Center Volume Not Associated with Survival Benefit of Inter-hospital Transfer for Pediatric CardiacSurger.

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.