Risk Adjustment for Neonatal Surgery: A Method for Comparison of In-Hospital Mortality

OBJECTIVE: To develop a risk-adjustment method for evaluation of in-hospital mortality after noncardiac neonatal surgery regardless of gestational age. METHODS: Infants ≤ 30 days old undergoing noncardiac surgical procedures were identified by using the Kids' Inpatient Database (KID) 2000 + 2003. Neonates were included regardless of gestational age. International Classification of Disease, Ninth Revision, Clinical Modification codes were used to assign procedures to 1 of 4 previously derived risk categories. Prematurity and other clinical variables were assessed in logistic regression analysis. The final multivariable model was validated in 3 independent data sets: KID 2006, Pediatric Health Information System (PHIS) 2001-2003, and PHIS 2006-2008. The model was applied to generate standardized mortality ratios for institutions within PHIS 2006-2008. RESULTS: Among 18437 eligible cases in KID 2000 + 2003, 15278 (83%) had 1 of 66 procedure codes assigned to a risk category and were eligible for analysis. In-hospital mortality for premature infants was 10.5% compared with 2.0% for full-term neonates. In addition to risk category, the clinical variables improving prediction of in-hospital death were prematurity, serious respiratory conditions, necrotizing enterocolitis, neonatal sepsis, and congenital heart disease. Area under the receiver-operator characteristic curve for the final model was 0.90. The model also showed excellent discrimination in the 3 validation data sets (0.90, 0.89, and 0.89). Within 41 institutions in PHIS, standardized mortality ratios ranged from 0.37 to 1.91. CONCLUSIONS: This validated method provides a tool for risk adjustment of neonates undergoing noncardiac surgery to allow comparative analyses of in-hospital mortality.