But there is an ever increasing number of bariatric surgeries being performed to induce weight loss which keeps rising dramatically. These procedures are technically demanding and performed on patients whose obesity and related conditions may put them at risk for complications after surgery. Therefore, it is important to understand risk factors that may influence risk, including body mass index (BMI), age, other illnesses and choice of procedure, the authors write.

Robert W. O'Rourke, M.D., and colleagues at the Oregon Health and Science University, Portland, reviewed data from 452 patients (372 women and 80 men, average age 44 years) undergoing inpatient bariatric procedures at the university between 2000 and 2003. The patients received either gastric bypass surgery, which involves sectioning off a small portion of the stomach into a pouch that connects directly to the small intestine, or biliopancreatic diversion with duodenal switch, a less commonly used procedure in which surgeons remove part of stomach but leave a slightly larger pouch and then also perform an intestinal bypass-like procedure by attaching the duodenum (the first part of the small intestine) to the lower part of the small intestine. Researchers examined several variables, including patients' age, BMI (calculated by dividing their weights by the square of their heights), gender, surgeon experience, other illnesses, type of procedure and whether they underwent open or laparoscopic (minimally invasive) surgery.

Participants lost an average of 54 percent of their excess weight in the year following surgery.

During the study, which followed patients for an average of 419 days

1.) four (.9 percent) died

2.) 10 percent had major complications

3.) 13 percent had minor complications

4.) Patients who were age 60 years or older were more likely to develop complications than younger patients, a risk that appeared to increase with each additional year.

The duodenal switch procedure was also associated with more complications than gastric bypass surgery. BMI, sex, diabetes, surgical approach (open vs. laparoscopic) and surgeon experience did not appear to be associated with increased risk for complications.

Given the amount of risks for the patient the surgeons should warn older adults and those considering duodenal switch procedures of the risks involved. "While some investigators have suggested a specific age limit as an absolute contraindication to bariatric surgery, we do not employ such limits for our patients," they write. "We nevertheless approach older patients with caution, especially in light of recent data that suggest that the benefits of bariatric surgery with respect to longevity may wane in older patients."