Toward quality improvement of cardiovascular surgery in Japan: An estimation of regionalization effects from a nationwide survey

Introduction: In this study, we estimate the effects of regionalization for cardiovascular surgery in Japan, accounting for both its advantages and disadvantages. Methods: This study includes 209,221 procedures from nearly 572 hospitals that conducted cardiovascular surgery in Japan between 2001 and 2004. For the regionalization parameter, hospital surgical volume was divided into four categories: under 10, 10-24, 25-49, and 50-74 average cardiovascular surgeries per year. The effects of regionalization on the 30-day patient mortality rate and an additional travel distance for patients were examined. Results: The 30-day mortality rate for cardiovascular surgery was 4.62% without regionalization. After regionalization, the estimated rate was 4.40% for annual case volumes under 10, 4.28% for volumes 10-24, 3.78% for volumes 25-49, and 3.12% for volumes 50-74. The average annual number of patients who must travel at least an extra 30 km after regionalization are: 0.8 patients for case volumes under 10 (0.001% of total patients), 12.3 patients for volumes 10-24 (0.02% of total), 88.3 patients for volumes 25-49 (0.2% of total), and 179.3 patients for volumes 50-74 (0.3% of total). Conclusion: The results indicate that, after regionalization, the 30-day mortality rate did improve for hospitals with 25-49 and 50-74 annual surgeries. While increased travel times may be critical for patients requiring emergency surgery, the results suggest that low-volume hospitals get relatively few such cases. In many regions, improving the transportation system for emergency cases may be more effective than maintaining a low-volume.