title: Comparison of Risk Scores for Prediction of Complications following Aortic Valve Replacement.
abstract: BACKGROUND
  Risk models play an important role in stratification of patients for cardiac surgery, but their prognostic utilities for post-operative complications are rarely studied. We compared the EuroSCORE, EuroSCORE II, Society of Thoracic Surgeon's (STS) Score and an Australasian model (Aus-AVR Score) for predicting morbidities after aortic valve replacement (AVR), and also evaluated seven STS complications models in this context.
  
  
  METHODS
  We retrospectively calculated risk scores for 620 consecutive patients undergoing isolated AVR at Auckland City Hospital during 2005-2012, assessing their discrimination and calibration for post-operative complications.
  
  
  RESULTS
  Amongst mortality scores, the EuroSCORE was the best at discriminating stroke (c-statistic 0.845); the EuroSCORE II at deep sternal wound infection (c=0.748); and the STS Score at composite morbidity or mortality (c=0.666), renal failure (c=0.634), ventilation>24 hours (c=0.732), return to theatre (c=0.577) and prolonged hospital stay >14 days post-operatively (c=0.707). The individual STS complications models had a marginally higher c-statistic (c=0.634-0.846) for all complications except mediastinitis, and had good calibration (Hosmer-Lemeshow test P-value 0.123-0.915) for all complications.
  
  
  CONCLUSIONS
  The STS Score was best overall at discriminating post-operative complications and their composite for AVR. All STS complications models except for deep sternal wound infection had good discrimination and calibration for post-operative complications.
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand. Electronic address: TWang@adhb.govt.nz.
authors.forename: Tom Kai Ming
authors.initials: TK
authors.lastname: Wang
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand.
authors.forename: David Hyun-Min
authors.initials: DH
authors.lastname: Choi
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Haydock
authors.affiliation: Department of Medicine, University of Auckland, Auckland, New Zealand.
authors.forename: Greg
authors.initials: G
authors.lastname: Gamble
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand; Department of Medicine, University of Auckland, Auckland, New Zealand.
authors.forename: Ralph
authors.initials: R
authors.lastname: Stewart
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand; Department of Medicine, University of Auckland, Auckland, New Zealand.
authors.forename: Peter
authors.initials: P
authors.lastname: Ruygrok
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000401:mortality* / Q000601:surgery*; D015331:Cohort Studies; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods* / Q000401:mortality; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D011183:Postoperative Complications / Q000401:mortality / Q000503:physiopathology; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D015996:Survival Rate; D016896:Treatment Outcome
keywords: Aortic stenosis; Aortic valve replacement; Cardiac surgery complications; Risk score; Valve surgery