TRIM21 and interstitial lung disease: When patients were categorized into three groups, ILD‐specific PFS was significantly longer in the non‐isolated anti‐SSA seropositive and anti‐SSA seronegative groups compared with the isolated anti‐SSA seropositive group, with hazard ratios of 0.20 (95% CI: 0.06–0.72) and 0.22 (95% CI: 0.08–0.62), respectively (Figure S3).