential confounders. In contrast, cholesterol levels were not significantly associated with major depression or hostility; levels of high-density lipoprotein cholesterol and triglycerides were not related to any diagnosis. If the serum level of total cholesterol is found to be predictive of antisocial personality disorder in longitudinal analyses, this association may have implications for cholesterol-lowering recommendations.

Adult↗

PubMed1995

The importance of body fat distribution in early life.

It is possible that many of the conflicting findings concerning obesity and cardiovascular disease may be the result of the heterogeneous nature of obesity, adn that only certain subgroups of the obese are at increased risk. Over the last several decades, much attention has focused on the distribution of body fat as an important characteristic in the metabolic and clinical alterations associated with obesity. Several studies have shown that a relative excess of adipose tissue in the upper body, abdominal region, or at various truncal sites is associated with an increased risk of disease; furthermore, these associations are independent of the general level of obesity. This article presents a brief historical overview of the idea of body fat distribution, the measurement techniques that have been used, and the complications associated with an adverse distribution of body fat distribution; particular emphasis is given to studies that have examined fat patterning in early life. Although most investigators recognize that body fat distribution is important in the development of cardiovascular disease, several questions remain.

Adipose Tissue↗

PubMed1995

Subclinical health effects in a population exposed to excess vitamin D in milk.

To evaluate subclinical health effects of excess vitamin D, a cross-sectional study was conducted of persons consuming milk from a dairy that had overfortified milk for at least 4 years. Milk consumption, sunlight exposure, medical symptoms, serum 25-hydroxyvitamin D (25[OH]D), serum and urinary calcium, and indicators of renal function were measured. Increased milk consumption was associated with increased serum 25(OH)D and urinary calcium. However, the prevalences of elevated serum 25(OH)D and calcium were no greater than expected, and data indicated normal renal function. It was concluded that most persons exposed to excess vitamin D exhibited no measurable adverse subclinical effects.

25-Hydroxyvitamin D 2↗

PubMed1994

The relation of documented coronary artery disease to levels of total cholesterol and high-density lipoprotein cholesterol.

Recommendations for identifying persons at high risk for coronary heart disease are based primarily on levels of total and low-density lipoprotein cholesterol. We examined whether, given knowledge of these levels, information on the high-density lipoprotein cholesterol level would improve the prediction of arteriographically documented coronary artery disease among 591 men. We found that even at levels of total and low-density lipoprotein cholesterol considered desirable, high-density lipoprotein cholesterol was inversely related to disease severity. For example, among the 112 men with a total cholesterol level <180 mg per dl, the mean occlusion score (representing the overall severity of disease) was 107 among men with a high-density lipoprotein cholesterol level < or = 30 mg per dl vs a mean score of 52 among men with levels > or = 45 mg per dl. Furthermore, men with low levels of both low-density lipoprotein cholesterol (< 110 mg per dl) and high-density lipoprotein cholesterol (< or = 30 mg per dl) had as much occlusive disease as did men with high levels of both lipoprotein fractions. Given information on the ratio of high-density lipoprotein cholesterol to total cholesterol, the actual levels of the lipoprotein fractions did not improve disease prediction. Our results emphasize the importance of considering high-density lipoprotein cholesterol when assessing coronary heart disease risk.

Adult↗

PubMed1993

Do obese children become obese adults? A review of the literature.

BACKGROUND: Obese children may be at increased risk of becoming obese adults. To examine the relationship between obesity in childhood and obesity in adulthood, we reviewed the epidemiologic literature published between 1970 and July 1992. Comparison between studies was complicated by differences in study design, definitions of obesity, and analytic methods used. Although the correlations between anthropometric measures of obesity in childhood and those in adulthood varied considerably among studies, the associations were consistently positive. RESULTS: About a third (26 to 41%) of obese preschool children were obese as adults, and about half (42 to 63%) of obese school-age children were obese as adults. For all studies and across all ages, the risk of adult obesity was at least twice as high for obese children as for nonobese children. The risk of adult obesity was greater for children who were at higher levels of obesity and for children who were obese at older ages. CONCLUSION: The wide range of estimates in this literature are, in part, due to differences in study designs, definitions of obesity, ages at which participants were measured, intervals between measurements, and population and cultural differences.

Adolescent↗

PubMed1993

The relation of atherosclerotic lesions to antemortem and postmortem lipid levels: the Bogalusa Heart Study.

Although postmortem lipid levels have been used as surrogates for levels during life, it is uncertain whether atherosclerotic lesions are related similarly to antemortem and postmortem lipid values. In a sample of 23 children and young adults who had been examined for cardiovascular disease risk factors and subsequently died from violent causes, we examined the relation of (a) postmortem lipid levels to values obtained 1 to 14 years earlier, and (b) atherosclerotic lesions to antemortem and postmortem lipid levels. Postmortem levels of triglycerides and very-low-density lipoprotein cholesterol (VLDLC) were higher than levels during life, but postmortem levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDLC) and high-density lipoprotein cholesterol (HDLC) were related to antemortem levels (rs > 0.40). After excluding eight persons who likely received large volumes of intravenous fluids before death, the within-person variability between antemortem and postmortem levels of LDLC and HDLC was similar to the antemortem variability. Furthermore, the relation of atherosclerotic lesions to antemortem and postmortem lipid levels differed only slightly for TC, LDLC and HDLC. In contrast, lesions in the coronary arteries showed the strongest association with antemortem VLDLC levels, but were not associated with postmortem VLDLC levels. Despite the very small number of subjects, our results suggest that if intravenous fluids are not administered before death, postmortem levels of TC, LDLC and HDLC are fairly representative of levels during life. Postmortem levels of VLDLC or triglycerides, however, should not be used as surrogates for antemortem levels.

Adolescent↗

PubMed1992

The relation of prothrombin times to coronary heart disease risk factors among men aged 31-45 years.

Although levels of coagulation factor VII and fibrinogen are predictive of cardiovascular disease, relatively little data describe hemostatic characteristics in healthy populations. The cross-sectional associations between the prothrombin time, a measure of the activity of the extrinsic and common pathways of coagulation, and traits associated with the risk of cardiovascular disease were therefore examined among 3,604 white and 514 black, male, US Army veterans aged 31-45 years. The prothrombin time measurements, performed in 1985 and 1986, were precise, with an intraclass correlation of 0.98 (202 pairs). Overall, the mean prothrombin time was 12.4 seconds (standard deviation, 0.4 seconds), and 11 percent of the men had a value of less than 12 seconds. Many of the observed associations with the prothrombin time paralleled those that have been reported with clotting factor VII and fibrinogen. The mean prothrombin time was 0.15 seconds shorter among whites than among blacks and was 0.2 seconds shorter among current cigarette smokers than among men who had never smoked. Inverse associations were also seen with relative weight and with levels of total cholesterol and triglycerides (r = -0.09 to -0.16). All associations were statistically significant at the 0.01 level, and the examined characteristics could jointly account for about 12 percent of the variability in prothrombin times. Additional data on characteristics related to coagulation may help elucidate the natural history of cardiovascular disease and aid in the design of clinical trials.

Adult↗

PubMed1992

Serum cholesterol levels in a multiracial sample of 7,439 preschool children from Arizona.

BACKGROUND: The distribution and correlates of serum levels of total cholesterol were studied in cross-sectional analyses of 7,439 1 to 4 year olds examined through the Arizona Department of Health Services. RESULTS: Mean cholesterol levels increased with age, and levels among 2 year olds approached those seen in adolescents. Racial and ethnic differences in cholesterol levels were observed: mean (age-adjusted) levels were 147 mg/dl among American Indians (n = 622), 153 mg/dl among Hispanics (n = 3165), 154 mg/dl among non-Hispanic whites (n = 3448), and 163 mg/dl among blacks (n = 204). Cholesterol levels were not associated either with obesity, as assessed by relative weight or the Quetelet index, or with breast-feeding during infancy. Very overweight (greater than or equal to 20 kg/m2) 3 and 4 year olds, however, tended to have higher mean levels of cholesterol than did other children. The proportion of children with borderline (170 to 199 mg/dl) or high (greater than or equal to 200 mg/dl) levels of cholesterol varied by race/ethnicity: borderline (high) levels were seen among 14% (3%) of American Indians and 29% (11%) of blacks. The proportions of white and Hispanic children having cholesterol levels between 170 and 199 mg/dl or greater than or equal to 200 mg/dl were midway between those seen among American Indians and blacks. CONCLUSION: Additional information on the interrelationships of lipids and lipoproteins may aid in the identification of children who will be at increased risk for cardiovascular disease in adulthood.

Age Factors↗

PubMed1992

Cholesterol and coronary artery disease: age as an effect modifier.

An elevation of serum cholesterol has been one of the more frequently cited risk factors for coronary heart disease, found in both case-control and cohort studies. As a result, this country has undertaken massive screening of adults older than 20 years of age in an attempt to identify those persons with cholesterol levels greater than 200 mg/dl, and follow up with an active approach for intervention. The suggested cutpoints for borderline (200-240 mg/dl), and definite (> or = 240 mg/dl) hypercholesterolemia have been applied to all age groups despite suggestions of a diminution of risk conferred by cholesterol in the elderly. This study of 2544 white men undergoing coronary angiography shows that for all men, aged 25-84 years, plasma cholesterol levels were associated with an increase in coronary artery occlusion (rs = 0.15, p < 0.01). However, when stratified by age, this association held only for the younger men, the association diminishing to near zero in the oldest age group. The negative interaction between cholesterol levels and age in predicting coronary artery disease proved highly significant (p < 0.001) in multivariable linear regression analysis, suggesting that cholesterol levels are much less predictive of coronary artery disease in the elderly as compared to the young. These results point to the need for a more finely tuned set of criteria for the evaluation of hypercholesterolemia, one that takes into account the age of the screenee.

Adult↗

PubMed1992

Interpretation of linear regression models that include transformations or interaction terms.

In linear regression analyses, we must often transform the dependent variable to meet the statistical assumptions of normality, variance stability, or linearity. Transformations, however, can complicate the interpretation of results because they change the scale on which the dependent variable is measured. In this setting, the inclusion of product terms or the transformation of some independent (or predictor) variables may further complicate interpretation. In this article, we present some interpretations of linear models that include transformations or product terms. We illustrate these interpretations using regression analyses designed to study determinants of serum testosterone levels. These examples show how one can present results using simple measures, such as medians, and interpret regression parameters.

Epidemiologic Methods↗

PubMed1992

Education, race, and high-density lipoprotein cholesterol among US adults.

OBJECTIVES: Although educational achievement is positively related to levels of high-density lipoprotein cholesterol (HDL-C) among White adults, there is an inverse association among Blacks. We assessed whether this interaction could be attributed to differences in the relation of education to correlates of HDL-C. METHODS: Cross-sectional analyses were based on data from 8391 White and 995 Black adults who participated in the Second National Health and Nutrition Examination Survey. RESULTS: Associations between education and HDL-C levels varied from negative (Black men), to nearly nonexistent (White men and Black women), to positive (White women). Mean HDL-C levels were higher among Blacks than among Whites, but differences varied according to educational achievement. Among adults with less than 9 years of education, mean levels were 6 to 10 mg/dL higher among Blacks, but the radical difference was less than 1 mg/dL among adults with at least 16 years of education. About 20% to 40% of these differences could be accounted for by obesity, alcohol consumption, and other characteristics. CONCLUSIONS: Because of the implications for coronary heart disease risk, consideration should be given to behavioral characteristics associated with the interaction between race and educational achievement.

Adult↗