Rationale: The clinical features and prognosis of nontuberculous mycobacterial (NTM) pleuritis and pleural effusion combined with NTM lung disease remain unclear. Objectives: To investigate the clinical features and prognosis of NTM pleuritis. Methods: This retrospective observational study included patients with NTM pleuritis from January 2001 to June 2018 across eight hospitals in Japan. NTM pleuritis was defined by a positive NTM culture of pleural effusion samples. We matched patients with Mycobacterium avium complex (MAC) lung disease (MAC-LD) without pleuritis by sex and age to obtain comparative data and investigated the association between clinical parameters and the prognosis. Results: We identified 64 patients with NTM pleuritis (median age, 73 yr; 37 female patients). The median follow-up duration was 11 months, and 27 patients died. Patients with MAC pleuritis had a significantly lower survival rate than matched patients with MAC-LD without pleuritis. Multivariate analysis revealed that pleuritis (adjusted hazard ratio, 6.99; 95% confidence interval [CI], 2.58-19.00) and underlying pulmonary diseases (adjusted hazard ratio, 3.01; 95% CI, 1.44-6.28) were independently associated with all-cause mortality in patients with MAC-LD. Conclusions: The prognosis of MAC pleuritis is poorer than that of MAC-LD without pleuritis. Pleuritis is an independent prognostic factor in patients with MAC-LD.
Keywords: Mycobacterium avium complex; nontuberculous mycobacteria; pleural effusion.