Association Between Volume and Outcomes of Infective Endocarditis Surgery: A Nationwide Cohort Study

Background To determine the relationship between hospital surgical volume and mortality risk and valve repair rate in infective endocarditis (IE) surgery. Methods Using the Taiwan National Health Insurance Research Database (NHIRD), 3873 patients were identified who underwent surgery between 2000 and 2013. The cumulative hospital volume of valve surgery for IE was calculated, and patients were divided into 4 subgroups according to the quartile. Outcomes were mortality and valve repair rate and the cut point of referral excellence. Results The distribution of IE surgery has been shifting to lower volume hospitals over the years. The global disease severity (Charlson’s Comorbidity Index score [CCI score]) of patients was greater in the lowest volume hospital than in the highest volume hospital (2.4 vs. 2.0). The crude in-hospital mortality rate was 15.8% and 9.4% for the lowest and highest volume hospitals, respectively, with a significant difference (adjusted odds ratio: 1.86, 95% confidence interval: 1.22–2.85) after adjustment of baseline characteristics including the CCI score. The mitral valve (MV) repair rate increased with the increase in cumulative volume. During a mean follow-up period of 4.4 years, 324 (41.9%) and 254 (30.9%) patients died in the lowest and highest volume subgroups, respectively, and the difference was significant (adjusted hazard ratio: 1.59, 95% CI: 1.21–2.10). Conclusions A higher cumulative volume of IE surgery is associated with a lower risk of mortality and a higher likelihood of successful MV repair. Therefore, interfacility transfer to a high-volume hospital may improve outcomes of IE surgery.