Ischaemic heart disease: association with haematocrit intheBritish Regional HeartStudy

Objectives - To assesstherelationship betweenhaematocrit andriskofmajor ischaemic heartdisease events. Design -Prospective studyofacohortof men followed upfor95years. Setting- General practices in24townsin England,Wales,and Scotland(British Regional HeartStudy). Subjects -Altogether 7735men aged4059yearsatscreening, whowereselected atrandomfromonegeneral practice in eachof24towns,werestudied. Mainoutcomemeasures -Fatalandnonfatal ischaemic heartdisease events. Results -Riskofmajorischaemic heart disease events wassignificantly increased athaematocrit levels of >46-0%.Men with raisedhaematocrit(>46-0%) showeda 30% increase inrelative risk (RR)ofmajorischaemic heartdisease events(RR=132;95%confidence intervals(CI)1P10,1P57, p<0-01)compared withthosewithvalues below46-0%, even afteradjustment forage,social class, smoking, bodymassindex, physical activity, bloodcholesterol, lungfunction (FEVy), andpre-existing evidence ofischaemicheartdisease. Further adjustment forsystolic bloodpressure reducedthe riskslightly (RR=1-27; 95%CI1-06,1-51, p=002)butitremainedsignificant. The relationship wasseeninmen withand withoutpre-existing evidence ofischaemicheartdisease. Thestudysuggests thatanincreased haematocrit level plays apartinthedevelopment ofmajorischaemicheartdisease events. (J7 Epidemiol Community Health 1994;48:112-118)