Risk Factors and Prognostic Effects of Aspergillosis as a Complication of Nontuberculous Mycobacterial Pulmonary Disease: A Nested Case–Control Study

ABSTRACT Objective The global prevalence of nontuberculous mycobacterial pulmonary disease (NTM‐PD) has been steadily increasing. A few small retrospective studies have reported a poor prognosis associated with chronic pulmonary aspergillosis (CPA) as a complication of NTM‐PD. Furthermore, the prognostic impact of CPA may have been inadequately assessed due to differences in background factors. This study aimed to identify the risk factors for CPA in NTM‐PD and compare the risk of in‐hospital mortality between patients with and without aspergillosis. Methods Data were obtained from a large‐scale claims database. Patients with NTM‐PD who met the inclusion criteria and those who developed CPA after the NTM diagnosis were identified. The incidence of CPA was evaluated, and risk factors were identified using multiple logistic analyses. Mortality rates were evaluated and compared between patients with and without aspergillosis after adjusting for background CPA risk factors. Results The incidence of CPA was 2.29% (265/11,587). The identified risk factors included male sex, chronic respiratory failure, asthma, interstitial pneumonia, pulmonary tuberculosis sequelae and systemic corticosteroid use. A total of 219 patients with CPA were matched with control cases using propensity scores based on age and identified risk factors for CPA. The adjusted hazard ratio for in‐hospital mortality was 2.6 (95% CI: 1.8–3.9). Conclusions CPA as a complication of NTM‐PD is associated with significantly higher mortality rates. Clinicians should consider the necessity of promptly diagnosing CPA in patients with NTM‐PD and the associated risk factors.