M.F. Oliver

Risk of angina pectoris and plasma concentrations of vitamins A, C, and E and carotene

The relation between risk of angina pectoris and plasma concentrations of vitamins A, C, and E and carotene was examined in a population case-control study of 110 cases of angina, identified by the Chest Pain Questionnaire, and 394 controls selected from a sample of 6000 men aged 35-54. Plasma concentrations of vitamins C and E and carotene were significantly inversely related to the risk of angina. There was no significant relation with vitamin A. Smoking was a confounding factor. The inverse relation between angina and low plasma carotene disappeared and that with plasma vitamin C was substantially reduced after adjustment for smoking. Vitamin E remained independently and inversely related to the risk of angina after adjustment for age, smoking habit, blood pressure, lipids, and relative weight. The adjusted odds ratio for angina between the lowest and highest quintiles of vitamin E concentrations was 2.68 (95% confidence interval 1.07-6.70; p = 0.02). These findings suggest that some populations with a high incidence of coronary heart disease may benefit from eating diets rich in natural antioxidants, particularly vitamin E.

LINOLEIC AND EICOSAPENTAENOIC ACIDS IN ADIPOSE TISSUE AND PLATELETS AND RISK OF CORONARY HEART DISEASE

The relation between the fatty-acid composition of adipose tissue and platelet membranes and the estimated relative risk of coronary heart disease (CHD) was examined in a case-control study of new angina pectoris (AP) and first acute myocardial infarction (AMI). There were progressive inverse relations between adipose linoleic acid and platelet-membrane eicosapentaenoic acid and the estimated relative risk of AP. These relations were statistically independent of each other and traditional CHD risk factors. For AMI there was a progressive inverse relation between adipose linoleic acid and the estimated relative risk, but it was confounded by smoking habit. Smokers consume less linoleic acid than non-smokers. Although eicosapentaenoic acid in platelet membranes was lower in AMI patients than in controls, this difference was not significant. The estimated proportionate increase in risk of AP, independent of other CHD risk factors, was 1.2 (1.1-1.3) for a 1% decrease in linoleic acid or a 0.1% decrease in eicosapentaenoic acid.

ADIPOSE TISSUE AND PLATELET FATTY ACIDS AND CORONARY HEART DISEASE IN SCOTTISH MEN

The relation between coronary heart disease (CHD) and fatty acid composition of adipose tissue and platelets was examined in a random sample of 448 middle-aged Scottish men. The linoleic acid (18:2n6) content in adipose tissue of 28 men with previously unidentified CHD was significantly lower than that in the rest of the group. Platelet linoleic and other fatty acids were not significantly different in men with new CHD. Fatty acid content of adipose tissue reflects long-term dietary intake, and a 7-day weighed dietary record in a random sub-sample of 164 men confirmed that intake of linoleic acid in 10 of the 28 new CHD cases was significantly lower than in the healthy men. In a multiple logistic analysis adipose tissue linoleic acid, age, high density lipoprotein cholesterol, and weight/height index each made an independent contribution to the explanation of new CHD. When all fatty acids were included in a second regression analysis, low concentrations of dihomo-gamma-linolenic (20:3n6) acid in adipose tissue showed a more significant relation with new CHD than did linoleic acid.

NATURAL HISTORY OF UNSTABLE ANGINA

Abstract The preliminary results are reported of the first eighteen months of a study of the natural history of unstable angina. The findings are based on a prospective community survey conducted with general practitioners in Edinburgh. During the survey, 385 patients with symptoms suggestive of myocardial ischaemia were referred from the selected practices to a special clinic, and 167 were accepted as cases of unstable angina. Of these, 3 died suddenly and 23 developed acute myocardial infarction within three months: 17 of these 26 complications occurred within four weeks of the onset of symptoms. During the same period, 79 further cases of sudden death occurred in the same selected practices. The majority had no known preceding chest pain, although 40% had attended their doctors for various complaints not attributable to myocardial ischaemia during the preceding month. 110 cases of myocardial infarction also occurred in the selected practices: in 60% there was preceding unstable angina, but only a quarter of these reported this to their doctors. It is concluded from this interim assessment that 14% of patients who complain to a physician of unstable angina develop acute myocardial infarction. Sudden death is a relatively infrequent sequel. Furthermore, it is apparent that sudden death is seldom preceded by ischaemic symptoms which are reported to a physician.

CONSENSUS OR NONSENSUS CONFERENCES ON CORONARY HEART DISEASE

Oliver criticizes the use of consensus development conferences to provide health policy recommendations and cites as examples two such recent conferences, one on coronary artery bypass surgery in Great Britain, and the other on the link between blood cholesterol and heart disease in the U.S. He identifies sources of bias in the conference conclusions and suggests alternative policy-formulating approaches that provide for the involvement of a broad range of experts, in-depth review of the subject, and sufficient time. He recommends that ad hoc national or international panels be convened to examine policy issues, or that standing advisory commissions be appointed to respond to topical questions.