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Rate of undesirable events at beginning of academic year: retrospective cohort study

BMJ 2009; 339 doi: (Published 14 October 2009) Cite this as: BMJ 2009;339:b3974
  1. Guy Haller, consultant14,
  2. Paul S Myles, professor and director2,
  3. Patrick Taffé, biostatistician3,
  4. Thomas V Perneger, professor and head of division4,
  5. Christopher L Wu, associate professor5
  1. 1Department of Anaesthesia, Pharmacology and Intensive Care, Geneva University Hospital, University of Geneva, 1211 Geneva, Switzerland
  2. 2Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Monash University, Prahran, Vic 3181, Australia
  3. 3Institute of Social and Preventive Medicine, 1005 Lausanne, Switzerland
  4. 4Division of Clinical Epidemiology, Geneva University Hospital
  5. 5Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore 21205, MD, USA
  1. Correspondence to: Guy Haller Guy.Haller{at}
  • Accepted 4 August 2009


Objective To determine whether an increase in the rate of undesirable events occurs after care provided by trainees at the beginning of the academic year.

Design Retrospective cohort study using administrative and patient record data.

Setting University affiliated hospital in Melbourne, Australia.

Participants 19 560 patients having an anaesthetic procedure carried out by first to fifth year trainees starting work for the first time at the hospital over a period of five years (1995-2000).

Main outcome measures Absolute event rates, absolute rate reduction, and rate ratios of undesirable events.

Results The rate of undesirable events was higher at the beginning of the academic year compared with the rest of the year (absolute event rate 137 v 107 per 1000 patient hours, relative rate reduction 28%, P<0.001). The overall adjusted rate ratio for undesirable events was 1.40, 95% confidence interval 1.24 to 1.58. This excess risk was seen for all residents, regardless of their level of seniority. The excess risk decreased progressively after the first month, and the trend disappeared fully after the fourth month of the year (rate ratio for fourth month 1.21, 0.93 to 1.57). The most important decreases were for central and peripheral nerve injuries (relative difference 82%), inadequate oxygenation of the patient (66%), vomiting/aspiration in theatre (53%), and technical failures of tracheal tube placement (49%).

Conclusions The rate of undesirable events was greater among trainees at the beginning of the academic year regardless of their level of clinical experience. This suggests that several additional factors, such as knowledge of the working environment, teamwork, and communication, may contribute to the increase.


  • Contributors: GH, PSM, and CLW were responsible for study conception and design. GH and PSM acquired the data. All authors analysed and interpreted the data. GH and CLW drafted the manuscript, and all authors revised it critically for important intellectual content. GH and PT did the statistical analysis. GH obtained funding. DH, PSM, TVP, and CLW provided administrative, technical, or material support. All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. GH and CLW are the guarantors.

  • Funding: This research was supported by a University of Geneva (Switzerland) postgraduate research scholarship awarded to GH. The sponsor had no role in study design; data collection, analysis, and interpretation; or publication of results. The researchers were all independent from the funder.

  • Competing interests: None declared.

  • Ethical approval: The study involved no contact with patients. The Alfred Institutional Ethics Committee approved the use of data retrieved from patients’ medical charts and hospital databases.

  • Data sharing: No additional data available.

  • Accepted 4 August 2009

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