title: A predictive rule for mortality of inpatients with Staphylococcus aureus bacteraemia: A classification and regression tree analysis.
abstract: OBJECTIVE
  To create a predictive rule to identify risk factors for mortality among patients with Staphylococcus aureus bacteraemia (SAB).
  
  
  METHODS
  This was a retrospective cohort study of all adult patients with SAB at a large community hospital in Tokyo, Japan, from April 1, 2004 to March 31, 2011. Baseline data and clinically relevant factors were collected from electronic charts. The primary outcome was in-hospital mortality. All candidate predictors were included in a classification and regression tree (CART) analysis. A receiver operating characteristic (ROC) curve was drawn, and the area under the curve (AUC) was obtained. A cross-validation analysis was performed.
  
  
  RESULTS
  A total of 340 patients had SAB during the study period. Of these, 118 (34.7%) patients died in hospital. Among 41 potential variables, the CART analysis revealed that underlying malignancy, serum blood glucose level, methicillin resistance, and low serum albumin were predictors of mortality. The AUC was 0.73 (95% CI: 0.67-0.79). For validation, the estimated risk was 0.26 (± SE: 0.02) in the resubstitution analysis and 0.33 (± SE: 0.03) in the cross-validation analysis.
  
  
  CONCLUSIONS
  We propose a predictive model for the mortality of patients with SAB consisting of four predictors: underlying malignancy, low serum albumin, high glucose, and methicillin resistance. This model may facilitate appropriate preventative management for patients with SAB who are at high risk of mortality.
authors.affiliation: Division of General Internal Medicine, Department of Medicine, St. Luke's International Hospital, Tokyo, Japan; Center for Clinical Epidemiology, St. Luke's Life Science Institute, Japan; Department of Infectious Disease, Faculty of Medicine, Kagawa University, Kagawa, Japan. Electronic address: daikoba@luke.ac.jp.
authors.forename: Daiki
authors.initials: D
authors.lastname: Kobayashi
authors.affiliation: Department of Infectious Disease, Faculty of Medicine, Kagawa University, Kita-gun, Japan. Electronic address: kyoyokota@hotmail.com.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Yokota
authors.affiliation: Division of General Internal Medicine, Department of Medicine, St. Luke's International Hospital, Tokyo, Japan; Center for Clinical Epidemiology, St. Luke's Life Science Institute, Japan. Electronic address: otakahas@luke.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Takahashi
authors.affiliation: Division of General Internal Medicine, Department of Medicine, St. Luke's International Hospital, Tokyo, Japan. Electronic address: arihiro@luke.ac.jp.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Arioka
authors.affiliation: Division of General Internal Medicine, Department of Medicine, St. Luke's International Hospital, Tokyo, Japan. Electronic address: fkts@luke.ac.jp.
authors.forename: Tsuguya
authors.initials: T
authors.lastname: Fukui
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D001786:Blood Glucose; D015331:Cohort Studies; D015897:Comorbidity; D003661:Decision Support Techniques; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007564:Japan; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology; D012372:ROC Curve; D012044:Regression Analysis; D012189:Retrospective Studies; D012709:Serum Albumin; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D013211:Staphylococcus aureus / Q000302:isolation & purification
chemical_list: D001786:Blood Glucose; D012709:Serum Albumin
keywords: Bacteraemia; CART analysis; Mortality; Predictive rule; Sepsis; Staphylococcus aureus