Objectives To compare mortality risks in patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) and patients with RA without ILD. Design Matched cohort study. Setting The study was conducted in Denmark, using nationwide, prospectively collected data. Participants Among patients with RA diagnosed between 2004 and 2016, 679 patients with RA-ILD were matched for birth year, gender and age at RA diagnosis with 11 722 patients with RA but without ILD. Main outcome measures Mortality risks were assessed using Kaplan-Meier mortality curves, and hazard rate ratios (HRRs) for death were estimated using Cox proportional hazards regression models. Results The number of prevalent RA patients more than doubled from 15 352 to 35 362 individuals during the study period. RA-ILD was seen in 2.2% of incident RA patients. 34.0% of RA-ILD cases were diagnosed within 1 year prior to and 1 year after the RA diagnosis. One-year mortality was 13.9% (95% CI, 11.4% to 16.7%) in RA-ILD and 3.8% (95% CI, 3.5% to 4.2%) in non-ILD RA, 5-year mortality was 39.0% (34.4% to 43.5%) and 18.2% (17.3% to 19.1%) and 10-year mortality was 60.1% (52.9% to 66.5%) and 34.5% (32.8% to 36.1%), respectively. The HRRs for death were 2 to 10 times increased for RA-ILD compared with non-ILD RA, irrespective of follow-up period. Stratified analysis showed that the HRR for death was highest in the first months after the diagnosis of RA-ILD was made, especially in patients diagnosed with RA before diagnosis of ILD. HRR was higher in males and in patients without comorbidity as assessed by the Charlson Comorbidity Index. Conclusions ILD is a serious complication in RA, with a significantly increased mortality compared with a large matched cohort of RA comparisons without ILD.

Interstitial lung disease (ILD) is a serious complication of rheumatoid arthritis (RA) contributing to significantly increased morbidity and mortality. Other respiratory complications, such as chronic obstructive pulmonary disease and bronchiectasis, are frequent in RA. Infections and drug toxicity are important differential diagnoses and should be considered in the diagnostic work-up of patients with RA presenting with respiratory symptoms. This review provides an overview of the epidemiology and pathogenesis of RA-ILD, the radiological and histopathological characteristics of the disease as well as the current and future treatment options. Currently, there is no available evidence-based therapy for RA-ILD, and immunosuppressants are the mainstay of therapy. Ongoing studies are exploring the role of antifibrotic therapy in patients with progressive fibrotic ILD, which may lead to a new treatment approach for subgroups of patients with RA-ILD.

Introduction: Interstitial lung disease (ILD) is a serious extraarticular manifestation of rheumatoid arthritis (RA), but no evidence-based therapy exists. Ongoing studies investigate the role of antifibrotic therapies for progressive fibrosing ILD (PF-ILD), including RA-ILD. The aim of the present study was to investigate the frequency of PF-ILD and the clinical characteristics of RA-ILD in a well-characterised, population-based cohort. Methods: We identified patients with RA-ILD diagnosed and followed at the ILD referral centre in Aarhus, Denmark, from 2004 to 2016. Adjusted hazard rate ratios for death were estimated using Cox regression models. The presence of PF-ILD was assessed using recently proposed definitions of relative forced vital capacity (FVC) decline ≥10%, relative diffusion capacity of the lung for carbon monoxide (DLco) decline ≥15% or worsening symptoms or a worsening radiological appearance accompanied by a ≥5 to <10% FVC decline. Results: We identified 102 patients with RA-ILD, and 52% had PF-ILD. Mean follow-up was 3.8 years and median survival was 7.1 years. Thirty-eight patients died during follow-up, and most deaths were from respiratory causes. Predictors of mortality in a multivariate model were DLco and high titres of IgM rheumatoid factor. Conclusion: PF RA-ILD was common and the associated mortality was high.