External Validation of 3 Risk Scores in Adults with Congenital Heart Disease

BACKGROUND AND OBJECTIVES: Adults with congenital heart disease (CHD) are an increasing group of patients thanks to the survival of over 85% of children with CHD. 20% of these patients shall warrant a surgical procedure during their life span. However, currently there is no one risk score that assess correctly the mortality of these procedures. Thus, we analyse the risk scores used at our institution. METHODS: From May 1991 till June 2017, 608 procedures in adults with CHD were performed. The 3 risk scores (risk adjustment for congenital heart surgery [RACHS-1], Aristotle, and Euroscore I) of each procedure were analysed. We used area under the receiver operating characteristic curve (c-index) to measure model discrimination, and Hosmer-Lemeshow (H-L) statistic along with calibration plots to measure calibration. RESULTS: There was no statistical difference between the area under the curve for the 3 scores (χ²=0.58 with 2 df, p=0.750). There was no evidence of lack of fit for RACHS-1 (H-L, χ²=2.61; p=0.271) and Aristotle score (H-L, χ²=5.69; p=0.459). However, there was evidence in lack of calibration in the Euroscore I scoring system (H-L, χ²=33.69; p<0.001). The calibration slope for RACHS-1 was 0.912, for Aristotle (stratified in risk groups) was -0.14 and for Euroscore 1 (stratified in risk groups) was 0.46. CONCLUSIONS: RACHS-1 seems to be best risk scoring system for calculating mortality applied to surgery in adults with CHD.