Risk of Serious Infection in Patients With Rheumatoid Arthritis–Associated Interstitial Lung Disease or Bronchiectasis: A Comparative Cohort Study

Objective To investigate the association between rheumatoid arthritis–associated lung disease (RA‐LD) and serious infection risk. Methods We conducted a retrospective cohort study using the Massachusetts General Brigham Biobank (Boston, MA, USA), comparing RA‐LD with patients with RA without lung disease (RA‐no LD), matched by age, sex, and RA duration. Cases of RA‐LD were verified by medical record review and chest imaging for clinically apparent RA‐associated interstitial lung disease (RA‐ILD) and/or RA‐associated bronchiectasis (RA‐BR). The primary outcome was serious infection. Incidence rates and propensity score–adjusted subdistribution hazard ratios (sdHRs) were calculated using Fine and Gray models to account for competing risk of death. Results Among 221 patients with RA‐LD (151 RA‐ILD and 70 RA‐BR) and 980 RA‐no LD comparators, RA‐LD had a significantly higher serious infection risk compared with RA‐no LD comparators (55.8 vs 25.8 per 1,000 person‐years; sdHR 1.60; 95% confidence interval CI 1.20–2.12). The increased risk remained significant for those with RA‐ILD (sdHR 1.79; 95% CI 1.33–2.41) but not for RA‐BR (sdHR 1.19; 95% CI 0.72–1.97). Anatomic sites of infection that were more common in RA‐LD included pulmonary, skin and soft tissue, and ear, nose, and throat; RA‐LD was associated with various pathogen types, including virus, bacteria, fungus, and mycobacteria. Specific pathogens with higher frequency in cases of RA‐LD, particularly among RA‐BR, included influenza virus, respiratory syncytial virus, Staphylococcus , Pseudomonas , and nontuberculous mycobacteria. Conclusion RA‐LD, particularly RA‐ILD, is associated with a significant increased risk of serious infection across anatomic sites and diverse pathogen types. RA‐BR is associated with increased pulmonary infections. Prospective studies and trials are needed to clarify optimal approaches to treat patients with RA‐LD and reduce infection risk. image