Prognostic factors of interstitial lung disease associated with primary Sjögren's syndrome

Abstract

Objectives: Interstitial lung disease associated with primary Sjögren's syndrome (pSS-ILD) shows a variety of patterns such as nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP). The prognostic factors in pSS-ILD remain unknown. Our objectives were to confirm whether UIP in pSS-ILD could be associated with poor prognosis as recognized in idiopathic interstitial pneumonias, and to determine the prognostic factors. Methods: A retrospective review of medical records identified 33 consecutive patients with pSS-ILD pathologically proven by surgical lung biopsy between November 1998 and November 2008. Clinical, radiological, pathological characteristics and survival rate were analyzed, and compared between patients with NSIP and UIP. The prognostic factors were assessed with Cox proportional hazard model. Results: NSIP (n=22) was the most predominant ILD pattern, and the others were all diagnosed as UIP (n=11). The median follow-up period was 110 months. The five-year survival rate of all patients was 87.3%. The prognosis of patients with UIP was not significantly different from that with NSIP. Multivariate analysis revealed that PaCO₂ (hazard ratio [HR] 1.68 per 1 mm Hg increase, p<0.01), the extent of reticular abnormality on high-resolution CT (HR 4.17 per 1-grade increment, p=0.03), and the severity of fibroblastic foci (HR 9.26 per 1-grade increment, p<0.01) were independent and statistically significant prognostic factors. Conclusions: Survival outcome in UIP was not poorer than in NSIP. Retention of PaCO₂, large extent of reticular abnormality on high-resolution CT, and severe fibroblastic foci were associated with poor prognosis in pSS-ILD.