Interstitial lung disease in non-sicca onset primary Sjögren's syndrome: a large-scale case-control study.

Aim: This study investigated the common initial clinical presentations of primary Sjögren's syndrome (pSS) with interstitial lung disease (ILD) and explored differences between sicca and non-sicca onset pSS-ILD patients.

Method: A total of 1341 SS patients hospitalized between 2003 and 2012 were retrospectively reviewed. Of them, 102 were analyzed and recruited to examine the differences between non-sicca and sicca onset.

Results: Fifty-one percent of pSS-ILD patients presented with non-sicca onset. Although the mean diagnosis time was equal, only 4% of non-sicca onset patients were diagnosed with pSS at onset versus 34% with sicca onset (P = 0.000). Hyperglobulinemia, elevated rheumatoid factor (RF) titer, and anti-SSA and/or anti-SSB presence were less predominant in patients with non-sicca onset (immunoglobulin G, 16 [12-21] vs. 21 [15-28] g/L, P = 0.032; RF, 22 [20-171] vs. 104 [20-237] IU/mL, P = 0.048; anti-SSA and/or anti-SSB presence, 33% vs. 72%, P = 0.000). The usual interstitial pneumonia pattern was more commonly seen in non-sicca onset patients (20.0% vs. 14.3%). The high-resolution computed tomography score was higher (12 [88-15] vs. 8 [5-13], P = 0.070) and predicted total lung capacity and forced vital capacity were lower (87 ± 23% vs. 97 ± 20%, P = 0.050; 88 ± 28% vs. 100 ± 27%, P = 0.089) in non-sicca patients.

Conclusion: Non-sicca is a common initial manifestation in pSS-ILD. Anti-SSA presence, elevated RF titer and hyperglobulinemia were less predominant, and pulmonary complications were more progressive and severe in non-sicca onset patients than sicca onset patients.