Patients who undergo surgery during the night may be twice more likely to die than those operated on during regular working hours, a new study has claimed.
Patients operated on later in the working day or in the early evening also have a higher mortality risk, according to researchers from McGill University in Canada.
A review of 30 day postoperative in hospital mortality was carried out in the Jewish General Hospital in Canada.
The study evaluated all surgical procedures for the past 5 years, starting from April 1, 2010 to March 31 last year.
A database was constructed collecting variables about surgical interventions.
All elective and emergent surgical cases were included except ophthalmic and local anaesthesia cases.
The working day was divided into three time blocks (daytime 7 AM-3:29 pm, evening 3:30-11:29 pm and night time 11:30 PM-7:29 am).
The start time of the anaesthetic recorded by the circulating nurse was used to determine in which time block the operation began.
There were 41,716 elective and emergency surgeries performed on 33,942 patients in 40,044 hospitalisations.
Of these, 10,480 were emergency procedures; there were 3,445; 4,951; and 2,084 emergency procedures with anaesthesia starting between day, evening and night respectively.
There were 226, 97 and 29 deaths of all cases during day, evening and night surgery (79, 95, 29 deaths for emergency surgery in the same time periods) respectively.
Researchers found that patients operated in the night were 2.17 times more likely to die than those operating on during regular daytime working hours.
The study also found that patients operated on in the late day were 1.43 times more likely to die than those operated on during regular daytime working hours.
“Postoperative 30-day in-hospital mortality rate should include start time of anaesthesia, along with other known variables, as a risk factor,” researchers said.
According to them, theoretical possible causes include, but are not limited to, provider fatigue during anaesthesia and surgery, overnight hospital staffing issues, delays in treatment (for example how many operating rooms are available), or the patient being too sick to be postponed prior to treatment.