WASHINGTON: Obese people who undergo gastric bypass surgery are less likely to die from heart attack and stroke than people who receive more conventional treatment for their weight condition, a Swedish study said Tuesday.

The study, published in the January 4 issue of the Journal of the American Medical Association, included about 4,000 patients in Sweden who were recruited between 1987 and 2001.

The surgery patients either had gastric bypass (13.2 per cent), banding (18.7 per cent), or vertical banded gastroplasty (68.1 per cent), and all lost 16-23 per cent of their body weight in subsequent years.

The control group did not have any type of surgery and showed a 0-1 per cent weight loss at follow-up periods of two, 10, 15 and 20 years.

“Bariatric surgery was associated with reduced number of fatal heart attack deaths (22 in the surgery group vs. 37 in the control group),” said the study led by Lars Sjostrom of the University of Gothenburg, Sweden.

Bariatric surgery was also linked to a lower number of heart attacks overall, fewer strokes, and fewer fatal strokes.

But when the researchers looked at weight change alone, they could find no significant relationship to cardiovascular events in either group, suggesting that the weight loss itself might not be the driver of fewer deaths.

“There are many benefits to bariatric surgery and that some of these benefits are independent of the degree of the surgically induced weight loss,”said the study.

Other studies have shown that the benefits of gastric surgery for extremely obese people can include long-term changes of body weight, better quality of life, and fewer incidences of diabetes and cancer.

“The message is clear -- bariatric surgery saves lives,” said Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York, who was not involved in the study.

Roslin noted that the most common type of surgery in the study, vertical banded gastroplasty, has been replaced by newer methods that are even more effective, so the cardiovascular death risk is likely even lower today.

As many as 200,000 gastric bypass operations, in which the stomach is sectioned off so that the smaller amounts of food can fit inside, are done annually in the United States, where about a third of people are obese.