title: Mortality in low- and very low-risk patients undergoing cardiac surgery: evaluation according to the EuroSCORE II as a new standard.
abstract: BACKGROUND
  Only a few reports have analyzed low-risk patient outcomes and in every case, the risk was based on a logistic EuroSCORE ≤ 2. Since this original EuroSCORE overestimates surgical risk, we developed this study to prospectively evaluate the immediate results of cardiac surgery in patients with an expected mortality risk ≤ 2% according to the EuroSCORE II as a new gold standard. We also examined the cause of death and whether it could be considered preventable.
  
  
  METHODS
  A prospective risk stratification of all cardiac surgical patients treated at the Bue-nos Aires University Hospital of Argentina was performed between 2012 and 2014 using the EuroSCORE II. Causes of death were classified as preventable or not preventable.
  
  
  RESULTS
  From a total of 990 patients, 63.2% had EuroSCORE II ≤ 2 (low-risk group) and 32.5% EuroSCORE II < 1 (very low-risk group). In the low-risk group, in-hospital mortal-ity was 1.8%, whereas predicted mortality was 1.04% (AUC 0.765). The observed/expected ratio was 1.73 (95% CI 0.68-4.43) and the observed-expected difference was 0.76 (95% CI -0.68-2.10). Fifty-four percent of deaths were considered preventable.
  
  
  CONCLUSIONS
  We propose to use and further validate the EuroSCORE II as a new standard for assessing low-risk patients. This model proved to be useful in evaluating the quality standards of local cardiac surgery. The review of cause of death in low-risk patients provided valuable information, which revealed potentially correctable issues. Adoption of a more demanding standard, as the EuroSCORE II to identify low-risk patients, avoids the sense of safety offered by previous versions of the score.
authors.affiliation: School of Medicine, Austral University, Buenos Aires, Argentina Hospital de Clínicas "José de San Martín", School of Medicine, Buenos Aires University, Argentina. raborracci@gmail.com.
authors.forename: Raul Alfredo
authors.initials: RA
authors.lastname: Borracci
authors.forename: Miguel
authors.initials: M
authors.lastname: Rubio
authors.forename: Julio
authors.initials: J
authors.lastname: Baldi
authors.forename: Rodolfo A
authors.initials: RA
authors.lastname: Ahuad Guerrero
authors.forename: Víctor
authors.initials: V
authors.lastname: Mauro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001118:Argentina / Q000453:epidemiology; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000401:mortality* / Q000592:standards; D002423:Cause of Death; D016009:Chi-Square Distribution; D003661:Decision Support Techniques; D005260:Female; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality* / Q000517:prevention & control; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019984:Quality Indicators, Health Care; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: EuroSCORE II; perioperative care; risk analysis; surgical complications