Are Fridays really the riskiest days for elective surgery?

People having elective surgery on Fridays are no more likely to die than people who undergo procedures any other weekday, a large Canadian study suggests.

Prior studies have shown a higher risk of death among patients opting for surgery on Fridays, the authors behind the new study said. One British study found a 44 percent increase in death risk among patients who had surgery on a Friday as compared to a Monday.

Canadian investigators wanted to determine whether this “weekday effect” was real. Are surgeons who operate on Fridays less experienced? Does that inexperience translate into worse outcomes?

The researchers examined close to 403,000 elective, daytime surgical procedures performed by nearly 1,700 different surgeons at Ontario hospitals over a 10-year period – from 2002 to 2012.

“Yes, surgeons who operate on Friday are less experienced than those that operate on Tuesday, Wednesday and Thursday,” said Dr. Luc Dubois, the study’s lead author. “But they’re also less experienced on Monday as well,” he said.

Dubois is an assistant professor at Western University in London, Ontario.

“It really looks like the senior surgeons are kind of cherry-picking the middle days of the week,” he observed.

Dubois suspects that surgeons know if they operate on a Friday, they may be providing post-operative care over the weekend.

However, patients’ risk of death within 30 days of surgery was similar, no matter what weekday the procedure took place, the new study found.

“It means that people are getting consistent care across the week,” Dubois said.

As for Friday surgery in the United States? Dubois said it’s hard to extrapolate the study findings because the American and Canadian health systems are different.

But Dr. Keith Naunheim, a St. Louis-based surgeon who serves on the board of the Society of Thoracic Surgeons, cites reasons for optimism.

The U.S. patient safety movement over the past decade has led to numerous improvements, he said. These include improved staffing levels on weekends and pre-surgical “time outs” to assure that the right patient is having the right surgery on the right part of the body, he added.

What’s more, Naunheim said, the Canadian and U.S. systems really aren’t that different.

“I think we might see the same thing here in the U.S.,” said Naunheim, who’s also chief of cardiothoracic surgery at Saint Louis University Medical Center.

The study findings were published Oct. 17 in CMAJ (Canadian Medical Association Journal).

The “weekday effect” is well known but less studied in the United States.

Preliminary research reported at a 2013 meeting of the American College of Surgeons looked at a separate but related phenomenon – dubbed the “weekend effect.” It found patients having appendix removal on a Saturday or Sunday were no more likely to experience complications after surgery than those who had the operations on a weekday. However, weekend patients faced hospital charges that were more than $400 higher, the study found.

The Canadian researchers accessed data from the Institute for Clinical Evaluative Sciences, a nonprofit medical data repository. It contains information on hospital care and physician services provided to every patient in Ontario, Dubois said.

The project was supported by a grant from the Academic Medical Organization of Southwestern Ontario.

The study examined 12 surgeries, all commonly performed on an elective basis and typically requiring at least a two-day hospital stay. These included procedures on the esophagus, kidney, pancreas, colon and liver, as well as hip, knee and aortic valve replacements.

Surgeon experience was highest on Tuesdays and Wednesdays, with an average of 19 years in practice, the study found. It was lowest on Mondays and Fridays, averaging 16 years.

Median annual procedure volume also varied by day of week. It was highest for surgeons who operated on Tuesdays and lowest on Fridays, the findings showed.

The risk of patients being admitted to the intensive care unit was slightly higher on a Friday than a Monday, the study found.

But risk of death within 30 days of surgery was no greater for surgery on a Friday than other weekdays.

At least in Ontario, “I think the takeaway for patients is that if you show up on a Friday, you’re going to be OK,” Dubois said.

And thanks to stricter pre-operative processes and nurse-to-patient ratios, Naunheim believes Friday surgeries in the United States are as safe as any other day of the week.

“I think you should be confident you’re getting the best care possible,” he said.