Prevalence of three major risk factors in random sample of men and women, and in patients with ischaemic heart disease.

A random sample of 283 men and 250 women between the ages of 30 and 69 years has been investigated for the three coronary risk factors-smoking, hyperlipoproteinaemia, and hypertension, and 146 men and 87 women with ischaemic heart disease have undergone a similar investigation. Smoking and hyperlipoproteinaemia are significantly more common in both men and women in ischaemic heart disease groups but hypertension is not substantially different. The prevalence of any one of these three risk factors is the same in the random sample and ischaemic heart disease groups, but the prevalence of two or more factors is significantly greater in the ischaemic heart disease groups. The absence of all three risk factors is commoner in the random sample. The prevalence of smoking is far greater in men with ischaemic heart disease than in the equivalent female patients, whereas the prevalence of hyperlipoproteinaemia is significantly greater in women. Young men in the random sample have a significantly greater prevalence of all three factors than young women, but in the whole age range cigarette smoking is the only factor significantly greater in men than in women. In the whole random sample 24 per cent ofmen and 9 per cent ofwomen have two or more risk factors. In men the combination of smoking with either of the other two factors is significantly more common in the ischaemic heart disease group, but the combination of hypertension plus hyperlipoproteinaemia is not. In women, however, hypertension plus hyperlipoproteinaemia is the commonest combination and is significantly more common in the ischaemic heart disease group.In the random sample the combination of cigarette smoking with one or both ofthe other two factors is 7 times more common and smoking plus hypertension 25 times more common in men than in women. Types IIa and IV hyperlipoproteinaemia are more common in both men and women with ischaemic heart disease than in their random samples, but Type IIb is significantly increased only in women with ischaemic heart disease. It is suggested that reporting the prevalence of a single risk factor without knowing what other factors are present can be misleading. Our data suggest that a substantial partof thepreponderance of ischaemic heart disease in men relates to their greater prevalence of major risk factors in the younger age range, and particularly to the greater prevalence of moderately heavy cigarette smoking in combination with one or more of the other factors.