Interstitial Lung Disease and Pulmonary Damage in Primary Sjögren's Syndrome: A Systematic Review and Meta-Analysis

Background: Pulmonary lung involvement is the most common extra-glandular manifestation in patients with primary Sjogren's syndrome (pSS), leading to a worsening of the patient's prognosis. To date, different studies have assessed the prevalence of pulmonary involvement and interstitial lung disease (ILD) in pSS patients with different results. Methods: We performed a systematic literature review and meta-analysis on ILD pooled prevalence in pSS according to the PRISMA and MOOSE guidelines. Furthermore, we explored the pooled prevalence of the two main presentations of pSS-ILD, nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP). Results: We analysed the pSS-ILD prevalence in 30 studies including 8255 pSS patients. The pSS-ILD pooled prevalence was 23% (95% CI: 16-30). For NSIP, we found a pooled prevalence of 52% (CI 41-64), and for UIP we found a pooled prevalence of 44% (CI: 32-55). Regarding the meta-regression analysis, male gender, DLco value, country, and HRCT seem to contribute to the ILD presence. Conclusions: At least 20% of pSS patients have a comorbid ILD, usually NSIP. Male gender and alteration in DLco value may be considered the most important independent factors supporting an active search of lung complications during the clinical history of pSS patients.