Relationship between hospital volume and risk-adjusted mortality rate following percutaneous coronary intervention in Korea, 2003 to 2004

Objective: There have been a large number of studies that have investigated the relationship between outcomes and provider volume for a wide variety of medical conditions and surgical conditions. The objective of this study was to explore the relation between hospital volume and risk-adjusted mortality following percutaneous coronary intervention between 2003 and 2004 in Korea. Methods: This is a retrospective analysis of database in National Health Insurance Review & Assessment Service and Korean National Statistical Office. The study data set confined to the ICD-10 diagnosis and procedure codes that were recorded in the National Health Insurance Review Agency. Risk modeling was performed through logistic regression and validated with cross-validation. The statistical performance of the developed model was evaluated using c-statistics, R2, and Hosmer-Lemeshow statistic. Crude and risk-adjusted 30-day mortality was evaluated among patients who underwent Percutaneous Coronary Intervention (PCI) between 2003 and 2004 at low (less 200 cases/year), medium (200~399 cases/year), and high (400 cases or more/year) PCI volume hospitals. Results: The final risk-adjustment model consisted of ten risk factors for 30-day mortality. These factors were found to have statistically significant effects on patient mortality. The c-statistic and Hosmer-Lemeshow χ2 goodness-of-fit test and the model’s performance were good [R2=0.147, c-statistic 0.823, 4.1037 (p=0.8476)]. A total number of 60 low-volume hospitals (9.071 patients) and 27 medium-volume hospitals (15.623 patients) and 15 high-volume hospitals (19.669 patients) were included. Crude 30-day mortality rate was 1.4%, 1.1%, and 1.0% (p=0.0106) in each volume hospitals. But risk-adjusted mortality rate was not significantly different among three groups (1.3%, 1.0%, and 1.1% in each volume hospitals). Conclusion: Although we found a significant different crude 30-day mortality rates according to hospital PCI volume, but did not find a relationship between hospital volume and 30-day risk-adjusted mortality rates following PCI in Korea.