Intended for healthcare professionals

CCBYNC Open access

Comparison of postoperative outcomes among patients treated by male and female surgeons: a population based matched cohort study

BMJ 2017; 359 doi: (Published 10 October 2017) Cite this as: BMJ 2017;359:j4366
  1. Christopher JD Wallis, resident12,
  2. Bheeshma Ravi, surgeon and assistant professor3,
  3. Natalie Coburn, surgeon and, associate professor4,
  4. Robert K Nam, surgeon and professor1,
  5. Allan S Detsky, internist and professor25,
  6. Raj Satkunasivam, surgeon and assistant professor16
  1. 1Division of Urology, Sunnybrook Health Sciences Centre, University of Toronto, ON M4N 3M5, Canada
  2. 2Institute of Health Policy, Management, and Evaluation, University of Toronto
  3. 3Division of Orthopedic Surgery, Sunnybrook Health Sciences Centre
  4. 4Division of General Surgery, Sunnybrook Health Sciences Centre
  5. 5Department of Medicine, Mount Sinai Hospital, University Health Network, University of Toronto
  6. 6Department of Urology and Center for Outcomes Research, Houston Methodist Hospital, Houston, TX, USA.
  1. Correspondence to: R Satkunasivam at raj.satkunasivam{at}
  • Accepted 13 September 2017


Objective To examine the effect of surgeon sex on postoperative outcomes of patients undergoing common surgical procedures.

Design Population based, retrospective, matched cohort study from 2007 to 2015.

Setting Population based cohort of all patients treated in Ontario, Canada.

Participants Patients undergoing one of 25 surgical procedures performed by a female surgeon were matched by patient age, patient sex, comorbidity, surgeon volume, surgeon age, and hospital to patients undergoing the same operation by a male surgeon.

Interventions Sex of treating surgeon.

Main outcome measure The primary outcome was a composite of death, readmission, and complications. We compared outcomes between groups using generalised estimating equations.

Results 104 630 patients were treated by 3314 surgeons, 774 female and 2540 male. Before matching, patients treated by female doctors were more likely to be female and younger but had similar comorbidity, income, rurality, and year of surgery. After matching, the groups were comparable. Fewer patients treated by female surgeons died, were readmitted to hospital, or had complications within 30 days (5810 of 52 315, 11.1%, 95% confidence interval 10.9% to 11.4%) than those treated by male surgeons (6046 of 52 315, 11.6%, 11.3% to 11.8%; adjusted odds ratio 0.96, 0.92 to 0.99, P=0.02). Patients treated by female surgeons were less likely to die within 30 days (adjusted odds ratio 0.88; 0.79 to 0.99, P=0.04), but there was no significant difference in readmissions or complications. Stratified analyses by patient, physician, and hospital characteristics did not significant modify the effect of surgeon sex on outcome. A retrospective analysis showed no difference in outcomes by surgeon sex in patients who had emergency surgery, where patients do not usually choose their surgeon.

Conclusions After accounting for patient, surgeon, and hospital characteristics, patients treated by female surgeons had a small but statistically significant decrease in 30 day mortality and similar surgical outcomes (length of stay, complications, and readmission), compared with those treated by male surgeons. These findings support the need for further examination of the surgical outcomes and mechanisms related to physicians and the underlying processes and patterns of care to improve mortality, complications, and readmissions for all patients.


  • We thank Refik Saskin and Lisa Ellison for their methodological and analytical support.

  • Contributors and sources: CJDW and RS conceived the study and were responsible for the design and development of the data analysis. CJDW, BR, ASD and RS were responsible for data assembly, collection, and analysis. CJDW, BR, NC, RKN, ASD, and RS were responsible for data interpretation. CJDW wrote the first draft. All authors provided significant revisions for important intellectual content and approved the final version. CJDW and RS affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

  • Funding: This study received no support from any organisation. CJDW is supported by the Canadian Institute of Health Research Banting and Best Doctoral Award. NGC is supported by the Sherif and MaryLou Hanna Chair in Surgical Oncology. RKN is supported by the Ajmera Family Chair in Urologic Oncology.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Data sharing: Statistical code is available from the RS ( Given the administrative nature of the data, patients did not give informed consent for data sharing but all data are fully anonymised, and risk of identification is low.

  • Disclaimer: This study made use of de-identified data from the ICES Data Repository, which is managed by the Institute for Clinical Evaluative Sciences with support from its funders and partners: Canada’s Strategy for Patient-Oriented Research (SPOR), the Ontario SPOR Support Unit, the Canadian Institutes of Health Research and the Government of Ontario. The opinions, results and conclusions reported are those of the authors. No endorsement by ICES of any of its funders or partners is intended or should be inferred.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

View Full Text