The risk of complications such as bleeding and infection in patients undergoing an increasingly popular weight-loss surgery, also referred to as “bariatric” surgery, varies drastically based on which hospital performs it, a large study released on Monday found.

After evaluating 86,520 procedures, the researchers observed that patients undergoing bariatric surgery at a highly rated hospital were 66-percent less likely to develop a complication, including bleeding, pneumonia or heart problems, than those treated at a poorly rated hospital.

The poll comes as obese Americans - about one third of the population - are increasingly turning to bariatric surgery to shed weight. The number of surgeries has quadrupled since 2000, reaching 171,000 in 2005, according to the American Society of Bariatric Surgery.

“Bariatric surgery is the only currently effective treatment we have for the morbidly obese,” Samantha Collier, senior vice president of medical affairs at Health Grades Inc., a company that sells its ratings on hospitals’ quality measures and performed the study, said. “This shows clearly that not all hospitals perform it with the same level of quality.”

Most bariatric surgeries are gastric bypass, where the surgeon reduces the size of the stomach by separating the upper part from the lower, causing food to bypass a part of the small intestine and limiting calorie absorption.

Another common type is gastric banding, where the surgeon implants an adjustable band to literally shrink restrict the size of the stomach.

VARYING MEASURES OF SAFETY

The study, which looked at discharge records from 17 U.S. states, covered 2002 to 2004. It also found that hospitals performing more procedures were more likely to have fewer complications.

Major complications included bleeding, respiratory problems like pneumonia, and cardiac problems such as heart failure, Collier said. The mortality rate was 0.19 percent, or 2 out of every 1,000 cases, consistent with earlier national estimates, she said.

Concern over varying degrees of safety in weight-loss surgeries has led some health insurers to pull back reimbursement. The procedure’s cost averages about $25,000 per case.

The cost of the procedure jumps with complications, a recent government study found.

The U.S. Agency for Healthcare Research and Quality found that the cost jumped to $36,000 with a complication, and $65,000 if a patient returns to a hospital after going home.

Complications once a patient returns home occurs in about 40 percent of patients, that government study found.