Disease Progression in Patients With Nontuberculous Mycobacterial Lung Disease of Nodular Bronchiectatic (NB) Pattern: The Roles of Cavitary NB and Soluble Programmed Death Protein-1.

Background: In patients with nodular bronchiectatic (NB) nontuberculous mycobacterial lung disease (NTM-LD), risk factors for disease progression have not been clearly investigated. The roles of cavitary NB and soluble programmed death protein-1 (sPD-1), an immune-related biomarker, in the disease course of NB NTM-LD remain unknown.

Methods: Patients with NB NTM-LD were enrolled from 2 medical centers in 2014-2020. We identified cavitary NB, measured sPD-1 levels, and analyzed factors associated with cavitary NB and predictors for disease progression of NB NTM-LD.

Results: Of 120 cases of NB NTM-LD, 87 (72.5%) were caused by Mycobacterium avium complex. sPD-1 levels were lower in 13 (10.8%) patients with cavitary NB than in noncavitary patients (P = .020). Over 1.41 ± 1.43 years of follow-up, 12 (92.3%) patients in the cavitary and 66 (61.7%) in the noncavitary group developed disease progression (P = .032). In multivariable analysis, body mass index (BMI [kg/m2]; adjusted hazard ratio [aHR], .895 [95% confidence interval, .811-.988]), sputum smear grade (aHR, 1.247 [1.014-1.534]), cavitary NB (aHR, 2.008 [1.052-3.834]), and sPD-1 (per 10-pg/mL increase; aHR, .889 [.816-.967]) were predictive for disease progression. Notably, sPD-1 showed a dose-dependent association with disease progression (sPD-1 ≤23.5 pg/mL; aHR, 3.306 [1.664-6.567]; sPD-1: 23.6-53.7 pg/mL; aHR, 2.496 [1.390-4.483]) compared with the reference (sPD-1 >53.7 pg/mL).

Conclusions: Patients with NB NTM-LD and low sPD-1, low BMI, high smear grade, and cavitary NB were at high risk for disease progression. sPD-1 was low in patients with cavitary NB phenotype and dose-responsively associated with disease progression.