ABO blood group and risk of coronary heart disease in two prospective cohort studies

Abstract

Objective: Epidemiological data regarding the association between ABO blood groups and risk of coronary heart disease (CHD) have been inconsistent. We sought to investigate the associations between ABO blood group and CHD risk in prospective cohort studies.

Methods and results: Two large, prospective cohort studies (the Nurses' Health Study [NHS] including 62 073 women and the Health Professionals Follow-up Study [HPFS] including 27 428 men) were conducted with more than 20 years of follow-up (26 years in NHS and 24 years in HPFS). A meta-analysis was performed to summarize the associations from the present study and previous studies. In NHS, during 1 567 144 person-years of follow-up, 2055 participants developed CHD; in HPFS, 2015 participants developed CHD during 517 312 person-years of follow-up. ABO blood group was significantly associated with the risk of developing CHD in both women and men (log-rank test; P=0.0048 and 0.0002, respectively). In the combined analysis adjusted for cardiovascular risk factors, compared with participants with blood group O, those with blood groups A, B, or AB were more likely to develop CHD (adjusted hazard ratios [95% CI] for incident CHD were 1.06 [0.99-1.15], 1.15 [1.04-1.26], and 1.23 [1.11-1.36], respectively). Overall, 6.27% of the CHD cases were attributable to inheriting a non-O blood group. Meta-analysis indicated that non-O blood group had higher risk of CHD (relative risk =1.11; 95% CI, 1.05-1.18; P=0.001) compared with O blood group.

Conclusions: These data suggest that ABO blood group is significantly associated with CHD risk. Compared with other blood groups, those with the blood type O have moderately lower risk of developing CHD.

Figure 1. Cumulative incidence curves for CHD by ABO blood group in NHS and HPFS

Number of participants at risk is shown for selected times.

Figure 2. Forest plot showing the RR of CHD for non-O blood group for individual cohort studies and all studies combined

Bars and the diamond indicate 95% CIs. The size of the squares corresponds to the weight of the study in the meta-analysis.