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

To determine the incidence and spectrum of lung involvement in early RA through a structured respiratory assessment and to identify its clinical predictors. 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. 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). 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.