FACTOR-VIII, ABO BLOOD-GROUP AND THE INCIDENCE OF ISCHEMIC-HEART-DISEASE

Relations of factor VIII activity, FVIIIC, and von Willebrand factor a ntigen (vWFAg), with ischaemic heart disease (IHD) were examined in 13 93 men aged between 40 and 64 years at entry to the Northwick Park Hea rt Study (NPHS) who experienced 178 first major episodes of IHD during an average follow-up period of 16.1 years. After allowing for the lar ge factor VIII differences between the main ABO blood groups, FVIIIC w as probably associated with IHD incidence, possibly more strongly with fatal than non-fatal episodes. Thus, an increase of 1 standard deviat ion in FVIIIC raised the risk of fatal IHD by about 28%. vWFAg was als o significantly associated with fatal events. The observed relation of FVIIIC with IHD incidence probably underestimates the true strength o f the association because of the considerable within-person and labora tory variability in factor VIII measurements. FVIIIC and vWFAg were st rongly correlated (r = 0.57) and in statistical terms there may be lit tle to choose between them in long-term studies of IHD. Taking account of evidence that haemophiliacs seem to experience less IHD than expec ted, high factor VIII levels may contribute to the incidence of IHD by increasing thrombogenic potential. The incidence of IHD was significa ntly higher in those of blood group AB than in those of groups O, A or B, particularly for fatal events. There was no evidence that the FVII IC and vWFAg associations with IHD are determined by ABO group. The fa ctor VIII and ABO blood group effects therefore appeared to be indepen dent. Group AB may be a genetic marker of characteristics influencing other indices of IHD risk such as short stature, NPHS men (though not women) of group AB being about 2 cm shorter than those of other groups .