A retrospective study of factors associated with treatment decision for nontuberculous mycobacterial lung disease in adults without altered systemic immunity.

Background: Nontuberculous mycobacteria (NTM) lung diseases are increasingly recognized as chronic opportunistic infections, occurring in individuals with a wide variety of underlying conditions. In the absence of systemic immunodeficiency, decision of NTM lung disease treatment must relies on a careful risk/benefit assessment, given the requirement of long-term administration of multidrug therapies supported by limited evidence. The primary objective was to identify the factors associated with anti-NTM treatment initiation. Clinical and radiological outcome upon treatment were studied.

Methods: This retrospective, single center study (2013-2016, 45 months) addressed the criteria supporting treatment decision among adults with NTM lung disease without systemic immunodeficiency at our institution, with the assigned goal to harmonize the practice. All patients matched the current international definitions of NTM lung disease according to the American Thoracic Society criteria. Factors associated with anti-NTM treatment were investigated by conditional logistic regression. Clinical and radiological outcomes of treated and untreated NTM-disease cases were examined. Mortality rate was assessed. An expert radiologist conducted a blinded computed tomography (CT)-scan review of the treated and untreated patients.

Results: Among 51 cases of NTM lung diseases, 25 (49%) received anti-NTM treatment. In univariate analysis, a body mass index (BMI) < 18 kg/m (odds ratio (OR), 4.2 [95% confidence interval (CI) 1.2-15.2]; p = 0.042), hemoptysis (OR, 11.8 [95% CI 1.35-12.9]; p = 0.026), excavation(s) (OR, 4.8 [95% CI 1.4-16.4], p = 0.012), prior anti-NTM treatment (OR, 5.65 [95% CI 1.06-29.9]; p = 0.042), Aspergillus spp. co-infection (OR, 6.3 [95% CI 1.8-22.2]; p = 0.004) were associated with treatment initiation. In multivariate analysis, Aspergillus spp. co-infection was the only independent determinant of treatment initiation (OR, 5.3 [95% CI 1.1-25.4]; p = 0.036). Twenty-one (81%) patients received ≥3 anti-NTM drugs. Median treatment duration and follow-up were 36.3 (interquartile range [IQR], 13.1-64.4) weeks and 17.1 (IQR, 8.7-27.1) months, respectively. Regarding radiological outcome, 85 CT-scans were reviewed, showing similar rates of regression or stabilization in treated and untreated patients. Overall mortality rate was not different in treated and untreated patients.

Conclusion: The most relevant variable associated with anti-NTM treatment initiation was Aspergillus spp. co-infection. Radiological regression or stabilization of pulmonary lesions was not different between the treated and untreated patients.