Distinctive Clinical Features of Radiological Pleuroparenchymal Fibroelastosis with Nontuberculous Mycobacterial Pulmonary Disease: A Multicenter Retrospective Cohort Study

Objectives : To compare the characteristics and prognosis of patients with nontuberculous mycobacterial (NTM) pulmonary disease (PD) with pleuroparenchymal fibroelastosis (PPFE) with those of patients with nodular/bronchiectatic (NB) and fibrocavitary (FC) NTM-PD. Methods : This multicenter, retrospective, observational study enrolled 32 patients with NTM-PPFE (median age: 70.5 years, 15 females) from six institutions in Japan from January 2003 to December 2018. Their clinical characteristics, and response to therapy were compared with age- and sex-matched cohorts of patients with non-cavitary NB and cavitary NB/FC NTM-PD. Results : Patients with NTM-PPFE had a lower body mass index and a higher standard NTM-PD therapy initiation rate than patients with other NTM-PD types. Sputum culture conversion rates were comparable between groups; however, patients with NTM-PPFE had a higher incidence of treatment-related adverse events, including optic neuropathy associated with high-dose ethambutol therapy, lower percent predicted forced vital capacity values, higher serum Krebs von den Lungen 6 (KL-6) levels, and poorer treatment outcomes than the other groups. Cox regression revealed that NTM-PPFE was an independent risk factor for death/pneumothorax (adjusted hazard ratio: 35.3, 95% confidence interval: 3.90–4692). Conclusions : NTM-PPFE is a unique NTM-PD phenotype with a poorer prognosis than the NB and FC phenotypes.