Improving Risk Adjustment for Mortality After Pediatric Cardiac Surgery: The UK PRAiS2 Model.
BACKGROUND
Partial Risk Adjustment in Surgery (PRAiS), a risk model for 30-day mortality after children's heart surgery, has been used by the UK National Congenital Heart Disease Audit to report expected risk-adjusted survival since 2013. This study aimed to improve the model by incorporating additional comorbidity and diagnostic information.


METHODS
The model development dataset was all procedures performed between 2009 and 2014 in all UK and Ireland congenital cardiac centers. The outcome measure was death within each 30-day surgical episode. Model development followed an iterative process of clinical discussion and development and assessment of models using logistic regression under 25 × 5 cross-validation. Performance was measured using Akaike information criterion, the area under the receiver-operating characteristic curve (AUC), and calibration. The final model was assessed in an external 2014 to 2015 validation dataset.


RESULTS
The development dataset comprised 21,838 30-day surgical episodes, with 539 deaths (mortality, 2.5%). The validation dataset comprised 4,207 episodes, with 97 deaths (mortality, 2.3%). The updated risk model included 15 procedural, 11 diagnostic, and 4 comorbidity groupings, and nonlinear functions of age and weight. Performance under cross-validation was: median AUC of 0.83 (range, 0.82 to 0.83), median calibration slope and intercept of 0.92 (range, 0.64 to 1.25) and -0.23 (range, -1.08 to 0.85) respectively. In the validation dataset, the AUC was 0.86 (95% confidence interval [CI], 0.82 to 0.89), and the calibration slope and intercept were 1.01 (95% CI, 0.83 to 1.18) and 0.11 (95% CI, -0.45 to 0.67), respectively, showing excellent performance.


CONCLUSIONS
A more sophisticated PRAiS2 risk model for UK use was developed with additional comorbidity and diagnostic information, alongside age and weight as nonlinear variables.
Clinical Operational Research Unit, University College London, London, United Kingdom. Electronic address: libby.rogers@ucl.ac.uk.
Libby
L
Rogers
Cardiac, Critical Care and Respiratory Division, Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom.
Katherine L
KL
Brown
Pediatric Cardiology, Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom.
Rodney C
RC
Franklin
Department of Statistical Science, University College London, London, United Kingdom.
Gareth
G
Ambler
Cardiology and Critical Care, Evelina London Children's Hospital, London, United Kingdom.
David
D
Anderson
Cardiothoracic Surgery, Birmingham Children's Hospital, Birmingham, United Kingdom.
David J
DJ
Barron
Clinical Operational Research Unit, University College London, London, United Kingdom.
Sonya
S
Crowe
Department of Congenital Cardiology, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom.
Kate
K
English
Cardiothoracic Surgery, Birmingham Children's Hospital, Birmingham, United Kingdom.
John
J
Stickley
Cardiology and Critical Care, Evelina London Children's Hospital, London, United Kingdom.
Shane
S
Tibby
Cardiac, Critical Care and Respiratory Division, Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom.
Victor
V
Tsang
Clinical Operational Research Unit, University College London, London, United Kingdom.
Martin
M
Utley
Cardiology and Critical Care, Evelina London Children's Hospital, London, United Kingdom.
Thomas
T
Witter
Clinical Operational Research Unit, University College London, London, United Kingdom.
Christina
C
Pagel
D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000401:mortality / Q000601:surgery*; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D015994:Incidence; D007494:Ireland / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology*; D012372:ROC Curve; D012189:Retrospective Studies; D020379:Risk Adjustment / Q000639:trends*; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D006113:United Kingdom / Q000453:epidemiology