Relatively high coronary death and event rates in Turkish women: Relation to three major risk factors in five-year follow-up of cohort

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Abstract

The study describes rates of coronary heart disease death and nonfatal coronary events over five years in a cohort of random sample population and relates them to levels of three major risk factors. It is based on a longitudinal follow-up of survey conducted initially in 1990 in all geographic regions of Turkey. Two-thirds of the original cohort aged 20 years or over - 2259 adults comprising 1146 women - was followed up by physical examination and an ECG recording at rest. New coronary events were defined to include myocardial infarction and stable angina with or without associated myocardial ischemia developed during the follow-up period. Overall annual death rate was nine per 1000 adults. Coronary deaths numbered 55 (of which 26 were women) representing 4.1 per year and were found high in women. New coronary events were registered in 37 men and 32 women (annual rates 7.2 and 5.8 per 1000, respectively). Among male participants aged initially 40 years or over, high systolic blood pressure (≥130 mmHg) at baseline significantly predicted coronary death (age-adjusted risk ratio (RR) 3.3) while high cholesterol concentrations (≥5.2 mmol l−1) predicted new coronary events alone (RR almost 2). In women systolic pressure again strongly predicted coronary death (age-adjusted RR 3.9), whereas abnormal cholesterol levels discriminated for coronary death and new coronary events (RR around 2.3 for each). High diastolic pressure (≥85 mmHg) was of predictive value for the combined outcome of coronary death and events in women (RR 1.9) but not in men. Multivariate analysis by logistic regression identified systolic blood pressure in men as significant independent predictor of coronary death, while total cholesterol concentration in both gendres and systolic blood pressure in men were independent predictors of the combined outcome of coronary death or nonfatal coronary events. It was concluded that known major risk factors act in similar magnitudes commensurate with the specific risk increments also in populations with essentially low cholesterol levels. The relatively high coronary morbidity and mortality in Turkish women approaching that in men may be accounted for by an inherent greater risk burden.

Introduction

Various studies have shown the coronary mortality and morbidity rates in industrialized populations. In particular, the MONICA Project of the World Health Organization has been monitoring coronary death rates and coronary event rates in many cities of the Western world [1]. With the exception of Japan and China, the Project involves communities having high levels of plasma cholesterol. Turkish adults were shown to have comparatively low cholesterol levels [2]and low high-density lipoprotein cholesterol levels [3], which might affect the contribution of major risk factors to coronary events or mortality. Moreover, the scarcity of prospective studies published on risk factors in women has been underlined [4].

It was therefore of interest to study in a longitudinal fashion the original cohort of the Turkish nationwide cardiac survey conducted in 1990. The survey, based on a representative sample of over 3600 Turkish adults, examined the prevalence of heart diseases as well as the risk factors for coronary heart disease. A follow-up of five years demonstrated high coronary death rates in Turkish women approaching that in Turkish men. The purpose of this paper is 1) to analyze the mortality and morbidity results of the follow-up survey of a Turkish cohort, 2) to delineate the relation of coronary deaths and events to systolic and diastolic blood pressure as well as to plasma cholesterol levels and smoking at baseline of the study.

Section snippets

Population and methods

The survey on the prevalence of cardiac disease and risk factors in adults in Turkey comprised 3687 men and women 20 years of age or over residing in 59 communities scattered over all seven geographical regions of the country. Surveyed in the summer of 1990 was a random sample of the Turkish adult population, representatively stratified for sex, age, geographical regions and for rural-urban distribution [5]. In the summer of 1994, the cohort of the Marmara region constituting one-quarter of the

A. Rates of death, coronary death and nonfatal coronary events

A total of 119 deaths (67 in men, 52 in women) were recorded during a mean follow-up of 4.73 years. Of these, 45 were classified as being due to coronary heart disease (24 in men and 21 in women) and ten deaths in each gender were of indeterminate nature, while 54 deaths were designated as not due to CHD (33 men, 21 women). These comprised 16 due to cerebrovascular accidents, 23 due to various malignancies, five due to accidents, one suicide and nine deaths from other causes.

The total period in

Discussion

The present paper is part of the only Turkish study in the field of cardiovascular epidemiology which follows a population-based cohort. Several limitations of the study exist which include the relatively small number of coronary deaths and events, the loss to follow-up of about one-third of the original cohort which might introduce a type two error, and uncertainty regarding assertion of diagnosis in a limited group of cases. The former is related in part to the comparatively young mean age of

Acknowledgements

We appreciate the dedicated work of Drs I. Keleş, K. Dönmez, G. Kahraman, B. Ökçün and E. Ince, the coworkers in the survey teams, and the assistance in biostatistical evaluation of Prof. Mustafa Şenocak, Cerrahpaşa Medical Faculty, Istanbul University. We thank the Pfizer and Sandoz pharmaceutical companies (Istanbul) for partial financial support.

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