Education, smoking and non-cardiovascular mortality: findings in three Chicago epidemiological studies.

The interrelationships among education, smoking, and non-cardiovascular (non-CVD) mortality were examined in middle-aged white males from the Chicago Peoples Gas Company Study (PG), the Chicago Western Electric Company Study (WE), and the Chicago Heart Association Detection Project in Industry (CHA). In each study, college graduates had the lowest prevalence of current smokers and the highest prevalence of former smokers. The associations between education and smoking were strongest in CHA, a study with baseline measurements 10-14 years after those of PG and WE and 3-8 years after the US Surgeon General's report on smoking and health in 1964. In PG and WE, the relative risks of non-CVD death for those who did not attend college compared to those who did were 1.50 and 1.38 (95% limits, 1.04 to 2.18 and 0.95 to 2.02). In CHA, the relative risk for those who did not graduate from college compared to those who did was 1.55 (1.17, 2.05). Differences in baseline cigarette smoking could account for only 23-29% of these increased risks. Because the associations between education and non-CVD mortality may have been confounded by changes in smoking status over the course of follow-up in these studies, non-CVD deaths were subdivided into those from causes related to smoking and causes not related to smoking. For smoking-related causes, the relative risk of death for those who did not attend/graduate from college was 1.95 (0.96, 3.95) in WE, 2.13 (1.18, 3.87) in PG, and 2.34 (1.47, 3.84) in CHA, while the relative risks for causes not related to smoking were 1.17, 1.12 and 1.16, respectively. These findings suggest that education is related inversely to non-CVD mortality primarily through smoking and smoking-related causes of death. With smoking becoming increasingly a habit of the less well-educated, these findings underscore the need for smoking prevention and cessation programmes targeted at the lower end of the socioeconomic scale.

Relative weight and blood pressure in four Chicago epidemiologic studies.

Because systolic blood pressure rises more sharply with age than diastolic blood pressure, leading to an increasing prevalence with advancing age of elevated systolic blood pressure without elevated diastolic pressure, i.e. so-called pure systolic hypertension, the question arises as to whether or not pure systolic hypertension has its own etiology and pathogenesis. Since pure systolic hypertension is characterized by a widened pulse pressure, the present report examined the association between relative weight and pulse pressure, both cross-sectionally and prospectively, in addition, to the association between relative weight and the level of blood pressure, in four Chicago epidemiologic studies. The positive association between relative weight and the level of blood pressure in these studies, in both cross-sectional and prospective analyses, reaffirms the finding in previous studies of a positive association between weight and blood pressure and the prevalence and incidence of hypertension. However, the results of these studies did not generally support the hypothesis that relative weight is related to pulse pressure, and thus possibly to pure systolic hypertension.

Methodological problems in characterizing an individual's plasma glucose level.

Two methodological problems in characterizing an individual's plasma glucose level are examined in this study. First, how large is the intra-individual variation of an individual's 1-hr post-load glucose level and for this estimated intra-individual variation what are the probabilities of misclassifying individuals based on a one-time measurement only of glucose level? Second, do different tests-i.e. fasting, 1-hr, 2 hr post-load, GTT-yield consistent ranking for the same individual? The first of these was explored with data on subsamples from the Chicago Peoples Gas Company (PG) study and the Chicago Heart Association Detection Project in Industry (CHA) study; the second, with data from the Chicago Coronary Prevention Evaluation Program (CPEP). For both the PG and CHA studies, the estimated ratios of the intra- to inter-individual variances were generally higher for post-load plasma glucose than blood pressure, heart rate, weight and serum uric acid. The conditional probabilities of misclassifying individuals into quintiles or deciles based on one measurement of 1-hr post-load glucose were also estimated from these data. These estimated probabilities indicated that the possible attenuation due to intra-individual variation cannot abolish a strong association; however, it may create some problem if the relationship is not very strong. Furthermore, both rank correlation and quintile classification analyses show that fasting, 1-hr and 2-hr plasma glucose level characterize individuals differently. Thus it is possible that the inconsistent results of previous studies, all using a one-time measure of plasma glucose, are partially due to the large intra-individual variation of this variable, and the use of methods that are not highly consistent in their classification of individuals.

Pulse pressure-I. Level and associated factors in four Chicago epidemiologic studies.

Because systolic blood pressure rises more sharply than diastolic blood pressure for those middle aged and beyond, leading to an increasing prevalence with advancing age of elevated systolic blood pressure without elevated diastolic pressure, i.e. so-called pure systolic hypertension, the question arises as to whether or not factors that have been shown to be related to blood pressure and hypertension are related to pure systolic hypertension or to 'classical' hypertension, i.e. hypertension defined solely by the level of the diastolic pressure. This question was examined in four Chicago epidemiologic studies by examining the associations between several variables and pulse pressure, with pulse pressure redefined so that the association between a variable and pulse pressure indicated whether the variable was more strongly related to systolic or diastolic blood pressure. In these four studies, glucose, heart rate and cigarette use tended to show a stronger association with systolic pressure, suggesting a possible association with pure systolic hypertension, while hematocrit, serum cholesterol, and uric acid tended to be more strongly associated with diastolic pressure, or equally associated with systolic and diastolic pressure, suggesting an association with 'classical' hypertension. Relative weight tended to be more strongly associated with systolic pressure under the age of 35 and more strongly associated with diastolic pressure after age 45.

Pulse pressure-II. Factors associated with follow-up values in three Chicago epidemiologic studies.

This report, the second in a series on pulse pressure and pure systolic hypertension, examined in prospective analyses the associations between both the initial values of five variables and the changes in these variables and pulse pressure, utilizing data from three Chicago epidemiologic studies, in order to determine whether variables known to be related to blood pressure and hypertension are related to pure systolic hypertension or 'classical' hypertension. In these analyses follow-up pulse pressure, which was measured from 2-5 years after the initial measurement of the other variables, was redefined so that the association between the initial value or change and pulse pressure indicated whether the initial value or change was more strongly related to follow-up systolic or diastolic blood pressure. In these three studies, only the initial value for cigarette use had a consistent positive association with follow-up pulse pressure. Change in heart rate was generally positively related to follow-up pulse pressure, while the initial value was not. For relative weight and serum cholesterol, both the change and the initial tended to be negatively related. For glucose, the association was not consistent for either the initial value or the change. The results from these prospective analyses thus suggest that cigarette use is related to pure systolic hypertension, rather than 'classical' hypertension.

Pulse pressure-III. Prognostic significance in four Chicago epidemiologic studies.

This report, the third in a series on pulse pressure and pure systolic hypertension, examines the associations between blood pressure and the cardiovascular diseases and coronary heart disease, both cross-sectionally and prospectively, utilizing data from four Chicago epidemiologic studies, in an effort to determine whether or not a widened pulse pressure, or pure systolic hypertension, is an independent risk factor. In these analyses, blood pressure is divided into two components, one related to level and the other to pulse pressure, with pulse pressure redefined so that the association between pulse pressure and the prevalence of ECG abnormalities or mortality, indicates whether the endpoint is more strongly related to systolic or diastolic blood pressure. In these studies, blood pressure level is significantly related to both ECG abnormalities and mortality. In the cross-sectional analyses, pulse pressure is generally positively related to the prevalence of ECG abnormalities, indicating a stronger association for systolic blood pressure, and thus a possible association with pure systolic hypertension. However, in the prospective analyses, pulse pressure is generally not related to mortality, indicating an equal association with mortality for systolic and diastolic blood pressure in these studies. Thus, although the cross-sectional analyses generally support the hypothesis that a widened pulse pressure, or pure systolic hypertension, is an independent risk factor for the cardiovascular diseases and coronary heart disease, the prospective analyses do not.

Heart rate: a risk factor for cancer?

The relationship between heart rate and cancer mortality was examined in 3 Chicago epidemiologic studies: 1233 white men originally age 40-59 followed 18 years from the Chicago Peoples Gas Company study; 1899 white men originally age 40-55 followed 17 years from the Chicago Western Electric Company study; 5784 white men originally age 45-64 followed 5 years from the Chicago Heart Association Detection Project in Industry. There was a significant association between heart rate and cancer mortality in both univariate and multivariate analyses in men from the Gas Company study and in men from the Chicago Heart Association study, but there was no association between heart rate and cancer mortality in men from the Western Electric study. The relationship persisted in the Gas Company study but not in the Chicago Heart Association study after eliminating deaths within the first 2 years of follow-up. With cancer deaths broken down by the site, mortality from lung and colon cancer in the Gas Company study and mortality from lung cancer in the Chicago Heart Association study were significantly associated with baseline heart rate on univariate analysis and on bivariate analysis controlling for age. Only colon cancer in the Gas Company, however, remained associated with heart rate when other variables were controlled. Thus, in 2 of the 3 studies examined, heart rate appeared to be an independent risk factor for cancer mortality in men.

Alcohol, cardiovascular risk factors and mortality: the Chicago experience.

The association between alcohol consumption and cardiovascular risk factors, the association between alcohol consumption and the incidence of high blood pressure, and the association between alcohol consumption and mortality, both all-cause and cause-specific, were examined in the white males from the Chicago Peoples Gas Company study and the Chicago Western Electric Company study. In both studies, there was a significant cross-sectional association between heavy alcohol use--defined as problem drinking in the Gas Company and as consumption of six or more drinks per day in the Western Electric Company--and the level of blood pressure and high blood pressure. In addition, in 1340 normotensive men ages 27-64 years from the Gas Company and in 871 normotensive men ages 40-55 years from the Western Electric Company, a significant prospective relationship was shown, for the first time, between heavy drinking and risk of developing high blood pressure. In the Gas Company, among 1233 men ages 40-59 years, 38 problem drinkers had significantly higher 15-year mortality from all causes, the cardiovascular diseases and coronary heart disease than the rest of the men. In the Western Electric study, 78 men who consumed six or more drinks per day had significantly higher 17-year mortality from all causes, the cardiovascular diseases and coronary heart disease, cancer and all other causes than the rest of all men.

Heart rate as a prognostic factor for coronary heart disease and mortality: findings in three Chicago epidemiologic studies.

The associations between heart rate and death from the cardiovascular diseases (CVD), coronary heart disease (CHD) and sudden death from CHD, along with death from all causes and non-cardiovascular causes, are examined for three groups of middle-aged white males: 1233 men aged 40-59 years followed for 15 years from the Chicago Peoples Gas Company study; 1899 men aged 40-55 years followed for 17 years from the Chicago Western Electric Company study; and 5784 men aged 45-64 years followed an average of five years from the Chicago Heart Association Detection Project in Industry. In univariate analyses, mortality from both cardiovascular and non-cardiovascular causes generally increases with increasing heart rate. In bivariate analyses, using the Cox regression model to control for age, heart rate is significantly related to mortality from all causes in each study, with the associations again due to both cardiovascular and non-cardiovascular causes. In multivariate Cox regression, controlling for age, blood pressure, serum cholesterol, cigarettes smoked per day and relative weight, heart rate is a significant risk factor for sudden CHD death and non-CVD death in two of the three studies, with the association with sudden death being U-shaped in one of the studies. Although heart rate may be an independent risk factor for sudden CHD death, the associations with other CVD death and non-sudden CHD death, in general, appear to be secondary to associations between heart rate and other cardiovascular risk factors.

Uric acid: a risk factor for coronary heart disease?

The association between serum uric acid and the prevalence of ECG abnormalities was analyzed for 24.997 employed men and women, white and black, age 18--64 years, from the Chicago Heart Association (CHA) Detection Project in Industry. In addition, the relationships between uric acid and 5-year mortality from all causes, from cardiovascular diseases (CVD), and from coronary heart disease (CHD) were analyzed for 7804 white men and women age 45--64 years from this study and 967 white men age 44--63 years from the Chicago People's Gas Company Study. For men, the association between uric acid and the prevalence of ECG abnormalities and with mortality appear to be secondary to associations between uric acid and other risk factors. For women, however, the associations could not be explained by other risk factors.

A hypertension control program based on the workplace. Report on the Chicago Center.

In several large Chicago companies and institutions, workplace screening of 7,151 persons yielded 833 suspect hypertensives. Of these, 91% attended a follow-up verification visit, where for 513 persons high diastolic pressure was confirmed. One-half of these persons were referred to their physicians for treatment and one-half were randomly assigned to be treated directly by HDFP, in a step-wise pharmacologic regimen to normalize diastolic pressure. Of the 257 persons assigned to program treatment, 94% accepted such treatment, and over 90% of these still living in the community were active participants at one year. Average diastolic pressure of these active participants was 83.1 mm Hg at one year, compared to 102.6 at first screen and 98.8 at the second confirmatory screening. A strenuous effort has been made to reduce or eliminate obstacles to treatment, including lack of understanding of the need for long-term therapy, cost barriers and barriers of inconvenience of treatment. The medical team conducting the program combined physicians with nonphysician therapist-health counselors, plus "outreach" staff, to maximize program adherence. Preliminary experiences in the Chicago Center of the Hypertension Detection and Follow-Up Program (HDFP) give encouraging evidence that the workplace is a useful base for successful hypertension control efforts.

Alcohol consumption, cardiovascular risk factors, and mortality in two Chicago epidemiologic studies.

Multivariate analysis of the association at baseline between problem drinking and cardiovascular risk factors among 1,233 white male employees of the Chicago Peoples Gas Company age 40-59 showed the 38 problem drinkers with significantly higher blood pressures and cigarette consumption and significantly lower relative weights than the others. Similar analysis among 1,899 white male employees of the Hawthorne Works of the Western Electric Company in Chicago age 40-55 showed the 117 men consuming 5 or more drinks per day with significantly higher blood pressures and cigarette use than the others. No significant differences were recorded between heavy drinkers and the others in serum cholesterol level. The gas company problem drinkers had significantly higher 15-year mortality rates from all causes, cardiovascular diseases, coronary heart disease, and sudden death. These differences could not be entirely explained by their blood pressure, smoking, and relative weight status. The Western Electric heavy drinkers had increased 10-year mortality rates both for all causes and noncardiovascular causes.

High blood-pressure: a risk factor for cancer mortality?

Univariate and multivariate analyses have been made of the relationship of systolic and diastolic blood-pressure measured at study entry to subsequent 14-year mortality among 1233 White males originally age 40-59 in 1958 from the Chicago Peoples Gas Company prospective study. With age, serum-cholesterol, and cigarettes per day controlled, both elevated systolic and electaed diastolic blood-pressure in 1958 were found to be strongly related to subsequent mortality from cancer in the men of this study. The possibility that this finding was due either to an association between antihypertensive medication in general, and cancer, or to an association was found that could explain the excess cancer mortality among those with elevated blood-pressure in 1958, either with medication in general, or with reserpine and rauwolfia in particular. These findings thus pose the question, is high blood-pressure associated with an increased risk of death due to cancer?