Presentation (CTI)

OBJECTIVES: To evaluate whether surgeon workforce density or demographic aging is the primary determinant of regional variation in laparoscopic appendectomy adoption across Japan, using nationwide real-world evidence (RWE) data.
METHODS: This ecological study analyzed 547,748 inpatient appendectomies recorded in the Japanese National Database (NDB Open Data) between fiscal years 2014-2023. Prefecture-level appendectomy data were linked with public datasets on surgeon workforce density, aging population structure, and hospital bed supply across all 47 prefectures. Temporal trends in laparoscopic adoption were evaluated using joinpoint regression. Multivariable regression, partial correlation analysis, principal component analysis, and k-means clustering were used to evaluate structural determinants of regional variation.
RESULTS: National laparoscopic appendectomy utilization increased from 58.5% in 2014 to 93.5% in 2023, while inter-prefectural variation substantially narrowed (interquartile range: 15.3 to 5.9 percentage points). Surgeon density varied 2.21-fold across prefectures, aging rate varied 1.71-fold, and hospital bed density varied 2.96-fold. In univariable analysis, surgeon density was positively associated with laparoscopic utilization (r=0.32, P=0.026). However, after simultaneous adjustment for demographic aging and infrastructure, surgeon density was no longer independently associated with laparoscopic adoption (β=1.41, P=0.21), whereas population aging remained a significant negative predictor (β=−2.29, P=0.01). The three structural axes jointly explained 67.0% of variance in per-surgeon appendectomy workload. Cluster analysis identified four distinct regional archetypes reflecting differing demographic and workforce pressures.
CONCLUSIONS: Regional variation in minimally invasive surgical adoption in Japan is more strongly associated with demographic aging than surgeon workforce density. Despite substantial workforce disparities, nationwide convergence of laparoscopic appendectomy was achieved, suggesting that standardized training and reimbursement policies may support equitable diffusion of surgical innovation even in aging societies.