Prevalence and risk factors of non-tuberculous mycobacterial pulmonary isolates and infection in interstitial lung disease associated with systemic autoimmune disease.

OBJECTIVES:Non-tuberculous mycobacterial (NTM) lung disease (NTM-LD) prevalence is increasing worldwide. In this study, we aimed to evaluate the clinical significance of NTM pulmonary isolates (NTM-PI) and NTM-LD in patients with systemic autoimmune disease (SAD) who had a concurrent interstitial lung disease (ILD) diagnosis. METHODS:We retrospectively identified patients with SAD who had a concurrent ILD diagnosis (SAD-ILD) and from whom clinically indicated sputum specimens were collected for NTM culture between 2003 and 2018 at a tertiary referral hospital. We analysed the prevalence and risk factors of NTM pulmonary isolates (NTM-PI; ≥1 positive culture) and NTM-LD (≥2 positive cultures). RESULTS:This study included 258 patients. Rheumatoid arthritis and Sjögren's syndrome were the most common SADs (32.2% and 26.7%, respectively). The NTM-negative subgroup had 204 patients (79.1%) and the NTM-PI subgroup had 54 patients (20.9%). In the NTM-PI subgroup, 33 patients had one NTM positive set of specimens (NTM 1+, 12.8% of the entire sample) and 21 had NTM-LD (8.1% of the entire sample). In a multivariable analysis, chronic kidney disease (CKD; adjusted odds ratio [aOR]: 3.10 [1.53, 6.29]) and chronic obstructive pulmonary disease (COPD; aOR: 2.59 [1.16, 5.78]) were significantly associated with NTM-PI. For NTM-LD, CKD (aOR: 2.79 [1.00, 7.76]) and COPD (aOR: 3.70 [1.23, 10.72]) remained significant risk factors. CONCLUSIONS:In patients with SAD-ILD, the NTM-PI and NTM-LD prevalence rates were 20.9% and 8.1%, respectively. COPD and CKD were independent risk factors of both NTM-PI and NTM-LD. Previous use of biological agents was associated with NTM-PI.