Abstract
OBJECTIVE: To evaluate the relationship between center volume and inpatient mortality after inter-hospital transfer among patients undergoing pediatric cardiac surgery using contemporary real-world data. METHODS: The Kids' Inpatient Database (KID) was queried for cardiopulmonary bypass (CPB) cases (CPB) for years 2016 and 2019. Hospitals were divided into three groups based on terciles of volume: "low": ≤103 cases/year, "mid":104-194 cases/year, and "high": >194 cases/year. Multilevel regression models were created to evaluate the association of volume and inpatient mortality for transferred patients for the entire cohort as well as high-complexity cases. (Risk Stratification for Congenital Heart Surgery (RACHS-2) categories 3,4 and 5). RESULTS: Of 25,749 patients undergoing cases on CPB, 3,511 (13.6%) were preoperative inpatient transfers between hospitals. Compared to direct admissions, unadjusted mortality for patients who were transferred was higher in all groups: 1.7% vs. 5.6% (low-volume), 1.1% vs. 4.6% (mid-volume) and 1.1% vs. 4.9% (high-volume). Compared to low-volume hospitals, inpatient mortality for patients admitted on transfer was not significantly different in mid-volume (OR = 0.85, 95% CI 0.54-1.34, p = 0.483) and high-volume centers (OR = 0.7, 95% CI 0.45-1.12, p = 0.127) for the entire cohort. There was no significant difference in risk-adjusted inpatient mortality for high-complexity cases performed at mid-volume (OR 1.06, p = 0.845, 95% CI (0.62-1.85)) or high-volume hospitals (OR 0.82, p = 0.482, 95% CI (0.48-1.45)). CONCLUSION: Annual CPB case volume may not accurately predict risk-adjusted inpatient mortality for children transferred for heart surgery. Annual case volume alone should not dictate transfer practices in pediatric heart surgery.