ISCHEMIC-HEART-DISEASE - ASSOCIATION WITH HEMATOCRIT IN THE BRITISH-REGIONAL-HEART-STUDY

Objectives - To assess the relationship between haematocrit and risk of major ischaemic heart disease events. Design - Prospective study of a cohort of men followed up for 9.5 years. Setting- General practices in 24 towns in England, Wales, and Scotland (British Regional Heart Study). Subjects - Altogether 7735 men aged 40-59 years at screening, who were selected at random from one general practice in each of 24 towns, were studied. Main outcome measures - Fatal and nonfatal ischaemic heart disease events. Results - Risk of major ischaemic heart disease events was significantly increased at haematocrit levels of greater than or equal to 46.0%. Men with raised haematocrit (greater than or equal to 46.0%) showed a 30% increase in relative risk (RR) of major ischaemic heart disease events (RR=1.32; 95% confidence intervals (CI) 1.10,1.57, p<0.01) compared with those with values below 46.0%, even after adjustment for age, social class, smoking, body mass index, physical activity, blood cholesterol, lung function (FEV,), and pre-existing evidence of ischaemic heart disease. Further adjustment for systolic blood pressure reduced the risk slightly (RR=1.27; 95% CI 1.06,1.51, p=0.02) but it remained significant. The relationship was seen in men with and without pre-existing evidence of ischaemic heart disease. The study suggests that an increased haematocrit level plays a part in the development of major ischaemic heart disease events.