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Research shows no increased risk of death associated with overnight emergency surgery
A study conducted at the Jewish General Hospital (JGH) in Montreal concluded that patients who undergo emergency surgery during the overnight hours are at no greater risk of mortality than those who are operated upon during the day. Preliminary results of these findings had been presented at the World Congress of Anaesthesiologists in Hong Kong and the American Society of Anesthesiologists in Chicago in 2016, and have now been published in Anaesthesia.

“Previous studies had detected an association between when surgeries began and mortality in non-emergency surgeries, but we questioned their methodology,” said the paper’s lead author, Dr. Michael Tessler, an anesthesiologist at the JGH and Associate Professor of Anesthesia at McGill University.

Within the medical community, there has long been a debate as to whether patients who undergo surgery during the overnight hours are at greater risk than those who are operated upon during the day.

Dr. Tessler and his co-authors assessed more than 10,400 emergency surgeries performed on more than 9,300 patients at the JGH over five years (2010-2015). They focused on emergency surgeries because those could not, by their very nature, be planned and needed to be performed whenever the cases presented. Thus, there was no element of choice in regard to the time of day at which they were performed. The inquiry found no statistically significant connection between time of surgery, nor whether the emergency occurred on a weekday or the weekend, and mortality. Rather, mortality was associated with the patient’s age, physical status, and urgency of surgery. Among the patients for whom there was complete data, 2.3% died within thirty days of emergency surgery.

“Fatigue is recognized as a factor in performance in a number of disciplines, so it seemed important to investigate whether mortality statistics indicated that it was a factor in overnight surgery. Moreover, there is also the question of whether surgery at night might be affected by reduced on-site resources as compared with the day shifts,” Dr. Tessler said. “We looked exclusively at emergency procedures because, at the Jewish General Hospital, we don’t do elective surgery off-hours, so it was an opportunity to compare only those operations which must be performed whenever they occur, meaning that we were comparing procedures with similar risk profiles. Overall, there is a higher incidence of negative outcomes in emergency surgery than elective.”

Surgeons working overnight or on call are accustomed to keeping alert and responding to situations when they arise. Thus, it isn’t necessarily surprising that mortality rates are unaffected by time of surgery. Nonetheless, given the intuitive idea that shift workers experience disruptions to their normal sleep rhythms, it is reassuring to have evidence supporting the readiness of physicians and other essential personnel to perform the most complex and stressful tasks whenever the demand arises.

The association of time of emergency surgery – day, evening or night – with postoperative 30‐day hospital mortality, M. J. Tessler, L. Charland, N. N. Wang, J. A. Correa, Anaesthesia
Presented in part at the World Congress of Anaesthesiologists, Hong Kong, September 2016, and the American Society of Anesthesiologists, Chicago, October 2016.

For media inquiries, and to arrange interviews with Dr. Tessler contact:

Tod Hoffman
Research Communications Officer
Lady Davis Institute
Tel: 514-340-8222 x 28661

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