Prognostic impact of rheumatoid arthritis on respiratory-related mortality in non-tuberculous mycobacterial pulmonary disease

Objectives The prognostic implications of rheumatoid arthritis (RA) in patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD) remain unclear. This study aimed to evaluate the impact of RA on survival outcomes.Methods We conducted a retrospective cohort study of 1420 patients newly diagnosed with NTM-PD between 2012 and 2024. Among them, 66 (4.6%) had RA, including 55 who developed NTM-PD after RA onset. These 55 patients (RA group) were compared with 1354 without RA (non-RA group). Respiratory-related mortality was assessed using Cox regression and propensity score matching. To explore mechanisms underlying the excess mortality associated with RA, we conducted sequential Cox regression with stepwise adjustment and quantified attenuation of the RA effect on the log-hazard scale.Results RA was an independent predictor of respiratory-related death in multivariable Cox analysis (HR 4.30, 95% CI 2.17 to 8.52). Five-year survival was significantly lower in the RA group than in the non-RA group (74.7% vs 92.9%, log-rank p<0.001) and remained inferior after matching (p=0.029). Sequential adjustment demonstrated substantial attenuation of the RA effect after accounting for interstitial lung disease (ILD), with the HR decreasing from 3.25 to 2.44 (24.5% attenuation), and to 2.09 after adjustment for systemic inflammation burden reflected by C-reactive protein (37.5% attenuation).Conclusion RA is an independent predictor of respiratory-related mortality in patients with NTM-PD. This excess risk is partly explained by ILD and systemic inflammation burden. These findings highlight structural and systemic pathways contributing to poor prognosis, underscoring the need for comprehensive management in this high-risk population.