Haemophilia protects against ischaemic heart disease: a study of risk factors.

We previously reported that mortality due to ischaemic heart disease was lower in haemophilia patients than in the general male population. To support the hypothesis that this could be attributed to a protective effect of the clotting defect in haemophilia and not to differences in cardiovascular risk factors, we performed a second study. We examined 95 haemophilia patients for the presence of major risk factors for ischaemic heart disease and compared their risk factor profile with the data of epidemiologic surveys of the general Dutch population. Haemophilia patients had on average higher blood pressures than the comparison population, were more often hypertensive and used antihypertensive drugs twice as often. The mean serum cholesterol level of the patients was markedly lower than in the comparison population (4.8 versus 5.6 mmol/l, 95% confidence interval of the difference: 0.5-1.1 mmol/l). The risk factors were weighted into one theoretical risk ratio for ischaemic heart disease by application of logistic regression coefficients. The theoretical risk ratio based on the risk factor profile was 0.78. This risk ratio can only explain a moderate reduction in the incidence of ischaemic heart disease, much smaller than the mortality ratio of 0.20 we reported previously. Therefore these data support the hypothesis of a direct protective effect of haemophilia on the development of ischaemic heart disease.