Predictive value of paediatric risk of mortality score and risk adjustment for congenital heart surgery score after paediatric open-heart surgery

This study compared the performance of risk adjustment for congenital heart surgery (RACHS-1) score with paediatric risk of mortality (PRISM) score in operative risk prediction after open-heart surgery in children. This was a retrospective analysis of a non-selected patient population from the paediatric intensive care unit of Helsinki University Hospital. All consecutive congenital open-heart surgery patients operated in Finland between the years 2000 and 2004, who were under 18 years of age, were included in this retrospective analysis. Predicted probability of mortality was calculated using the published algorithms for RACHS-1 and PRISM. Those were compared with observed mortality at day 30 postoperatively. Of the 1001 patients, 42 patients died (4.2%) within 30 days of open-heart surgery. The discrimination power, evaluated by AUC (area under curve) for RACHS-1 was moderate: 0.74 (95% CI 0.66-0.82). The AUC-value for PRISM was poor, namely 0.66 (95% CI 0.57-0.75). Both risk scoring systems overestimated the mortality with calculated standardised mortality ratios (SMR) of 0.48 for PRISM and 0.39 for RACHS-1. With only a moderate discriminating AUC, RACHS-1 failed to adequately predict death after paediatric open-heart surgery. The predictive power of PRISM in this patient group was poor. Both scores overestimated the actual mortality rate.