title: Applicability of Ambler's risk score to patients who have undergone valve replacement with bovine pericardial bioprosthesis.
abstract: OBJECTIVE
  This study aims to verify the applicability of Ambler's risk score to patients who have undergone implantation of bovine pericardial bioprosthesis at the Instituto de Cardiologia do RGS/FCU. This study also aims to quantify the risk factors.
  
  
  METHODS
  Retrospective study with 703 patients who had undergone implantation of bovine pericardial bioprosthesis between 1991 and 2005 at the Instituto de Cardiologia do RS. Aortic implant occurred in 392 patients, mitral in 250 and combined in 61. Primary outcome was hospital mortality. Characteristics used to estimate risk were: gender, age, body mass index (BMI), NYHA functional class, left ventricular ejection fraction, valvular lesions, systemic arterial hypertension, diabetes mellitus, renal function, cardiac rhythm, previous cardiac operations, and surgical priority. Univariate and multivariate logistic regression was used to quantify preponderant risk factors by the odds-ratio (OR).
  
  
  RESULTS
  The mortality rate was 14.3%, which was higher than the estimated mortality rate (3%, according to Ambler's mean score of 6, (p<0.01)). Patients who died presented a mean score of 8.26, which was higher than the survivors' average score of 5.68. Characteristics of increased risk were emergency surgery (OR=10.87), dialysis (OR=6.10), and age higher than 80 years (OR=6.10). Our sample indicates an area under the ROC curve of 72.9% (accepted value > 70%).
  
  
  CONCLUSIONS
  The mortality predicted in Ambler's score was not reproduced in the observed results. However, the ROC curve provides evidence that this model is applicable. Preponderant risk factors were individualizated.
authors.affiliation: FFFCMPA, Bolsista de Iniciação Científica do IC/FUC-FAPERGS, Porto Alegre, RS, Brasil.
authors.forename: Gustavo de
authors.initials: Gd
authors.lastname: Bacco
authors.forename: Mateus W de
authors.initials: MW
authors.lastname: Bacco
authors.forename: João Ricardo Michelin
authors.initials: JR
authors.lastname: Sant'Anna
authors.forename: Marisa F
authors.initials: MF
authors.lastname: Santos
authors.forename: Roberto T
authors.initials: RT
authors.lastname: Sant'Anna
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Prates
authors.forename: Renato A K
authors.initials: RA
authors.lastname: Kalil
authors.forename: Ivo A
authors.initials: IA
authors.lastname: Nesralla
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001022:Aortic Valve Insufficiency / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D001705:Bioprosthesis; D001938:Brazil / Q000453:epidemiology; D002417:Cattle; D003956:Dialysis / Q000009:adverse effects; D004638:Emergency Treatment / Q000009:adverse effects; D004812:Epidemiologic Methods; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010496:Pericardium; D012016:Reference Values; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult