The risk of death following surgery is the highest on weekends, in the afternoons and the month of February, a new German study has claimed.
Hospital mortality is subject to day-night, weekly and seasonal variability. However, a cyclic influence on hospital mortality has not been shown in patients after surgery.
The research by Dr Felix Kork and Professor Claudia Spies, from the University Medicine Berlin, Germany and colleagues, investigated the daily, weekly, and seasonal variability of hospital mortality in patients after surgery.
Hospital mortality is subject to day-night, weekly and seasonal variability. This has been shown for various populations, settings, and in different regions of the world.
A retrospective analysis was carried out on patients who underwent surgery between 2006 and 2011 at the two University Hospital Campuses of Charite Tertiary Care University Centre, Berlin. Data was then modelled to work out cyclical patterns.
In this first analysis of the data, a total of 218,758 patients were included. Hospital mortality showed variability over the course of the day, during different weekdays, and different months.
Surgery conducted in the afternoon was associated with 21 per cent increased risk of death compared with surgery conducted at other times of day.
Surgery at the weekend was associated with a 22 per cent increased risk of death compared with surgery on weekdays.
February was the highest risk month for surgery, with surgery in February associated with a 16 per cent increased risk of death compared with surgery in all other months.
Further work on the data will be carried out in the coming months, including looking at the possible reasons behind the variations, researchers said.
"Several factors may have influenced this outcome. For example, it may be that standard of care differs throughout the day and between weekdays and weekends.
"Although we controlled for risk factors including emergency surgery in our study, it may very well be that the patients treated in the afternoon and on the weekends were more severely ill. We need more data to draw conclusions regarding seasonal variation in postoperative outcome," the researchers said.
