Association between the ABO blood group and primary knee osteoarthritis: A case–control study

BACKGROUND: Recent studies have suggested association between the ABO blood group and inflammation, which was a crucial pathological process of primary knee osteoarthritis. The aim of this study was to investigate the association between the ABO blood group and primary knee osteoarthritis ​and the severity of primary knee osteoarthritis evaluated by the Kellgren/Lawrence score, as well as the histopathologic association in a subgroup of patients. METHODS: We performed a retrospective review of patients with primary knee osteoarthritis that served as the case group ​and a random sampling of healthy blood donors that served as the control group. The severity of knee osteoarthritis at the first outpatient visit was evaluated by the Kellgren/Lawrence scoring system. Further study was performed to investigate the expression of blood group antigens in synovial tissue of the knee in both cases and controls. RESULTS: A total of 1126 cases and 30299 controls were involved. The proportion of AB blood group was higher in the case group than in the control group (9.7% vs. 7.8%), and logistic regression revealed that the AB blood group was a risk factor of primary knee osteoarthritis (P ​= ​0.025 and 0.048 for univariate and multivariate analysis, respectively), independent of age (P ​= ​0.973) and sex (P ​= ​0.520). Patients of the blood group AB had a higher Kellgren/Lawrence score (P ​= ​0.017). The immunohistochemical study indicated association between Le(Y) antigen and primary knee osteoarthritis (P ​= ​0.029). CONCLUSIONS: This study suggested that the blood group AB was associated with primary knee osteoarthritis, as well as its radiological severity. Further study indicated that Le(Y) antigen, which was related to the blood group, was associated with primary knee osteoarthritis. TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This study revealed that blood group AB and Le(Y) antigen was associated with primary knee osteoarthritis, which shed new light on the nature of osteoarthritis, and the development of novel therapy for osteoarthritis.