Prevalence and incidence of interstitial lung diseases in systemic lupus erythematosus: systematic review and meta-analyses.

OBJECTIVE: Our objective is to estimate the prevalence and incidence of interstitial lung diseases (ILDs) among adults with systemic lupus erythematosus (SLE) and to explore possible differences in reported prevalence and incidence of SLE-ILDs between clinical observational and register-based studies. METHOD: EMBASE, MEDLINE, Cochrane Library and Scopus were searched for eligible studies investigating SLE-ILDs prevalence and/or incidence. Risk of bias was assessed using the Joanna Briggs Institute Prevalence Critical Appraisal Tool. Data were extracted in a predefined Excel spreadsheet by two reviewers independent and blinded to each other. Pooled weighted prevalences and incidences were calculated with corresponding 95% CIs, visualised in forest plots. Heterogeneity was assessed with I2 test. RESULTS: Ninety-eight studies comprising 155 964 participants were included in the systematic review and meta-analyses. The pooled weighted SLE-ILDs prevalence was 11.0% (9.0% to 13.0%), with substantial heterogeneity (I²=99.9%), and 18% when identifying SLE-ILDs with chest high-resolution CT (HRCT) scans. Clinical observational studies reported a higher prevalence of 25.0% (19.0% to 31.0%) compared with register-based studies 7.0% (5.0% to 8.0%). The incidence analysis was based on three registry-based studies and estimated an incidence of 4.9 per 1000 person-years (-0.5 to 10.3) with substantial heterogeneity (I² = 99.8%). CONCLUSION: ILDs appear to be a prevalent manifestation in SLE with a pooled prevalence estimate of 11.0%, although this estimate should be interpreted with caution due to substantial heterogeneity across studies. HRCT-based studies reported a higher prevalence (18.0%), suggesting that diagnostic modality influences prevalence estimates. The incidence estimate (4.9 per 1000 person-years) should be interpreted as exploratory because it was based on only three registry-based studies. Overall, the findings suggest that ILD may be more common in SLE than previously assumed, highlighting the importance of awareness of pulmonary manifestations. We found the prevalence to be higher in clinical observational studies than register-based studies. PROSPERO REGISTRATION NUMBER: CRD420250642237.