To our knowledge, this is the first observational investigation of sex difference in ABO blood group distribution among Chinese adults by propensity-matched analysis. There are several key findings: first, prevalence of A blood group was different between these with and without CAD in overall adults. Second, in our study, positive relationship between blood group A and increased risk of CAD was obtained among women, but not among men. Third, we observed that blood group A was significantly correlated with CAD independent from lipid profiles.
Prior studies have demonstrated that blood group A is more closely aligned with a higher risk of CAD compared with non-A blood groups. Furthermore, second coronary angiography indicates that in-stent restenosis is significantly more prevalent in individuals with blood group A than those with other blood groups . In the meanwhile, several studies reveal that ABO blood groups are not associated with CAD in general population [18, 19]. The results of these studies have been inconsistent or conflicting in different countries or races. Although an increased CAD risk has been demonstrated in Chinese Han patients with non-O type , the exact role of ABO type for predicting CAD events in Chinese individuals has not been addressed. Thus, it is now clinically important to understand ABO group to identify or exclude CAD risk among participants. For all the study subjects, this study revealed that patients with A type were not more to be in CAD group, and there was statistical no significance in both sexes. As we all known that cardiovascular risk factors often co-occur and may act synergistically to impact one’s overall risk of cardiovascular events. Thus, one-to-one nearest-neighbor matching was performed to balance the cardiovascular risk factors in our study. After propensity score matching analysis, distribution of A blood group were siginificantly higher in the patients with CAD ( 37.9% versus 27.7%, P = 0.006).
Recently, a case-control study was introduced for the difference, and it has demonstrated that AB blood group has a higher odd ratio for the development of CAD and can be considered as a risk factor for the development of CAD in females with DM . We believed that the association between ABO types and CAD risk might have sex-based difference in subjects. Therefore, participants were subsequently evaluated for sex-based difference in the association between ABO types and CAD. As shown in Table 1, in the women subgroup, CAD presented more frequently with blood group A, but not non-CAD ( 60.2% versus 44.1%, P = 0.014). Nervertheless, the statistically significant difference was not observed in the men subgroup (37.5% versus 30.3%, P = 0.157). After adjustment for conventional risk factors, logistic regression analysis suggested that women with blood group A had a significantly increased risk of developing CAD than those with non-A blood groups. Among Chinese women, blood group A was associated with a approximate 2.2-fold greater odds of CAD. Overall, the finding had coincided with other reports from the general population. And it was key to find sex-based difference in influence of A blood group on increased risk of coronary artery disease. Further investigations are required to validate these findings.
There are extensive evidences suggesting that ABO blood group information is not only expressed in red blood cells, but also in platelets and vascular endothelial cells. Thus, the mechanism underlying the association between ABO blood groups and CAD may be complex, and remains to be determined. Several pathways such as dyslipidemia, coagulopathy, inflammatory response (such as IL10, IL-6, and C-reactive protein), platelet aggregation and PCSK9 probably may contribute to the effect of ABO types on CAD[13, 14, 21–25]. Mediation analysis indicates that around 10.5% of the effect of A blood group on CAD is mediated by TC levels . Moreover, LDL-C level is thought to be a mediator of the effect of non-O type on coronary artery disease and myocardial infarction . Overall, it is still unclear whether there is any interaction between ABO types and lipid profiles in regard to development of CAD. Our results showed that patients with CAD had significantly higher levels of TG, LDL-C and Apo B, but statistically lower levels of HDL-C and Apo A-1. However, the concentrations of TC, TG, HDL-C, LDL-C, Apo A-1 and Apo B were similar for women with A group, versus non-A group. In our study, the results of correlation analysis showed that, among Chinese women, A type was correlated positively with CAD. And there were no relationships between A type and age, smoking, DM, HBP, SBP, HR, TG, HDL-C, LDL-C, Apo A-1 and Apo B. After adjustment for age, CAD remained significantly correlated with A type (r = 0.171, P = 0.003). The results highlighted our findings that the effect of ABO blood groups on development of CAD in Chinese women was not mediated by lipid levels.
Several limitations to this study need to be considered. First, the optical coherence tomography (OCT) examination indicates that the plaques of blood group O are exhibited more stably compared with non-O blood groups. And the non-O groups have more serious coronary artery stenosis than O blood group . For lack of OCT, assessment for plaques in CAD patients particularly those with blood group A was absent in our study. Second, it was a single-center, retrospective, observational study, baseline data such as body mass index, physical activity and socioeconomic status was incomplete. Our results could be biased for small sample size. Furthermore, nutraceuticals can influence lipids metabolism and act on lipids metabolism. However, the information was absent.Therefore, multicenter, large-scale and prospective studies will be required to clarify the association of ABO blood group distribution with CAD and cardiovascular risk factors in Chinese patients.