Background Previous literature suggested that rheumatoid arthritis (RA) might be a risk factor for nontuberculous mycobacteria pulmonary disease (NTM-PD). However, longitudinal studies did not comprehensively consider potential confounders such as body mass index and smoking status. In addition, the impact of RA seropositivity has not been well elucidated. In this study, we aimed to evaluate the risk of incident NTM-PD in subjects with RA versus age-matched and sex-matched controls, while focusing on the impact of RA serologic status on this association. Methods From the Korean National Health Insurance Service data from 2010 to 2017, we identified 60 315 participants aged ≥20 years with RA and 301 575 without RA who were age-matched and sex-matched 1:5. The participants were followed up from 1 year after RA diagnosis (or the corresponding index date for matched controls) to the date of NTM-PD diagnosis, censored date or 31 December 2019, whichever occurred first. Results During a median 4.5 (IQR, 2.6–6.4) year follow-up, NTM-PD occurred in 0.23% and 0.06% of the RA and matched cohort (incidence: 0.54 and 0.14 per 1000 person-years), respectively. Compared with controls, participants with RA had a 3.11-fold (95% CI 2.50 to 3.88) higher risk of NTM-PD. In the subgroup analysis stratified by seropositivity, seropositive patients with RA had a 3.77-fold (95% CI 3.00 to 4.73) higher risk of NTM-PD than controls, whereas participants with seronegative RA did not have a significantly higher risk (adjusted HR 1.18, 95% CI 0.68 to 2.04). Stratified analyses showed a more prominent association of RA with NTM-PD in males, alcohol drinkers and obese individuals (p<0.05). Conclusion The risk of incident NTM-PD was approximately threefold higher in participants with RA than in matched controls, although the association was significant only for patients with seropositive RA.
Yang et al. (Sat,) studied this question.