Night Time Surgery 'Doubles Death Risk'

Peter Russell

August 30, 2016

People who undergo surgery at night are twice as likely to die as those operated on during regular daytime hours, research suggests.

The findings, being presented at a conference, also suggest a higher than usual risk of death among those who have surgery later in the day and in the early evening.

30-Day Hospital Survival Rates

The results are based on studying 30-day survival rates for patients at a hospital in Montreal, Canada. Between April 2010 and March 2015, the researchers were able to compile a database of 41,716 emergency and routine operations carried out on 33,942 patients.

The operations were classified as taking place either in the daytime between 7.30 am and 3.29 pm; during the evening between 3.30 pm and 11.29 pm; or at night between 11.30 pm and 7.29 am.

The researchers found that, after making allowances for assessment of patients' overall health and other factors such as age, those patients operated on in the night were 2.17 times more likely to die than those operated on during regular daytime working hours. Also, patients operated on late in the day were 1.43 times more likely to die than those operated on during regular daytime working hours.

Doctor Fatigue and Staff Shortages

The researchers say there may be a number of reasons for why night time surgery is more risky. These include fatigue among medical staff, overnight staffing shortages or treatment delays. They write: "Analysis of each of these possibilities is important to understand the reasons for this increased mortality and to direct any remedial action in an effort to reduce postoperative mortality."

These preliminary findings are being presented at this year's World Congress of Anaesthesiologists in Hong Kong. The results should be treated with caution as they have yet to be published in a peer-reviewed journal.


Retrospective analysis of time of day of surgery and its 30 day in-hospital postoperative mortality rate at a single Canadian institution, N Wang et al, Poster presentation 601, World Congress of Anaesthesiologists

Press release, Department of Anesthesia, McGill University Health Centre, Montreal


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