Bronchiectasis is as crucial as interstitial lung disease in the severe pneumonia that occurs during treatment with biologic DMARDs in rheumatoid arthritis: a retrospective cohort study in a single facility.

Interstitial lung disease (ILD) carries a risk for severe pneumonia in patients with rheumatoid arthritis (RA). Bronchiectasis, another risk of severe pneumonia, has not been well elucidated in RA. We investigated the types of respiratory diseases in RA and correlated them to severe pneumonia during the course of treatment using biologic DMARDs (bDMARDs), with special attention to bronchiectasis and ILD. RA patients were examined by computed tomography before starting bDMARDs and divided into three groups: normal, bronchiectasis and ILD. The log-rank test and Dunnett's multiple comparisons test were employed for the statistical analysis. Among 424 patients, 350 were categorized as normal, 32 as having bronchiectasis, and 42 as having ILD. Two in the normal group, three in the bronchiectasis group and four in the ILD group developed severe pneumonia. The log-rank test showed a significant difference among the three groups (p < 0.0001). The pneumonia-free rates in the bronchiectasis and ILD groups were significantly lower than the normal group, respectively, with Dunnett's multiple comparison test (p < 0.0001). This study suggests that the bronchiectasis that occurs in RA carries a risk of severe pneumonia during treatment with bDMARDs that is comparable to ILD.