HLA-DRB1 or DQB1 allele carrier frequency in the RA cases with specific DQB1 or DRB1 alleles (two locus analysis).

ILD(+)RA: ILD positive RA, ILD(−)RA: ILD negative RA, OR: odds ratio, 95%CI: confidence interval, Pc: corrected P value, NS: not significant. Allele frequencies are shown in parenthesis (%). Association was tested by Fisher’s exact test using 2×2 contingency tables.ILD(+)RA：ILD阳性类风湿关节炎（ILD positive RA），ILD(−)RA：ILD阴性类风湿关节炎（ILD negative RA）；OR：比值比（odds ratio）；95%CI：95%置信区间（confidence interval）；Pc：校正P值（corrected P value）；NS：无统计学意义（not significant）。等位基因频率以括号内百分比形式标注。关联分析采用基于2×2列联表的费希尔精确检验进行。