But a history of obesity shortens life expectancy

Researchers who followed more than 2,000 bariatric surgery patients for a median of 24 years confirmed that the weight loss surgery can add years to life.

This latest report follows a landmark 2007 report from the Swedish Obesity Study (SOS) that confirmed a survival benefit for bariatric surgery.

“After an additional 13 years of follow-up, we now report that the difference in mortality persisted and that bariatric surgery was associated with a lower risk of death from both cardiovascular diseases and cancer. In addition, we show that life expectancy among patients with obesity who were given usual care was approximately 8 years shorter than in the general population, and this difference was decreased by bariatric surgery, which was associated with life expectancy that was approximately 3 years longer than that associated with usual care,” wrote Lena M.S. Carlsson, MD, PhD of the Institutes of Medicine at the University of Gothenburg, Gothenburg, Sweden, and colleagues in The New England Journal of Medicine.

But the SOS also found that obesity has long lasting sequelae that bariatric surgery could not erase: the median life expectancy for the bariatric surgery patients was still 5.5 years shorter than that of the general population.

The SOS investigators reported outcomes for 2,007 obese participants in the surgery group and 2,040 obese patients in a control group. The researchers used 1,135 participants from the SOS reference study as a reference cohort, representing the general population.

“The inclusion criteria were an age between 37 and 60 years and a body-mass index (BMI, the weight in kilograms divided by square of the height in meters) of at least 34 for men and at least 38 for women,” they wrote.

“Patients in the surgery group underwent banding (18%), vertical banded gastroplasty (69%), or gastric bypass (13%). In total, 56 patients emigrated, 392 had a change in the obesity intervention (290 control-group patients underwent bariatric surgery, and 102 surgery-group patients underwent surgery to restore normal anatomy), 3 patients withdrew consent, and 2,600 patients were alive at the end of follow-up,” they explained.

“The median life expectancy was 2.4 years (95% CI, 1.2 to 3.5) longer in the surgery group than in the control group (P<0.001) (adjusted difference, 3.0 years; 95% CI, 1.8 to 4.2; P<0.001) and was 7.4 years (95% CI, 5.4 to 9.4) longer in the reference cohort than in the control group (P<0.001) (adjusted difference, 8.5 years; 95% CI, 6.4 to 10.5; P<0.001),” Carlsson and colleagues reported. “In the surgery group, the median life expectancy was 5.5 years (95% CI, 3.4 to 7.6) shorter (adjusted difference) than in the reference cohort (P<0.001).”

Overall, the leading causes of death were cardiovascular disease and cancers, but there was some variation by treatment arm.

For example, cardiovascular diseases caused the death of 167 surgery patients and 221 control group patients. That worked out to a 30% decrease in relative risk for cardiovascular mortality in the surgery group — the hazard ratio was 0.51 (95% CI 0.33-0.79) for myocardial infarction, 0.52 (95% CI, 0.31 to 0.88) for heart failure, and 0.45 (95% CI, 0.24 to 0.84) for stroke.

Breaking down the cancer mortality, there were 135 cancer-related deaths in the surgery arm versus 165 in the control group (HR, 0.77; 95% CI, 1.08-3.17). “Furthermore, 38 deaths in the surgery group and 20 deaths in the control group were caused by factors other than disease (alcoholism, suicide, and trauma) (hazard ratio, 1.85; 95% CI, 1.08 to 3.17),” they wrote.

Obesity by itself is known to shorten life, and even after bariatric surgery participants had above-normal BMI, the authors noted. Additionally, more “frequent occurrence of alcoholism, suicide, and trauma and a larger number of related deaths have previously been observed among patients with obesity who undergo bariatric surgery than among those who do not undergo surgery. In the SOS study, we have found a higher risk of alcohol abuse, suicide and self-harm, and serious fall-related injuries among patients with obesity who have undergone bariatric surgery than among those who have not,” they wrote.

The investigators noted that the participants were not randomly assigned to surgery or control groups because, at the time the study was initiated, bariatric surgery was considered risky and thus ethical considerations were a factor in assignment, which is a limitation of the study. “Another limitation of the present study is that it included surgical techniques that are rarely used today,” they added. “However, the inclusion of older methods is difficult to avoid in studies with long follow-up periods. Our study is also limited by the age of the patients at inclusion. It is possible that the average gain in life expectancy would be greater in a younger study population than in the middle-aged cohort we have examined. However, our study shows that the benefit of bariatric surgery with respect to mortality persists in our aging cohort.”

  1. Note that some of the surgical techniques used in the SOS study are not commonly used today, which may limit the generalizability of the findings.

  2. In the SOS trial, bariatric surgery was associated with a lower risk of death from both cardiovascular diseases and cancer.

Peggy Peck, Editor-in-Chief, BreakingMED™

The study was supported by grants from the Swedish Research Council, the Swedish state under an agreement between the Swedish government and the county councils, the ALF (Avtal om Läkarutbildning och Forskning) agreement, the Swedish Diabetes Foundation, the Swedish Heart-Lung Foundation, the Novo Nordisk Foundation, and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

Lena Carlsson reported receiving consulting fees from Johnson & Johnson Healthcare Systems and grant support, paid to her institution, from the Novo Nordisk Foundation, and Björn Carlsson reported being employed by and owning stock in AstraZeneca.

No other potential conflict of interest relevant to this article was reported.

Cat ID: 159

Topic ID: 97,159,914,187,795,192,51,518,917,925,159