EXTERNAL VALIDATION OF THE IMPROVING PARTIAL RISK ADJUSTMENT IN SURGERY (PRAIS2) MODEL FOR 30-DAY MORTALITY AFTER PEDIATRIC CARDIAC SURGERY

Objective: Risk stratification in paediatric patients undergoing heart surgery remains a challenge. The improving partial risk adjustment in surgery (PRAIS2) is a risk model predicting 30-day mortality which has been recently developed and validated using a UK-based cohort from April 2009-March 2015. We aimed to perform an independent temporal external validation to explore its generalisability and clinical utility. Methods: PRAIS2 validation was carried out using a single centre (Bristol, UK) cohort from April 2004 to March 2009 and April 2015 to July 2019. For each subject PRAIS2 score was calculated according to the original formula. PRAIS2 performance was assessed in terms of discrimination by means of ROC curve analysis and calibration by using the calibration belt method. Results: A total of 1330 (2004-2009) and 1187 (2015-2019) paediatric cardiac surgical procedures were included in the first and second independent validation, respectively (median age at the procedure 6.0 and 6.9 months). PRAIS2 score showed excellent discrimination for both independent validations (AUC 0.72 (95%CI: 0.65 to 0.80) and 0.87 (95%CI: 0.82 to 0.93), respectively). While PRAIS2 was only marginally calibrated in the first validation, with a tendency to underestimate risk P-value = 0.051), the second validation showed good calibration with 95% confidence belt containing the bisector for predicted mortality (P-value = 0.15); We also observed good performance in the subgroup of patients undergoing non-elective procedures (N = 482; AUC 0.78 (95%CI 0.68 to 0.87); Calibration belt containing the bisector (P-value=0.61). Conclusions: In a single centre UK-based cohort, PRAIS2 showed excellent discrimination and calibration in predicting 30-day mortality in paediatric cardiac surgery including in those undergoing non-elective procedures. Our results support a wider adoption of PRAIS2 score in the clinical practice.