title: Association between day of the week of elective surgery and postoperative mortality.
abstract: BACKGROUND
  In prior studies, higher mortality was observed among patients who had elective surgery on a Friday rather than earlier in the week. We investigated whether mortality after elective surgery was associated with day of the week of surgery in a Canadian population and whether the association was influenced by surgeon experience and volume.
  
  
  METHODS
  We conducted a population-based retrospective cohort study in the province of Ontario, Canada. We included adults who underwent 1 of 12 elective daytime surgical procedures from Apr. 1, 2002, to Dec. 31, 2012. The primary outcome was 30-day mortality. We used generalized estimating equations to compare outcomes for surgeries performed on different days of the week, adjusting for patient and surgeon factors.
  
  
  RESULTS
  A total of 402 899 procedures performed by 1691 surgeons met our inclusion criteria. The median length of hospital stay was 6 (interquartile range 5-8) days. Surgeon experience varied significantly by day of week (p< 0.001), with surgeons operating on Fridays having the least experience. Nearly all of the patients who had their procedure on a Friday had postoperative care on the weekend, as compared with 49.1% of those whose surgery was on a Monday (p< 0.001). We found no difference in the 30-day mortality between procedures performed on Fridays and those performed on Mondays (adjusted odds ratio 1.08, 95% confidence interval 0.97-1.21).
  
  
  CONCLUSIONS
  Although surgeon experience differed across days of the week, the risk of 30-day mortality after elective surgery was similar regardless of which day of the week the procedure took place.
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont. Luc.Dubois@lhsc.on.ca.
authors.forename: Luc
authors.initials: L
authors.lastname: Dubois
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Kelly
authors.initials: K
authors.lastname: Vogt
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Chris
authors.initials: C
authors.lastname: Vinden
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Winick-Ng
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: J Andrew
authors.initials: JA
authors.lastname: McClure
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Pavel S
authors.initials: PS
authors.lastname: Roshanov
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Chaim M
authors.initials: CM
authors.lastname: Bell
authors.affiliation: Departments of Surgery (Dubois, Vogt, Vinden) and of Epidemiology and Biostatistics (Dubois, Vogt, Garg), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Institute for Clinical Evaluative Sciences (Vinden, Winick-Ng, McClure, Bell, Garg), Toronto, Ont.; Lilibeth Caberto Kidney Clinical Research Unit (Roshanov), London Health Sciences Centre, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Roshanov), McMaster University, Hamilton, Ont.; Department of Medicine (Bell), Mount Sinai Hospital, University of Toronto, Ont.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
mesh_terms: D000368:Aged; D001071:Appointments and Schedules; D002170:Canada; D015331:Cohort Studies; D017558:Elective Surgical Procedures / Q000401:mortality*; D005260:Female; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D009864:Ontario; D011182:Postoperative Care; D012189:Retrospective Studies; D012306:Risk; D066231:Surgeons / Q000706:statistics & numerical data*; D013514:Surgical Procedures, Operative / Q000401:mortality; D013997:Time Factors