Effect of hospital and surgeon volume on postoperative outcomes after distal gastrectomy for gastric cancer based on data from 145,523 Japanese patients collected from a nationwide web-based data entry system

Background: Despite interest in surgeon and hospital volume effects on distal gastrectomy, clinical significance has not been confirmed in a large-scale population. We studied to clarify the effects of surgeon and hospital volume on postoperative mortality after distal gastrectomy for gastric cancer among Japanese patients in a nationwide web-based data entry system. Methods: We extracted data on distal gastrectomy for gastric cancer from the National Clinical Database between 2011 and 2015. The primary outcome was operative mortality. Hospital volume was divided into 3 tertiles: low (1–22 cases per year), medium (23–51) and high (52–404). Surgeon volume was divided into the 5 groups: 0–3, 4–10, 11–20, 21–50, 51 + cases per year. We calculated the 95% confidence interval (CI) for the mortality rate based on odds ratios (ORs) estimated from a hierarchical logistic regression model. Results: We analyzed 145,523 patients at 2182 institutions. Operative mortality was 1.9% in low-, 1.0% in medium- and 0.5% in high-volume hospitals. The operative mortality rate decreased definitively with surgeon volume, 1.6% in the 0–3 group and 0.3% in the 51 + group. After risk adjustment for surgeon and hospital volume and patient characteristics, hospital volume was significantly associated with operative morality (medium: OR 0.64, 95% CI 0.56–0.73, P < 0.001; high: OR 0.42, 95% CI 0.35–0.51, P < 0.001). Conclusions: We demonstrate that hospital volume can have a crucial impact on postoperative mortality after distal gastrectomy compared with surgeon volume in a nationwide population study. These findings suggest that centralization may improve outcomes after distal gastrectomy.