HLA-DRB1 and systemic lupus erythematosus: All studies included in this meta-analysis need conform to the following inclusion criteria: (1) a case-control study to appraise the association between HLA-DRB1 polymorphisms and SLE susceptibility; (2) with sufficient available data to estimate an odds ratio (OR) with 95% confidence interval (95% CI); (3) for multiple studies conducted in the same population or subpopulation, the latest or most complete publications shall be selected; and (4) all cases met the diagnostic criteria for SLE revised by the American College of Rheumatology (ACR) in 1982 or 1997.