Why Surgeries on Fridays Are Riskier

If you have the chance to plan your next surgery, you might want to avoid Fridays. A study out this week shows that surgeries scheduled right before the weekend tend to be riskier than those done earlier in the week.

Researchers in the U.S. and Canada conducted the study, published Tuesday in JAMA Network Open. Analyzing data from nearly a half million people, they found that pre-weekend surgeries had a slightly greater risk of death, complications, and readmissions compared to post-weekend surgeries. The findings suggest that hospitals can do more to keep their patients safe, such as making sure there’s sufficient staffing throughout the weekend, the researchers say.

This isn’t the first time that the study authors have looked into how the calendar might affect surgery. Last year, the team published a study examining whether surgeries performed on Friday the 13th fared worse than other typical Fridays. Thankfully, for the superstitious crowd out there, the answer appeared to be no.

But there have been other studies in the past suggesting a potential weekend effect on surgery. Anecdotally, some of the researchers themselves have also observed that patients’ care during the weekend can sometimes be worse. To get to the bottom of this question, the researchers did a deep dive through the medical records of over 400,000 residents in Ontario, Canada, who underwent common surgical procedures.

“Our study is particularly different [from others] as we studied both elective and emergent procedures, analyzed the specific contribution of physician factors (such as age, experience etc.), and looked at short-term (30 day), intermediate-term (90 day), and long-term (1 year) outcomes on the weekend effect,” study researcher Vatsala Mundra, a clinical research fellow at Houston Methodist Urology, told Gizmodo in an email.

Mundra and her colleagues found a significant, if slight, connection between the weekend timing of a surgery and graver outcomes. All in all, pre-weekend surgeries had a 5% higher combined risk of deaths, complications, and readmissions in both the short and long-term than post-weekend surgeries. This added risk was seen across different types of specialties and procedures, though it was more pronounced for elective surgeries and for certain fields like orthopedic surgery or urology.

Given that they were able to examine patient data from different hospitals, and that studies in other countries have had similar findings, the researchers say that the weekend effect is likely widespread throughout healthcare systems across the world. As for why, the most pressing factor might simply be less staffing, according to Mundra.

“Pre-weekend surgeries may be riskier because often patients that have a procedure done on Friday may have to stay over the weekend for post-operative care, and studies have shown that there is a significant decrease in physicians, nurses, and clinical staff over the weekend,” she explained. Ideally, that should also mean that hospitals can mitigate this effect by having more weekend staff and making it easier for them to get in touch with senior and primary care doctors if needed.

Mundra and her team aren’t done studying how less obvious factors might affect people’s time in the hospital. “We plan to continue researching the impact of various social and cultural phenomenon on surgical outcomes in order to highlight disparities and inefficiencies,” she said.