Geographic variation in bronchoscopy use across Japan: A nationwide analysis using administrative claims data.

Bronchoscopy is a widely used diagnostic procedure in respiratory medicine. Despite recent advances in techniques and an ongoing aging population, detailed information regarding current bronchoscopy procedural patterns and practice settings remains limited for Japan. We analyzed bronchoscopic procedure volumes and settings across 47 Japanese prefectures over the 2023 fiscal year, using NDB Open Data. A total of 177,317 procedures were performed, with a nationwide rate of 142.6 per 100,000 population. Of these, 78.8 % were conducted during inpatient care. The procedural rate and proportion of inpatient cases varied substantially by prefecture. No significant correlation was observed between population aging rate and procedure volume, but a moderate positive correlation was identified between procedure volume and the density of board-certified respiratory specialists (Spearman's ρ = 0.517, p < 0.001). This nationwide analysis highlights the substantial regional variations in bronchoscopy practices across Japan and suggests a possible role of specialist distribution in determining access to the procedure.