Incidence and spectrum of primary respiratory disease throughout the course of rheumatoid arthritis: implications of structured repeated evaluation for detection and risk-factor analysis.

OBJECTIVE: To determine the incidence and spectrum of lung involvement in early RA through a structured respiratory assessment and to identify its clinical predictors. METHODS: A retrospective study was conducted in a cohort of 204 early RA patients screened for lung involvement at RA onset and during follow-up. Cumulative incidence (CI) at four and eight years, incidence rate (IR), and frequency were calculated for the different manifestations identified. Cox regression was used to assess potential risk factors. RESULTS: Pulmonary involvement was identified in 89 of 204 patients (43.6%). The CI increased from 17.5% at four years to 25.2% at eight years. The IR was 42.0 per 1,000 person-years among patients without prior lung disease, rising to 50.2 when including pre-existing cases. The screening strategy proved effective, detecting asymptomatic lung involvement in one-quarter of patients (51/204). Interstitial lung disease (ILD) (22.5%) and bronchiectasis (22.1%) were the most frequent manifestations, followed by follicular bronchiolitis (FB) (7.8%), pulmonary nodules (5.4%), pleural disease (3.4%), and obliterative bronchiolitis (OB) (1%). The IRs were 20.4 for bronchiectasis, 16.2 for ILD, 6.9 for FB, 4.9 for nodules, 2.0 for pleural disease, and 1.0 for OB. Bronchiectasis showed the highest CI (8.8% at four years and 12.9% at eight years), followed by ILD (7.5% and 11.6%). Age at RA onset (≥ 60 years) was independently associated with overall lung involvement (HR 2.22, 95% CI 1.20–4.11), ILD (HR 3.36, 95% CI 1.23–9.20), and bronchiectasis (HR 2.42, 95% CI 1.07–5.43). Male sex was associated with ILD (HR 5.11, 95% CI 1.52–17.13). CONCLUSIONS: Proactive screening identified a high incidence of ILD and airway disease in early RA, supporting routine pulmonary evaluation to attempt to optimise early detection and patient outcomes.