Prevalence, risk factors, and prognosis of interstitial lung disease in a large cohort of Chinese primary Sjögren syndrome patients: A case-control study.

To determine the prevalence of pulmonary complications in primary Sjögren syndrome (pSS), and to identify the risk factors and the prognosis associated with pulmonary involvement in pSS patients.A total of 1341 hospitalized patients (853 with pSS and 488 with secondary Sjögren syndrome [sSS]) were retrospectively reviewed. Of these, 165 hospitalized patients with pSS-associated interstitial lung disease (ILD) were analyzed and recruited as a study group. Eighty-four pSS patients without organ damage were included as a control group.One hundred and sixty-five patients (19.34%) from the pSS group and 126 patients (25.82%) from the sSS group presented with lung involvement. Of the 165 pSS patients with lung complications, 151 (91.5%) were women. The mean age was 61.25 ± 9.79 years, and the median disease duration was 84 (24-156) months. Non-specific interstitial pneumonia (NSIP; 39.1%) was the predominant pattern on high-resolution computed tomography (HRCT). The total HRCT score was 9.71 ± 4.77. Impairment in diffusion capacity was the most common (74.3%) and severe complication (predicted value of TLCO was 57.5 ± 21.2%). The 5-year survival rate for all patients with pSS-ILD was 88.5%. Age, disease duration, rheumatoid factor (RF), and C-reactive protein (CRP) were significantly higher than in controls, whereas anti-SSA was less common. Age, RF, and CRP were independent predictors of ILD after adjustment for confounders.Lung involvement is a common and severe complication of Sjögren syndrome. Age and disease activity are correlated with pulmonary involvement in pSS patients.