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Background and Objective: Interstitial lung disease (ILD) can occur as a manifestation of rheumatoid arthritis (RA) at various times in the disease course. We aimed to identify factors associated with early versus late onset RA‐ILD and how the timing of RA‐ILD influenced surgical lung biopsy completion and mortality. Methods: We performed a retrospective observational study using health services data from Ontario, Canada. We identified RA cases between 2000 and 2020 using the Ontario Rheumatoid Arthritis Database. RA‐ILD diagnosis required repeat physician visits for ILD, with early RA‐ILD defined as within 1 year of RA diagnosis. We performed multivariable logistic regression to identify factors associated with early RA‐ILD and surgical lung biopsy completion, and multivariable cox‐proportional hazards regression to evaluate the association of early versus late RA‐ILD on all‐cause and RA‐ILD related mortality. Results: In total, we identified 3717 cases of RA‐ILD. Older age at RA diagnosis [OR 1.04 (95%CI 1.03–1.05), p < 0.0001], female sex [OR 1.16 (95%CI 1.01–1.35), p = 0.04] and immigrating to Ontario [OR 1.70 (95%CI 1.35–2.14), p < 0.0001] was associated with early RA‐ILD. Patients with early versus late RA‐ILD experienced similar odds of undergoing a surgical lung biopsy [OR 1.34 (95%CI 0.83–2.16), p = 0.23]. Early RA‐ILD was associated with increased all‐cause mortality [HR 1.17 (95%CI 1.07–1.29), p = 0.0009], primarily driven by an increase in RA‐ILD related mortality [HR 1.45 (95%CI 1.19–1.76), p = 0.0003]. Conclusion: Age at RA onset, female sex and immigration status are associated with early RA‐ILD. Patients with early RA‐ILD experience increased all‐cause and RA‐ILD related mortality after adjusting for demographics and comorbidities. We show that females, immigrants and patients diagnosed with RA at an older age, are at increased risk for early RA‐ILD (within 1‐year of RA diagnosis). Early RA‐ILD carries an increased risk for RA‐ILD related mortality, which may justify a more aggressive approach to disease monitoring and treatment. [ABSTRACT FROM AUTHOR]

Background and objective: Rheumatoid arthritis (RA) is a frequent cause of interstitial lung disease (ILD); however, the impact of rheumatoid factor and anti‐citrullinated peptide antibody seropositivity in ILD without connective tissue disease (CTD) is unclear. We examined the association of seropositivity with ILD progression, mortality and response to immunosuppression in non‐CTD ILD. Methods: A total of 1570 non‐CTD patients (with idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, interstitial pneumonia with autoimmune features or unclassifiable ILD) and 181 RA‐ILD patients were included from a prospective registry. Longitudinal forced vital capacity (FVC), transplant‐free survival and incidence of progressive fibrosing‐ILD (PF‐ILD) were compared between seronegative non‐CTD ILD (reference group), seropositive non‐CTD ILD and RA‐ILD using linear mixed‐effect and Cox proportional hazards models adjusted for age, sex, smoking pack‐years and baseline FVC. Interaction between seropositivity and immunosuppression on FVC decline was assessed in patients with ≥6 months of follow‐up before and after the treatment. Results: Two hundred and seventeen (13.8%) patients with seropositive non‐CTD ILD had similar rates of FVC decline and transplant‐free survival compared to seronegative non‐CTD ILD, but more frequently met the criteria for PF‐ILD (hazard ratio [HR] = 1.35, p = 0.004). RA‐ILD had slower FVC decline (p = 0.03), less PF‐ILD (HR = 0.75, p = 0.03) and lower likelihood of lung transplant or death (HR = 0.66, p = 0.01) compared to seronegative non‐CTD ILD. No interaction was found between seropositivity and treatment on FVC decline in non‐CTD ILD. Conclusion: Seropositivity in non‐CTD ILD was not associated with improved outcomes or treatment response, highlighting the importance of other disease features in determining prognosis and predicting response to immunosuppression. We show that rheumatoid factor and anti‐citrullinated peptide antibody are not associated with outcomes or response to immunosuppression in patients with interstitial lung diseases not due to connective tissue disease, indicating the need for future studies to test the prognostic impact of other clinical and radiological features that may predict response to therapy. See relatedEditorial [ABSTRACT FROM AUTHOR]