Meta-analysis of the association of HLA-DRB1 with rheumatoid arthritis in Chinese populations

BACKGROUND Individual studies have reported different results regarding the association of HLA alleles with RA in Chinese populations. This study was performed to systematically summarize results on the association of HLA-DRB1 with rheumatoid arthritis (RA) in China. METHODS We examined the case-control studies concerned about the relationship between HLA-DRB1 and RA and differences of clinical and laboratory parameters between the HLA-DR4 (DR4)+ and DR4- in RA patients in Chinese populations. Odds ratios (ORs) and weighted mean difference (WMD) with corresponding 95% confidence intervals (CI) was used to describe the relationship. RESULTS 22 studies with 1690 cases and 1793 controls were included. Chinese populations with RA had significantly higher frequencies of HLA-DRB1*04, *0401, *0404, *0405 and *0410 than controls (ORDRB1*04 =4.19, 95% CI =3.44-5.11, p<0.00001; ORDRB1*0401 =2.53, 95% CI =1.54-4.16, p=0.0003; ORDRB1*0404 =2.28, 95% CI =1.28-4.06, p=0.005; ORDRB1*0405=3.71, 95% CI =2.52-5.45, p<0.00001; ORDRB1*0410 =2.99, 95% CI =1.25-7.14, p=0.01 respectively). As to laboratory parameters, Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Rheumatoid factor (RF), Anti-cyclic citrullinated peptide antibodies (Anti-CCP ) in patients with DR4+ were higher than patients with DR4- (WMD=0.26, 95% CI =0.15-0.37, p<0.00001; WMD = 0.26, 95% CI =0.12-0.41, p=0.0005; WMD = 0.44, 95% CI =0.23-0.65, p<0.00001; WMD = 0.58, 95% CI =0.24-0.91, p=0.0007 respectively). As to clinical features, there was no difference in duration of morning stiffness, number of swollen joints, number of joint tenderness, X-ray phases and joint function between the DR4+ and DR4- in RA patients. CONCLUSIONS It was found that HLA-DRB1*04, *0401, *0404, *0405 and *0410 are risk factors for RA in Chinese populations. ESR, CRP, RF, Anti-CCP are different between the DR4+ and DR4- in RA patients in Chinese populations, while there's no difference for indexes of clinical features.