Everyone who needs an operation (which eventually will include most of us) wants to be assured that it will be carried out in the best and safest conditions possible. All operations are serious for those having them; a minor operation, as the British physician George Pickering once put it, is an operation carried out on someone else.

Most people with the time or ability to search for the best hospitals, surgeons, etc., will not think of considering the day of the week on which the operation will be performed as a factor of safety. It has long been known that emergency operations done at night or on the weekends have worse results than those done during the day on weekdays; but what about routine or planned operations, those (the great majority) that can be done at the surgeon’s and hospital’s leisure, as it were?

A huge statistical study done in Britain and recently published in the British Medical Journal examined the 30 day death rates after all non-emergency operations performed between 2008 and 2011 (except day cases) according to the day on which the procedure was performed.

There were in total 27,582 deaths after 4,133,345 operations, a raw rate of 6.7 per 1000: a figure that by itself would have astonished our forebears, who were used to, and took as inevitable, death rates at least a hundred times higher.

What the researchers found was that people who underwent an operation on Fridays had a death rate 44 percent higher than those who underwent an operation on Mondays, while those who underwent an operation on the weekend had a death rate 82 percent higher.