Diagnostic Yield of Bronchoscopy for Pulmonary Nontuberculous Mycobacterium

Background\nThe\nAmerican Thoracic Society’s guideline of nontuberculous mycobacteria associated\npulmonary disease (NTM PD) suggests bronchoscopy as one of the ways to detect\nnontuberculous mycobacterium ( However, the guideline also acknowledges that l imited\ndata are available on the utility of bronchoscope for the diagnosis of NTM PD. The purpose of\nthis study was to elucidate the diagnostic yield of bronchoscopy for patients suspected for NTM\nPD when sputum cannot reveal NTM. At the same time, we eval uated factors that affected the\nresults of bronchoscopy. Furthermore, we estimated the specificity of bronchoscopy for detecting\nNTM.\nMethod\nThis\nstudy utilized a retrospective cohort study design based on the review of medical records\nand was conducted at St Luke’s International Hospital in Tokyo, Japan. Between January 1,\n2004 and June 30, 2018, among all adult patients who underwent bronchoscopy, two groups\nwere enrolled. Group A included all patients with nodular bronchiectasis pattern on chest\ncomp uted tomography ( findings who could not produce culture positive sputum for NTM\nand therefore underwent bronchoscopy for the diagnoses of NTM PD. Group B comprised of\npatients who received bronchoscopy suspected for lung cancer. Group A was used to eva luate\ndiagnostic yield of NTM PD using bronchoscopy, and group B was employed to measure\nspecificity of bronchoscopy.\nResult\nDiagnostic\nyield of bronchoscopy for NTM PD was 114/205 ( 99 were patients of\npulmonary MAC, remainder were 10 patients of N TM other than MAC, and 5 patients oftuberculosis.\nLogistic regression showed 4 factors associated with NTM PD: examination of the\nupper lobe (odds ratio [ 2.31, 95% confidence interval [ 1.21 4.55), absence of\nparticular bacteria ( 3.35, 95% CI 1.44 8.30), absence of connective tissue disease (\n3.17, 95% CI: 1.25 8.79), and higher total CT scores ( 1.14, 95% CI: 1.03 1.27) Specificity\nof bronchoscopy for NTM PD was 99.2% (900/\nConclusion\nBronchoscopy\nshowed moderate diagnostic yie ld and high specificity for NTM PD.