Supplementary Material for: Hospital Volume and Mortality following Diagnostic Bronchoscopy in Lung Cancer Patients: Data from a National Inpatient Database in Japan

Background: Recent advances in bronchoscopy utilizing endobronchial ultrasound (EBUS) as well as lung cancer therapy may have driven physicians to perform diagnostic bronchoscopy (DB) for high-risk patients. Objectives: The aim of this study was to clarify the relationship between hospital volume (HV) and outcomes of DB. Methods: We collected data on inpatients with lung cancer who underwent DB from July 2010 to March 31, 2014. The annual HV of DB was classified as “very low” (≤50 cases/year), “low” (51–100 cases/year), “high” (101–300 cases/year), or “very high” (> 300 cases/year). The primary outcome was all-cause 7-day mortality after DB. Multivariable logistic regression fitted with a generalized estimation equation was performed to evaluate the association between HV and all-cause 7-day mortality after DB, adjusted for patient background factors. Results: We identified a total of 77,755 eligible patients in 954 hospitals. All-cause 7-day mortality was 0.5%. Compared with the low-volume group, 7-day mortality was significantly lower in the high-volume group (odds ratio [OR] = 0.69, 95% confidence interval [CI]: 0.52–0.92, p = 0.010), and a similar trend was shown in the very-high-volume group (OR = 0.67; 95% CI: 0.43–1.05, p = 0.080). Radial EBUS with the guide sheath method and EBUS-guided transbronchial needle aspiration showed a significantly lower 7-day mortality. Conclusions: All-cause 7-day mortality was inversely associated with HV. The risk of DB in patients with lung cancer should be recognized, and the exploitation of EBUS may help reduce mortality after DB.