Identified mortality risk factors associated with presentation, initial hospitalisation, and interstage period for the Norwood operation in a multi-centre registry: a report from the National Pediatric Cardiology-Quality Improvement Collaborative

Introduction: Despite improvements in care following Stage 1 palliation, interstage mortality remains substantial. The National Pediatric Cardiology-Quality Improvement Collaborative captures clinical process and outcome data on infants discharged into the interstage period after Stage 1. We sought to identify risk factors for interstage mortality using these data. Materials and methods: Patients who reached Stage 2 palliation or died in the interstage were included. The analysis was considered exploratory and hypothesis generating. Kaplan-Meier survival analysis was used to screen for univariate predictors, and Cox multiple regression modelling was used to identify potential independent risk factors. Results: Data on 247 patients who met the criteria between June, 2008 and June, 2011 were collected from 33 surgical centres. There were 23 interstage mortalities (9%). The identified independent risk factors of interstage mortality with associated relative risk were: hypoplastic left heart syndrome with aortic stenosis and mitral atresia (relative risk = 13), anti-seizure medications at discharge (relative risk = 12.5), earlier gestational age (relative risk = 11.1), nasogastric or nasojejunal feeding (relative risk = 5.5), unscheduled readmissions (relative risk = 5.3), hypoplastic left heart syndrome with aortic atresia and mitral stenosis (relative risk = 5.2), fewer clinic visits with primary cardiologist identified (relative risk = 3.1), and fewer post-operative vasoactive medications (relative risk = 2.2). Conclusion: Interstage mortality remains substantial, and there are multiple potential risk factors. Future efforts should focus on further exploration of each risk factor, with potential integration of the factors into surveillance schemes and clinical practice strategies.