Comparison of four contemporary risk models at predicting mortality after aortic valve replacement.
OBJECTIVE
Risk stratification for aortic valve replacement (AVR) is desirable given the increased demand for intervention and the introduction of transcatheter aortic valve implantation. We compared the prognostic utility of the European System for Cardiac Operative Risk Evaluation (EuroSCORE), EuroSCORE II, Society of Thoracic Surgeons (STS) score, and an Australasian model (Aus-AVR score) for AVR.


METHODS
We retrospectively calculated the 4 risk scores for patients undergoing isolated AVR at Auckland City Hospital from 2005 to 2012 and assessed their discrimination and calibration for short- and long-term mortality.


RESULTS
A total of 620 patients were followed up for 3.8 ± 2.4 years, with an operative mortality of 2.9% (n = 18). The mean EuroSCORE, EuroSCORE II, STS score, and Aus-AVR score was 8.7% ± 8.3%, 3.8% ± 4.7%, 2.8% ± 2.7%, and 3.2% ± 4.8%, respectively. The corresponding C-statistics for operative mortality were 0.752 (95% confidence interval [CI], 0.652-0.852), 0.711 (95% CI, 0.607-0.815), 0.716 (95% CI, 0.593-0.837), and 0.684 (95% CI, 0.557-0.811). The corresponding Hosmer-Lemeshow test P and chi-square values for calibration were .007 and 21.1, .125 and 12.6, .753 and 5.0, and .468 and 7.7. The corresponding Brier scores were 0.0348, 0.0278, 0.0276, and 0.0294. Independent predictors of operative mortality included critical preoperative state, atrial fibrillation, extracardiac arteriopathy, and mitral stenosis. The log-rank test P values were all <.001 for mortality during follow-up for all 4 scores, stratified by quintile.


CONCLUSIONS
All 4 risk scores discriminated operative mortality after isolated AVR. The EuroSCORE had poor calibration, overestimating operative mortality, although the other 3 scores fitted well with contemporary outcomes. The STS score was the best calibrated in the highest quintile of operative risk.
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand. Electronic address: TWang@adhb.govt.nz.
Tom Kai Ming
TK
Wang
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand.
David H M
DH
Choi
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand; Department of Medicine, University of Auckland, Auckland, New Zealand.
Ralph
R
Stewart
Department of Medicine, University of Auckland, Auckland, New Zealand.
Greg
G
Gamble
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand.
David
D
Haydock
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand; Department of Medicine, University of Auckland, Auckland, New Zealand.
Peter
P
Ruygrok
D000368:Aged; D001022:Aortic Valve Insufficiency / Q000401:mortality / Q000601:surgery*; D001024:Aortic Valve Stenosis / Q000401:mortality / Q000601:surgery*; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods* / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome