Key result
Clofibrate reduced the incidence of heart attacks compared with controls, with the reduction being most noticeable in hypertensive heavy smokers (P<0.01).
Why the study?
Does clofibrate reduce the incidence of heart attacks in men, and how do blood pressure and smoking modify this effect?
RCT (n=15,000)
Yes
Does clofibrate reduce the incidence of heart attacks in men, and how do blood pressure and smoking modify this effect?
Clofibrate reduced the incidence of heart attacks most noticeably in hypertensive heavy smokers, possibly by reducing fibrinogen levels, though it is not recommended for widespread use.
Supports targeted use in hypertensive smokers; extends RCT evidence on effect modification by BP and smoking.
Green K G (c/o Heady, Department of Clinical Epidemiology and General Practice, Royal Free Hospital School of Medicine, London, NW3 2PF, UK), Heady J A and Oliver M F. Blood pressure, cigarette smoking and heart attack in the WHO co-operative trial of clofibrate. International Journal of Epidemiology 1989, 18: 355–360. In the WHO sponsored trial of clofibrate and its follow-up, about 15000 men were observed for a mean period of 13.2 years. As expected, incidence of heart attacks (HA) was directly related to serum cholesterol, blood pressure (BP) and cigarette smoking. The previously reported lower incidence of HA in men receiving clofibrate compared with controls was most noticeable in hypertensive heavy smokers (P<0.01). BP was slightly lower in smokers than non-smokers (P<0.01). The difference in BP was greater in the trial visit before HA. Smokers also had higher plasma fibrinogen levels (P<0.05). The combination of reduced diastolic BP, and therefore myocardial perfusion pressure, with an increased thrombogenic tendency, might explain the high incidence of HA in smokers. Clofibrate apparently reduced fibrinogen levels, which might account for its specially good effect in preventing HA in smokers. However, the ill effects of smoking are still evident at a lower level in the men taking clofibrate and the drug is no substitute for giving up the habit. Clofibrate is not recommended for widespread use, except in subjects with marked lipid and/or blood fibrinogen abnormalities after dietary measures have been tried.
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Green et al. (1989) conducted an RCT in Heart attack risk (n=15,000). Clofibrate vs. Controls was evaluated on Incidence of heart attacks (p=<0.01). Clofibrate reduced the incidence of heart attacks compared with controls, with the reduction being most noticeable in hypertensive heavy smokers (P<0.01).
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