Patients who undergo procedures on their surgeon’s birthday are more likely to die within a month than those who have surgery on other days of the year, a study suggests.

In the analysis of nearly one million procedures done in the US, slightly more than 2000 were performed on a surgeon’s birthday, according to the study in the BMJ.

The adjusted 30-day mortality for patients who had a procedure on the surgeon’s birthday was 6.9%, compared to 5.6% when the surgery was on a different day.

Study coauthor Dr Yusuke Tsugawa, at the David Geffen School of Medicine at the University of California, Los Angeles, says distractions on the celebratory day may be affecting surgeons’ performance.