Gastric Bypass Surgery Adds Years of Life
Weight Loss Surgery and Life Expectancy
By Mark Stibich, Ph.D., About.com
Updated: September 13, 2007
longevity.about.com
For those who are obese, gastric bypass can reduce the risk of death by 40% over a 7-year period, according to a study in the New England Journal of Medicine.
Gastric Bypass Benefits: The Research
The study examined the medical records of almost 10,000 gastric bypass patients, from 1984 to 2002, and compared them to data from almost 10,000 severely obese persons who had applied for driver’s licenses.
Researchers matched individuals in each group based on age, sex, and BMI--this is a way to ensure that these other factors don't play into the results. They then looked up each individual in the National Death Index to learn about any deaths that occurred over a 7-year period.
The Findings
People who underwent gastric bypass surgery had a 40% reduction in the rate of death compared to their obese counterparts. More specifically, they had a 56% reduction in death from coronary artery disease, a 92% reduction in death from diabetes, and a 60% reduction in death from cancer.
Oddly, the group that had gastric bypass surgery had a 58% increased risk of death by injuries, suicide and other non-disease causes.
Benefits of Gastric Bypass Surgery
A second study enrolled more than 4,000 obese participations. About half of those people underwent bariatric surgery (the most common type of which is gastric bypass surgery), and the other half were given non-surgical treatment. The participants were followed for an average of 10.9 years.
This study found that the non-surgery subjects had less than a 2% change in body weight over the follow-up period. The bariatric surgery group, on the other hand, reported large changes in body weight:
Gastric Bypass patients lost an average of 32%
Vertical-banded gastroplasty patients lost an average of 25%
Banding patients lost an average of 20%
After 10 years, these patients were able to keep the weight off. Ten years post-surgery:
Gastric bypass patients were 25% of their pre-surgery weight.
Vertical-banded gastroplasty patients were 16% of their pre-surgery weight.
Banding patients were 14% of their pre-surgery weight.
Studies have shown that a weight loss of 12% can reduce diabetes risk. The people in the surgery group were 24% less likely to die over a ten-year period.
The Bottom Line
These findings emphasis the health benefits of losing weight. Obesity is linked to dramatic increases in the risk of heart disease, diabetes and cancer. Losing weight can dramatically reduce those risks, as seen in this study.
Gastric bypass surgery is an option for people who have not been able to lose weight through lifestyle modifications. Once weight is reduced, controlling blood sugar, high blood pressure and other health conditions becomes much easier.
Another outcome of these studies may be the lowering of the BMI threshold for gastric bypass surgery. Until these studies came out, there was no solid evidence that gastric bypass surgery increased life expectancy. Now that that evidence exists, we may see gastric bypass surgery recommendations being made for more and more people.
Sources:
Adams TD, et al. Long-Term Mortality after Gastric Bypass Surgery. New England Journal of Medicine. Vol. 357:753-761. August 23, 2007, Number 8.
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futurepundit.com
Epidemiologic studies of the relation between overweight and mortality typically must address three principal concerns [6]. First, in many populations, cigarette smokers tend to be leaner than nonsmokers. Because cigarette smoking is such a strong risk factor for mortality, failure to adjust for this adequately can lead to confounding, with the erroneous conclusion that leanness carries increased risk of death. Statistical adjustment for smoking is often insufficient to account for this difficulty. Smoking can lead to medical conditions, sometimes sub-clinical, that are associated with decreased body weight, such as chronic obstructive pulmonary disease. The presence of symptoms or diagnosed conditions may induce smokers to quit. Moreover, the intensity of smoking is related to both risk of death and body mass index. For these reasons, the best way to assess the impact of overweight on risk of mortality is simply to exclude current and past smokers. Kaprio and colleagues' study differentiated only current smoker or nonsmoker. Thus, never-smokers were included in the same category as past smokers, regardless of how much the past smokers had smoked or their reasons for quitting.
A second difficulty in some epidemiologic studies is the inclusion of intermediary factors as co-variates. Weight loss improves hypertension and diabetes, so including these as co-variates would tend to attenuate the apparent benefit of weight loss. In the present study, the authors appropriately excluded people with diabetes, and adjustment for hypertension appeared to have little impact.
The third and most difficult issue in studies of overweight and mortality is reverse causation, the impact of disease on body weight. This can occur either through the biological impact of a condition (diagnosed or preclinical) or as an inducement to attempt to lose weight as a means to improve health. The authors' keen recognition of this problem provides a significant strength to the present study. The authors appropriately excluded individuals with a wide range of conditions to identify an apparently healthy cohort. This critical step is often ignored. Sometimes, investigators also exclude deaths that occur in the first few years after follow-up, to reduce the impact of reverse causation. Such lagged analyses can be helpful, but some chronic conditions of long duration, such as depression, chronic lung disease, and heart failure (conditions that often may not reach the level of clinical diagnosis) can lead to lower body weight and higher mortality risk. |
