Daniel L. McGee

Diabetes and cardiovascular risk factors: the Framingham study

The impact of cardiovascular disease was compared in non-diabetics and diabetics in the Framingham cohort. In the first 20 years of the study about 6% of the women and 8% of the men were diagnosed as diabetics. The incidence of cardiovascular disease among diabetic men was twice that among nondiabetic men. Among diabetic women the incidence of cardiovascular disease was three times that among nondiabetic women. Judging from a comparison of standardized coefficients for the regression of incidence of cardiovascular disease on specified risk factors, there is no indication that the relationship of risk factors to the subsequent development of cardiovascular disease is different for diabetics and non-diabetics. This study suggests that the role of diabetes as a cardiovascular risk factor does not derive from an altered ability to contend with known risk factors

Diabetes and Glucose Tolerance as Risk Factors for Cardiovascular Disease: The Framingham Study

This report examines prospectively, in the Framingham cohort, the relation of diabetes and impaired glucose tolerance to each of the cardiovascular sequelae, taking into account age, sex, and associated cardiovascular risk factors. The incidence of cardiovascular disease, as well as the levels of cardiovascular risk factors, were found to be higher in diabetic than in nondiabetic men and women. The relative impact of diabetes on coronary heart disease, peripheral vascular disease, or stroke incidence was the same in men and women, but for cardiovascular mortality and cardiac failure the impact is greater for women. Present evidence suggests that alleviation of associated cardiovascular risk factors is the most promising course in reducing cardiovascular sequelae in diabetic patients.

A general cardiovascular risk profile: The Framingham study

Persons at high risk of cardiovascular disease can be effectively identified from a measurement of their serum cholesterol and blood pressure, a smoking history, an electrocardiogram and a determination of glucose intolerance. One general function for identifying persons at high risk of cardiovascular disease is also effective in identifying persons at risk for each of the specific diseases, coronary heart disease, atherothrombotic brain infarction, hypertensive heart disease and intermittent claudication, even though the variables used have a different impact on each particular disease. The 10 percent of persons identified with use of this function as at highest risk accounted for about one fifth of the 8 year incidence of coronary heart disease and about one third of the 8 year incidence of atherothrombotic brain infarction, hypertensive heart disease and intermittent claudication. Hence the function provides an economic and efficient method of identifying persons at high cardiovascular risk who need preventive treatment and persons at low risk who need not be alarmed about one moderately elevated risk characteristic.

Update on Some Epidemiologic Features of Intermittent Claudication: The Framingham Study

During 26 years of surveillance of the Framingham Study Cohort of 5,209 subjects, 176 men and 119 women developed occlusive peripheral arterial disease manifested as intermittent claudication (IC). The incidence increased sharply with age until the age of 75, with about a twofold male predominance at all ages. An incidence of IC comparable to that of angina pectoris was obtained ten years later in life than for angina pectoris. Cigarette smoking, impaired glucose tolerance, and hypertension were powerful predisposing factors. Impaired glucose tolerance was a greater risk in women than in men, and glycosuria carried a greater risk than other indicators of impaired glucose tolerance. Cigarette smoking had about the same impact in men and women, approximately doubling the risk, and the impact was discernible into advanced age. Hypertension increased risk 2.5‐ to fourfold, respectively, in men and women. A low vital capacity was associated with a substantial excess risk. Electrocardiographic evidence of left ventricular hypertrophy predicted IC in both sexes. Serum cholesterol, relative weight, and hematocrit were weak risk factors. A risk profile made up of the major cardiovascular risk factors was better for predicting IC than for predicting coronary heart disease. Mortality was increased two‐ to fourfold in men and women, respectively, mainly because of coexistent cardiovascular disease. J Am Geriatr Soc 33:13, 1985

The prevalence of hypertension in seven populations of west African origin.

OBJECTIVES This study was undertaken to describe the distribution of blood pressures, hypertension prevalence, and associated risk factors among seven populations of West African origin. METHODS The rates of hypertension in West Africa (Nigeria and Cameroon), the Caribbean (Jamaica, St. Lucia, Barbados), and the United States (metropolitan Chicago, Illinois) were compared on the basis of a highly standardized collaborative protocol. After researchers were given central training in survey methods, population-based samples of 800 to 2500 adults over the age of 25 were examined in seven sites, yielding a total sample of 10014. RESULTS A consistent gradient of hypertension prevalence was observed, rising from 16% in West Africa to 26% in the Caribbean and 33% in the United States. Mean blood pressures were similar among persons aged 25 to 34, while the increase in hypertension prevalence with age was twice as steep in the United States as in Africa. Environmental factors, most notably obesity and the intake of sodium and potassium, varied consistently with disease prevalence across regions. CONCLUSION The findings demonstrate the determining role of social conditions in the evolution of hypertension risk in these populations.

Socioeconomic status and health in blacks and whites : The problem of residual confounding and the resiliency of race

A large number of epidemiologic studies have focused on racial/ethnic differences, particularly between blacks and whites. Because health endpoints and racial categorizations are associated with socioeconomic status, investigators generally adjust for socioeconomic indicators. The intention is usually to control for confounding, thereby making groups comparable and excluding socioeconomic status as an alternative explanation to hypotheses of innate physiologic differences. A threat to the validity of these analyses is therefore the presence of residual confounding. We identify four potential sources of residual confounding in this analytical design: categorization of socioeconomic status variables, measurement error in socioeconomic indicators, use of aggregated socioeconomic status measures, and incommensurate socioeconomic indicators. Using simulations and examples from the literature, we demonstrate that the effect of residual confounding is to bias interpretation of data toward the conclusion of independent racial/ethnic group effects. Investigators often refer to possible “genetic” differences on the basis of models that control for socioeconomic status. We propose that such conclusions on the basis of this analytical strategy are generally unwarranted. Racial/ethnic differences in disease are a pressing public health concern, but the current approach does not often provide a basis for inference about putative biological factors in the etiology of this disparity.

Perspectives on systolic hypertension. The Framingham study.

Diastolic hypertension has been widely and justifiably accepted as a cause of cardiovascular mortality. However, it has also been accepted that the cardiovascular sequelae of hypertension derive chiefly from the diastolic component. Because systolic and diastolic pressure are usually highly correlated it is not easy to dissociate the effects of each. Statistical analysis suggests that systolic pressure is actually the more potent contributor to cardiovascular sequelae. Even isolated systolic pressure elevation is associated with an excess cardiovascular mortality. At low diastolic pressures (i.e., < 95 mm Hg), risk rises with the level of systolic pressure. Also, isolated systolic hypertension is most ominous in the elderly, in whom it is highly prevalent.Isolated systolic hypertension was related to the occurrence of “direct” complications as well as to atherosclerotic sequelae. It was also associated with excess mortality, taking into account rigid vessels as judged from pulse-wave recordings. Trials to determine whether the treatment of isolated systolic hypertension is efficacious for avoiding its demonstrated excess cardiovascular morbidity and mortality are urgently needed.

Epidemiologic features of isolated syncope: the Framingham Study.

To obtain epidemiologic information regarding syncope, 2336 men and 2873 women aged 30 to 62 years at entry to the study were evaluated for syncope. During 26 years of surveillance, evidence of cardiac or neurologic morbidity and mortality was also recorded. At least one syncopal episode was reported by 71 (3.0%) of the men and 101 (3.5%) of the women during the course of the study. Criteria for isolated syncope (i.e., transient loss of consciousness in the absence of prior or concurrent neurologic, coronary, or other cardiovascular disease stigmata) were met by 56 (79%) of the 71 men and by 89 (88%) of the 101 women with syncope. During 26 years of follow-up isolated syncope was not associated with any excess of stroke (including transient ischemic attack) or myocardial infarction. Similarly, isolated syncope was not associated with any excess of all-cause or cardiovascular mortality (including sudden death).

Duration of atrial fibrillation and imminence of stroke: the Framingham study.

The role of Atrial Fibrillation (AF) as a precursor of stroke was examined in the Framingham cohort based on 30 years of follow-up during which time 501 strokes occurred. There were 59 persons who sustained stroke in association with AF excluding those with rheumatic heart disease. AF increased the risk of stroke five-fold and the excess risk was found to be independent of the frequently associated cardiac failure and coronary heart disease. The contribution of AF to stroke risk was also at least as powerful as that of the other cardiovascular precursors. Stroke associated with AF was not only independent and substantial but also imminent. There was a distinct clustering of stroke events at the time of onset of the AF. Thirty day case-fatality rates were no different in those with strokes accompanied by AF than not at 17% versus 19% respectively. Recurrences in those with AF were only slightly more frequent, 25% versus 20%, a difference that was not statistically significant. Stroke recurrence in the first 6 months following initial stroke was more than twice as common (47% versus 20%) in the AF group.

DEATH AND CORONARY ATTACKS IN MEN AFTER GIVING UP CIGARETTE SMOKING: A Report from the Framingham Study

Abstract The Framingham study has followed a cohort of men and women, aged 29-62 when first seen, for 18 years. When two thousand, three hundred and thirty-six men were characterised by smoking status at entry, death-rates and coronary heart-disease (C.H.D.) attack-rates were found to be low for non-smokers, men smoking only cigars or pipes, and men smoking half a packet of cigarettes (i.e., 10) a day or less. Death and C.H.D. rates among men smoking more than 10 cigarettes a day at entry were distinctly higher. Furthermore, men who were cigarette smokers at entry who subsequently stopped had C.H.D. attack-rates which were half that experienced by those who continued to smoke. This difference was not explained by changes in coronary risk factors. Overall mortality was also lower in men who had given up smoking than in men who continued to smoke.