Factors Associated with Systemic Lupus Erythematosus-Associated Interstitial Lung Disease and Clinical Outcomes: A...

Background and Objectives: Interstitial lung disease (ILD) is an uncommon but clinically important manifestation of systemic lupus erythematosus (SLE). We aimed to identify factors associated with SLE-ILD, evaluate factors associated with clinical outcomes in established disease, and quantitatively synthesize comparable data. Materials and Methods: PubMed, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials were searched from inception through July 2026. English-language observational studies of adults with SLE reporting factors associated with ILD occurrence or outcomes in established SLE-ILD were eligible. Random-effects meta-analyses were conducted when at least three studies reported comparable data. Results: Eight observational studies were included. Across five studies, patients with SLE-ILD were older than those without ILD (mean difference 8.49 years, 95% confidence interval [CI] 5.52-11.46; p < 0.0001; I² = 66.9%). Across three studies, SLE-ILD was associated with higher odds of Raynaud phenomenon (odds ratio, 3.01; 95% CI, 1.49-6.09; p = 0.0022; I² = 28.8%). Other study-level associations included smoking, serositis, features of overlap connective tissue diseases, selected autoantibodies, and Krebs von den Lungen-6 (KL-6). In established SLE-ILD, baseline forced vital capacity and cohort-specific clinical and imaging features were associated with outcomes, while population-based cohorts linked ILD with increased mortality. Conclusions: Older age and Raynaud phenomenon were the factors most consistently associated with SLE-ILD across the available comparative studies. Because most included studies were observational, these findings should be interpreted as associations rather than evidence of causality. Prognostic evidence remains limited and heterogeneous.