Risk factors of incident lung diseases and the impact of DMARDs in rheumatoid arthritis patients: a longitudinal study

We aimed to investigate the impact of clinical characteristics and therapy on rheumatoid arthritis (RA)-related lung diseases. The retrospective cohort consisted of 1,207 inpatients at baseline. RA-related lung diseases included interstitial lung disease (ILD), bronchiectasis, pleural effusion, and pulmonary arterial hypertension. Kaplan-Meier method was used to measure the cumulative incidence curve. Cox regression was conducted to evaluate the associations between RA-related lung diseases and risk indicators. Logistic regression was employed to examine the impact of drugs. The study identified 145 cases of RA-related lung diseases (34.2/1,000 person-years; 95% CI: 28.6–39.7) and 98 RA-ILD cases (22.5/1,000 person-years; 95% CI: 18.0–26.9) over 3.5 years. The cumulative incidence of RA-related lung diseases increased continuously over time, accelerating after 10 years of RA and age 55. RA-related lung diseases was independently associated with older age at RA onset (per 10 years, hazard ratio [HR] = 1.22, 95% confidence interval [CI]: 1.04–1.42), longer RA duration (per 10 years, HR = 1.43, 95% CI: 1.15–1.77), higher Rheumatic Disease Comorbidity Index (HR = 1.22, 95% CI: 1.08–1.39), prior pulmonary infections (HR = 2.26, 95% CI: 1.58–3.24), and systemic lupus erythematosus comorbidity (HR = 2.36, 95% CI: 1.35–4.13). After adjustment, ever-use of methotrexate demonstrated a significant protective association against both RA-related lung diseases (odds ratio [OR] = 0.64, 95% CI: 0.44–0.92) and RA-ILD (OR = 0.54, 95% CI: 0.35–0.83). Similarly, biologic or targeted synthetic disease modifying antirheumatic drugs (b/tsDMARDs) were also found protective (OR = 0.59, 95% CI: 0.35–0.99). This study identifies several clinically significant risk factors for RA-related lung diseases, while demonstrating protective effects of methotrexate and b/tsDMARDs.