A growing number of people opt for surgery as a way to lose weight, but four in 10 develop complications within six months after surgery, according to a new U.S. government report.

However, one expert says that the report is based on old data and in fact, the procedure has become safer and less invasive, with only a fraction of the complications the report authors found.

In the report, published in the August issue of Medical Care, the authors looked at 2,522 insurance claims for bariatric surgery -- the general term for surgery to combat obesity -- done in 2001 and 2002.

"We found that the complication rate in the hospital was 22 percent, but it went up to 40 percent over the next six months," said lead author William Encinosa, a senior economist at the Agency for Healthcare Research and Quality, which sponsored the study.

The most common complications were dumping syndrome, which includes vomiting, reflux and diarrhea; complications resulting from the surgical joining of the intestine and stomach, such as leaks or strictures; abdominal hernias; infections and pneumonia, the researchers found.

"These additional medical utilizations are expensive," Encinosa said. Costs averaged $36,542 for obesity surgery patients who had complications in the six months after surgery, compared with an average of $25,337 for patients without complications.

Moreover, medical care costs for patients who were readmitted to the hospital because of a complication averaged $65,031, compared with $27,125 for those who didn't have to be rehospitalized.

"Insurance companies could save a lot of money if they could reduce these complications," Encinosa said. Encinosa said he didn't know how insurers could reduce costs, but he did say that as doctors develop more experience with the procedure, the rate of complications decreases.

Encinosa noted that even with a high complication rate, the surgery is cost-effective because losing weight reduces the risk of expensive diseases such as diabetes and high blood pressure. "The long-run cost benefits outweigh these complications," he said.

However, one expert said that the data used in the report is old and doesn't reflect the current procedure and its complications.

"This study was done over five years ago," said Dr. Philip R. Schauer, president of the American Society for Bariatric Surgery and director of the Bariatric and Metabolic Institute at the Cleveland Clinic Foundation. "Lots of hospitals and surgeons had just begun getting into bariatric surgery at that time, and there were no standards, so one can expect a significant complication rate," he added.

Schauer said that the American Society for Bariatric Surgery and other groups have established standards to qualify hospitals and doctors in preforming the procedure. "Complications are decreasing as there are more generalized standards across the country," he added.

When you look at the complications, many are minor ones, Schauer said. "For example, 19.5 percent of the complications were dumping, vomiting and diarrhea," he said. "These are common after weight loss surgery, self-limited and innocuous, and, in most, cases don't require medical treatment. That's nearly half of the complications." h

Schauer noted that in 2001 the most common operation was open bariatric surgery that necessitated making a large incision. A lot of the other complications are the result of this type of an open abdominal incision, including leaks or strictures, abdominal hernias and wound infection, he said.

Today, he said, most surgery is a minimally invasive laparoscopic procedure. "More than 60 percent of these operations are done laparoscopically," he said. "Within two to three years, it will be more like 90 or 95 percent."