(HealthDay)—When patients are pushed out of the hospital after hip surgery to make room for others, the odds of dying increase, according to a recent study from Norway.

When beds are in short supply, are forced out, researchers say. Fridays, the day before holidays and times when hospitals are overbooked are prime times for patients to be discharged, they report.

"Patients who are operated on for hip fractures have a higher risk of dying if they are discharged from the hospital early for space reasons," said study co-author Johan Bjørngaard, a professor of public health and nursing at the Norwegian University of Science and Technology in Trondheim.

Among 60,000 of these patients over 70, 13% died within 60 days of surgery and 27% within the first year.

There was a difference of about 4 percentage points in the 60-day mortality rate between patients discharged for space reasons and other patients, the researchers found.

The average age for the hip patients is 84 years old, according to the study, and many suffer from , making them a very vulnerable group.

Nonetheless, in Norway, the discharge time after has been getting shorter. When it's due to better treatment, that's good, but when it stems from bed capacity, that can be bad, the researchers noted.

"The problem is that it's really difficult to separate these reasons from each other. We've tried to focus the effect of hasty discharges, but we have to account for several assumptions in the analysis," Bjørngaard said in a university news release.

In 2016, half of patients had bed rest for five days or less, researchers said, compared to only 25% in 2010.

"We need to have a better idea about what the most comprehensive solution is," Bjørngaard said.

The findings were recently published in the journal Clinical Epidemiology.

More information: Learn more about hip replacement from the U.S. National Library of Medicine.