For many patients who are severely obese, the health benefits of gastric bypass surgery may far outweigh the risks of the procedure. New research suggests that bariatric surgery can actually increase the life expectancy of many who suffer from obesity. The details of the study appear in the recentArchives of Surgery.

Bariatric surgery is a procedure commonly performed on those who are dangerously obese to induce weight loss. Gastric bypass surgery helps to achieve weight loss by creating a small stomach pouch with a stapler device and connecting it to the distal small intestine. The upper part of the small intestine is then re-attached in a Y-shape. After the surgery, overeating is prevented by having limited stomach capacity that causes nausea and vomiting when capacity is exceeded.

The new findings, based on the creation of a mathematical model, indicate that in most cases, life expectancy is improved by opting for the gastric bypass procedure. The study suggests that as many as 5% or more of seriously obese Americans should consider the surgery.

Exceptions to beneficial improvement of life expectancy were found to be among certain high risk groups having a 30-day mortality rate of 9.5 percent or higher following surgery, or when the surgery was not deemed to have the potential of adding life-years of 2 percent or more. In the report, researcher Daniel P. Schauer, M.D., of the University of Cincinnati, and colleagues concluded, “While not all patients are guaranteed a good outcome, our model indicates that gastric bypass increases life expectancy for most patient subgroups.”

For their analysis, the researchers used a Markov state transition model to generate estimated benefits and risks of the gastric bypass procedure in morbidly obese patients. The model was based on data from two nationally representative surveys, and a 2007 observational trial of nearly 8,000 patients who had undergone gastric bypass, in addition to a control group.

The baseline 30-day mortality in the model was 0.2 percent, while the baseline efficacy of surgery in extending life expectancy was 53 percent. Results of the analysis indicated that the gastric bypass procedure slashed death rates in half during seven years of follow-up.

An average 42-year-old woman with a BMI of 45 was found to gain an estimated 2.95 years in life expectancy by opting to under gastric bypass surgery, according to the model. The greatest benefits in life expectancy were noted in younger women having a relatively high BMI. A 35-year-old woman with BMI of 55 could expect to live five extra years by having the surgery However, BMI at the time of surgery was found to be a more important factor than age. For a 35-year-old woman having a BMI of 45 the life expectancy gain would shown to be about 3.2 years, while for a woman having a similar BMI at age 55, would gain about 2.5 years.

For men, the benefits were less, especially in relation to their age. A 35-year-old man could gain about 10 percent in life expectancy, whereas a man at 75 years of age with a BMI of 35 could expect a gain of only one or two months of life. According to the authors, “Younger patients have lower surgical risk and more time over which to realize the benefits of surgery. For older patients, the gain is smaller, and for some, gastric bypass surgery will decrease life expectancy.”

Regarding their findings, the researchers wrote, “The decision analysis presented here is a step forward in understanding optimal patient selection but also highlights some of the areas for which better data are needed.”

Obesity is a growing concern among Americans and is associated with an increase in the risk of heart attack, heart disease, and other cardiovascular issues. Prior research has shown that gastric bypass procedures result in substantial, long-term loss of weight. In addition, the surgeries can lead to improved cardiovascular health, recovery from diabetes, and a significant reduction in mortality of between 23 percent and 40 percent. Bariatric surgery is recommended by the U.S. National Institutes of Health for obese people having a body mass index (BMI) of at least 40, as well as for those with a BMI of 35 when other serious medical conditions, such as diabetes, also exist.