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• Statistical analysis of differences in turnover times among operating theatres
  Franklin Dexter
  Published on: 18 November 2016

• Published on: 18 November 2016

  Statistical analysis of differences in turnover times among operating theatres

  • Franklin Dexter, Professor

  Overdyk et al. used remote video auditing with real-time feedback in a surgical suite [1]. As part of their randomized trial clustered by theatre, they report less turnover times among "fast rooms," those generally including 3 or greater cases per day.

  Successive turnover times between scheduled cases within theatres on the same date tend to be correlated (e.g., caused by same surgeon, nurses, and anaesthetist)....

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  Overdyk et al. used remote video auditing with real-time feedback in a surgical suite [1]. As part of their randomized trial clustered by theatre, they report less turnover times among "fast rooms," those generally including 3 or greater cases per day.

  Successive turnover times between scheduled cases within theatres on the same date tend to be correlated (e.g., caused by same surgeon, nurses, and anaesthetist). This was shown in Dexter et al. 2005 and Austin et al. 2014 [2,3]. Overdyk et al.'s description of their statistical model seems not to describe consideration of correlations of turnover times within the same theatre on the same day. This can be rectified by including the theatre-day combination as a fixed or random effect. Alternatively, and typically, analyses take the simpler approach of batching (binning) by each day, week, 2 week, or 4-week period, and then comparing the periods (e.g., week) pairwise between control (i.e., no feedback) and intervention (i.e., feedback) theatres (e.g., Reference [3]). When the authors sort the turnover times in sequence of date, then theatre, and then start time, do the authors have statistically significant lag 1 correlation? If yes, then, when analyses are repeated by either including that correlation in the statistical model or by making comparison pairwise by week (or other suitable interval), what are the revised results of the authors' Table 2?

  Turnovers that are occurring simultaneously among theatres on the same day can be correlated if personnel are shared (e.g., housekeepers and anaesthesia technicians) [4,5]. For example, Wang et al. found most turnovers greater than 1 hour occurred at their studied surgical suite when there were >2 simultaneous turnovers [5]. Overdyk et al.'s description of their statistical model does not seem to describe consideration of correlations of turnover times on the same day and time among theatres. Although this can be rectified by including a fixed effect of the time varying number of simultaneous turnovers, usually analyses compensate by batching (binning) by each day, week, etc. [2-5]. Do the authors have significant correlation between numbers of simultaneous turnovers at each time and turnover times? If yes, then when analyses are repeated, what are the revised results of the authors' Table 2?

  References 1 Overdyk FJ, Dowling O, Newman S, et al. Remote video auditing with real- time feedback in an academic surgical suite improves safety and efficiency metrics: a cluster randomised study. BMJ Qual Saf 2015; PMID: 26658775 2 Dexter F, Epstein RH, Marcon E, et al. Estimating the incidence of prolonged turnover times and delays by time of day. Anesthesiology 2005;102:1242-8 3 Austin TM, Lam HV, Shin NS, et al. Elective change of surgeon during the OR day has an operationally negligible impact on turnover time. J Clin Anesth 2014;26:343-9 4 Dexter F, Marcon E, Aker J, et al. Numbers of simultaneous turnovers calculated from anesthesia or operating room information management system data. Anesth Analg 2009;109:900-5 5 Wang J, Dexter F, Yang K. A behavioral study of daily mean turnover times and first case of the day start tardiness. Anesth Analg 2013;116:1333-41

  Conflict of Interest:

  Financial disclosure: Arrowsight paid the University of Iowa's Department of Anesthesia for consulting by Dr. Dexter in 2012 (see http://www.FranklinDexter.net/FAQ.htm).

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  Conflict of Interest:
  None declared.

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