title: Outcomes and processes of care related to preoperative medical consultation.
abstract: BACKGROUND
  Preoperative consultations by internal medicine physicians facilitate documentation of comorbid disease, optimization of medical conditions, risk stratification, and initiation of interventions intended to reduce risk. Nonetheless, the impact of these consultations, which may be performed by general internists or specialists, on outcomes is unclear.
  
  
  METHODS
  We used population-based administrative databases to conduct a cohort study of patients 40 years or older who underwent major elective noncardiac surgery in Ontario, Canada, between 1994 and 2004. Propensity scores were used to assemble a matched-pairs cohort that reduced differences between patients who did and did not undergo preoperative consultation by general internists or specialists. The association of consultation with mortality and hospital stay was determined within this matched cohort. As a sensitivity analysis, we evaluated the association of consultation with an outcome for which no difference would be expected: postoperative wound infection.
  
  
  RESULTS
  Of 269,866 patients in the cohort, 38.8% (n=104,695) underwent consultation. Within the matched cohort (n=191,852), consultation was associated with increased 30-day mortality (relative risk [RR], 1.16; 95% confidence interval [CI], 1.07-1.25; number needed to harm, 516), 1-year mortality (1.08; 1.04-1.12; number needed to harm, 227), mean hospital stay (difference, 0.67 days; 0.59-0.76), preoperative testing, and preoperative pharmacologic interventions. Notably, consultation was not associated with any difference in postoperative wound infections (RR, 0.98; 95% CI, 0.95-1.02). These findings were stable across subgroups as well as sensitivity analyses that tested for unmeasured confounding.
  
  
  CONCLUSIONS
  Medical consultation before major elective noncardiac surgery is associated with increased mortality and hospital stay, as well as increases in preoperative pharmacologic interventions and testing. These findings highlight the need to better understand mechanisms by which consultation influences outcomes and to identify efficacious interventions to decrease perioperative risk.
authors.affiliation: Institute for Clinical Evaluative Sciences, Keenan Research Centre, Li Ka Shing Knowledge Institute of St Michael's Hospital, Department of Anesthesia, Toronto General Hospital and University of Toronto, EN 3-450, 200 Elizabeth St, Toronto, ON M5G 2C4, Canada. d.wijeysundera@utoronto.ca
authors.forename: Duminda N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
authors.forename: Janet E
authors.initials: JE
authors.lastname: Hux
authors.forename: Andreas
authors.initials: A
authors.lastname: Laupacis
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002908:Chronic Disease; D015897:Comorbidity; D016001:Confidence Intervals; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D007388:Internal Medicine; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D009864:Ontario / Q000453:epidemiology; D010043:Outcome and Process Assessment, Health Care; D011300:Preoperative Care / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013514:Surgical Procedures, Operative / Q000401:mortality*