Mortality risk lower for adults who undergo bariatric surgery vs. nonsurgical controls
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Adults who undergo bariatric surgery have a lower risk for all-cause mortality compared with those who do not undergo surgery, according to findings published in Obesity.
In a retrospective data analysis, researchers found that Utah residents who underwent bariatric surgery between 1982 and 2018 had lower rates for all-cause mortality as well as death from cardiovascular disease, cancer and diabetes. The reduced mortality risk was observed for men and women and all adults older than 34 years.
“The significantly reduced mortality for CVD, cancer and diabetes supports the reported research findings that bariatric surgery improves existing comorbidities such as diabetes and also reduces the incidence of CVD, cancer and diabetes,” Ted D. Adams, PhD, MPH, director of the Intermountain Surgical Specialties/Digestive Health Clinical Program at Intermountain Healthcare in Salt Lake City; adjunct professor in the division of epidemiology, department of internal medicine and adjunct associate professor in the department of nutrition and integrative physiology at the University of Utah, told Healio. “The reporting of improved mortality is also likely to stimulate additional research efforts aimed at discovering biomolecular mechanisms that lead to nonsurgical treatment for severe obesity and for diseases such as diabetes.”
Adams and colleagues obtained data from the Utah Population Database, which contains population-based data, cancer registry records and health facility records, and is linked to medical records held by two of Utah’s largest health care providers. Adults who underwent bariatric surgery in Utah between 1982 and 2018 were identified from three large bariatric surgical practices and from the University of Utah and Intermountain Healthcare Enterprise Data warehouses. Those who underwent surgery were matched, 1:1, by sex, BMI and age to adults who did not undergo surgery. The control group was selected from Utah driver’s license and ID card records. Year of surgery was matched to the year of driver’s license application or renewal.
Bariatric surgery reduces all-cause mortality risk
There were 21,837 adults with bariatric surgery matched with adults who never had surgery. Of the surgery group, 69.2% underwent Roux-en-Y gastric bypass, 14% had a sleeve gastrectomy, 12% underwent adjustable gastric banding and 4.8% underwent a duodenal switch.
During 40 years of follow-up, 13.5% of the surgery group and 14.6% of the control group died. The surgery group had a lower risk for all-cause mortality than the nonsurgical group (HR = 0.84; 95% CI, 0.79-0.9; P < .001). All-cause mortality risk was lower for both women (HR = 0.86; 95% CI, 0.8-0.93; P < .001) and men who had surgery (HR = 0.79; 95% CI, 0.69-0.9; P < .001) compared with controls.
Adults who underwent surgery had a 26% lower risk for nonexternal deaths (P < .001), a 72% lower risk of death from diabetes (P < .001), a 29% lower risk for CVD death (P < .001), a 43% lower risk for cancer death (P < .001) and a 39% lower risk for death from chronic lung disease (P = .04) than the nonsurgical group. Death from chronic liver disease was 83% higher in the surgery group compared with controls (P = .02). The surgery group also had a 92% higher risk of death from accidents or adverse effects (P = .03) and a 140% higher risk for suicide (P < .001).
When participants were stratified by age, adults who had surgery had a lower risk for mortality than controls across all ages except for those aged 18 to 34 years. Researchers noted the higher risk for mortality among adults aged 18 to 34 years who underwent bariatric surgery was due to a higher rate of deaths from external causes.
Adams noted the researchers did not extract any psychological, behavioral or substance use data for the study, and future research should examine why there was a higher risk for mortality among younger adults and for suicide.
“Some researchers have speculated that increased substance use following surgery may be a factor for the increased suicide rate,” Adams said. “For some types of bariatric surgery there is an increased absorption of alcohol following surgery and the potential for increased disinhibition and impulsivity after certain types of bariatric surgery. Finally, surgical patients may anticipate specific or general behavioral aspects of their lives to be altered as a result of significant weight loss, and if, following surgery, the outcome is not as expected, this may contribute to mental health concerns such as depression.”
Mortality risk lower with most surgery types
After stratifying by surgery type, adults who underwent gastric bypass (HR = 0.85; 95% CI, 0.79-0.91; P < .001), gastric banding (HR = 0.72; 95% CI, 0.55-0.94; P = .017) and sleeve gastrectomy (HR = 0.49; 95% CI, 0.3-0.79; P = .004) had lower mortality risk than nonsurgical controls. No difference in mortality risk was observed with duodenal switch.
Mean survival time for all causes of death was 1.3 years longer for adults who had surgery compared with the nonsurgical group. The mean survival time for the surgery group was 1.72 years longer than controls for nonexternal deaths, but 0.4 years less for external deaths.
Adams said further research is needed into nonsurgical treatments for obesity that are just as effective as surgery and to further examine the increased mortality risk for chronic liver disease in surgical patients.
For more information:
Ted D. Adams, PhD, MPH, can be reached at ted.adams@utah.edu.
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