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Physician-level variation in clinical outcomes and resource use in inpatient general internal medicine: an observational study
  1. Amol A Verma1,2,3,4,
  2. Yishan Guo2,
  3. Hae Young Jung2,
  4. Andreas Laupacis1,2,3,
  5. Muhammad Mamdani1,2,3,
  6. Allan S Detsky1,4,5,6,
  7. Adina Weinerman1,7,
  8. Terence Tang1,8,
  9. Shail Rawal1,6,
  10. Lauren Lapointe-Shaw1,6,
  11. Janice L Kwan1,5,
  12. Fahad Razak1,2,3,4
  1. 1 Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  2. 2 Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada
  3. 3 Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada
  4. 4 Institute for Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada
  5. 5 Department of Medicine, Sinai Health System, Toronto, Ontario, Canada
  6. 6 Department of Medicine, University Health Network, Toronto, Ontario, Canada
  7. 7 Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  8. 8 Institute for Better Health, Trillium Health Partners, Mississauga, Ontario, Canada
  1. Correspondence to Dr Amol A Verma, LKS-CHART, St Michael's Hospital, Toronto, ON M5B 1W8, Canada; amol.verma{at}


Background Variations in inpatient medical care are typically attributed to system, hospital or patient factors. Little is known about variations at the physician level within hospitals. We described the physician-level variation in clinical outcomes and resource use in general internal medicine (GIM).

Methods This was an observational study of all emergency admissions to GIM at seven hospitals in Ontario, Canada, over a 5-year period between 2010 and 2015. Physician-level variations in inpatient mortality, hospital length of stay, 30-day readmission and use of ‘advanced imaging’ (CT, MRI or ultrasound scans) were measured. Physicians were categorised into quartiles within each hospital for each outcome and then quartiles were pooled across all hospitals (eg, physicians in the highest quartile at each hospital were grouped together). We report absolute differences between physicians in the highest and lowest quartiles after matching admissions based on propensity scores to account for patient-level variation.

Results The sample included 103 085 admissions to 135 attending physicians. After propensity score matching, the difference between physicians in the highest and lowest quartiles for in-hospital mortality was 2.4% (95% CI 0.6% to 4.3%, p<0.01); for readmission was 3.3% (95% CI 0.7% to 5.9%, p<0.01); for advanced imaging was 0.32 tests per admission (95% CI 0.12 to 0.52, p<0.01); and for hospital length of stay was 1.2 additional days per admission (95% CI 0.5 to 1.9, p<0.01). Physician-level differences in length of stay and imaging use were consistent across numerous sensitivity analyses and stable over time. Differences in mortality and readmission were consistent across most sensitivity analyses but were not stable over time and estimates were limited by sample size.

Conclusions Patient outcomes and resource use in inpatient medical care varied substantially across physicians in this study. Physician-level variations in length of stay and imaging use were unlikely to be explained by patient factors whereas differences in mortality and readmission should be interpreted with caution and could be explained by unmeasured confounders. Physician-level variations may represent practice differences that highlight quality improvement opportunities.

  • hospital medicine
  • health services research
  • quality improvement

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  • Twitter @AmolAVerma, @Adetsky, @FahadRazak

  • Correction notice The artice has been corrected since it was pusblished online first. The Funding and the Disclaimer statements have been updated.

  • Contributors The study was designed by AAV and FR with input from all coauthors. YG and HYJ performed statistical analysis. The manuscript was drafted by AAV and all coauthors provided critical revision for important intellectual content and input in writing. AAV, YG, HYJ, AW, TT, SR, LLS, JLK and FR were involved in collecting data.

  • Funding This study was funded by Green Shield Canada Foundation and University of Toronto Division of General Internal Medicine. FR is supported by an award from the Mak Pak Chiu and Mak-Soo Lai Hing Chair in General Internal Medicine, University of Toronto.

  • Disclaimer The funding agencies and Ontario Health had no role in the design, conduct or interpretation of this study, and the views expressed herein do not reflect the views of the organisations.

  • Competing interests AAV and FR are employees of Ontario Health.

  • Patient consent for publication Not required.

  • Ethics approval Research ethics board approval was obtained from all participating hospitals. A waiver of participant consent was obtained from research ethics boards of all participating hospitals.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request. The study’s lead investigators will make data for this manuscript available upon request as possible in compliance with local research ethics board requirements and data sharing agreements.