People who have had bariatric surgery live three years longer, on average, than those given conventional treatment for their obesity, a University of Gothenburg study has reported. Compared with the general population, however, both groups' excess mortality is higher. The results published in the New England Journal of Medicine, ‘Expectancy after Bariatric Surgery in the Swedish Obese Subjects Study, New England Journal of Medicine ‘, are based on the Swedish Obese Subjects (SOS) study, which started in 1987 and is led from the Sahlgrenska Academy, University of Gothenburg.
"Now, for the first time, we've got a measure of how much bariatric surgery prolongs life expectancy for the average patient,” said Dr Lena Carlsson Ekander, Professor of Clinical Metabolic Research at Sahlgrenska Academy, who has been responsible for the SOS study since 2005 and is the lead author of the paper. “But it's important to point out that it's a matter of averages. Not all patients are the same, so you can't draw the conclusion that everyone who gets the operation done lives three years longer.”
The study comprises data on 2,007 adult patients who had undergone bariatric surgery and a control group of 2,040 given conventional (nonsurgical) treatment for obesity. Also included was a representative reference group of 1,135 people from the general population. At the time of the analysis (December 2018), the median duration of follow-up for mortality was 24 years (interquartile range, 22 to 27) in the surgery group and 22 years (interquartile range, 21 to 27) in the control group; data on mortality were available for 99.9% of patients in the study.
In the SOS reference cohort, the median duration of follow-up was 20 years (interquartile range, 19 to 21), and data on mortality were available for 100% of participants. In total, 457 patients (22.8%) in the surgery group and 539 patients (26.4%) in the control group died (hazard ratio, 0.77; 95% confidence interval [CI], 0.68 to 0.87; P<0.001). The corresponding hazard ratio was 0.70 (95% CI, 0.57 to 0.85) for death from cardiovascular disease and 0.77 (95% CI, 0.61 to 0.96) for death from cancer.
The adjusted median life expectancy in the surgery group was 3.0 years (95% CI, 1.8 to 4.2) longer than in the control group - but 5.5 years shorter than in the general population. The 90-day post-operative mortality was 0.2%, and 2.9% of the patients in the surgery group underwent repeat surgery.
It has been known for some time that bariatric surgery brings about lasting weight loss and lowered risks of cardiovascular disease, type 2 diabetes and cancer, leading to lower mortality. On the other hand, to what extent this translates to extension of life expectancy after bariatric surgery has been unknown.
Despite the beneficial effects of bariatric surgery - the reduced risk of worsening health and premature death - still only a minority of the patients eligible for surgery actually undergo an operation. The researchers emphasise the importance of patients getting appropriate information to make an informed choice when considering obesity treatment.
"In this study, we investigated mortality over as long as three decades. In addition, we estimated life expectancy after bariatric surgery and regular obesity treatment and compared it with life expectancy in the general population," added Ekander. "Obesity has long been known to reduce average life expectancy by some five to ten years. Our study shows that bariatric surgery prolongs it by three years. But even after surgery, patients still have a shorter life expectancy than the general population. That's why it's very important for bariatric patients to be offered adequate postoperative monitoring and follow-up.”