Obese patients have a significantly higher risk of complications -- including death for morbidly obese people -- following surgery, according to a new study.

The risks include including heart attacks, infections, nerve injury and urinary tract infection.

The University of Michigan study found that morbidly obese patients had a death rate nearly twice as high as that of all other patients, as well as a higher rate of cardiac arrest.

In a review of more than 6,700 patients, 2,200 were obese, including 993 considered morbidly obese.

Obese patients were five times more likely to have a heart attack after surgery, though the rate was still just one-half of a percent.

The death rate did not vary between obese and non-obese patients, but it was nearly twice as high for those considered morbidly obese.

Because of the increased risk, the authors suggested that morbidly obese people who have outpatient surgery should undergo a 23-hour hospital stay for post-operative monitoring.

A news release said that 4 percent of surgery patients -- 1.25 million people -- experience complications each year, with an average annual cost of $25 billion. In the study, the complication rate was 7.7 percent.

The study appears in the March issue of the World Journal of Surgery.