Impact of Bariatric Surgery on Risk of Mortality, Diabetes, and Other Conditions

A national assessment of more than 1.5 million patients from the United Kingdom is detailing the specific associations between bariatric surgery and decreased incidence of mortality and other obesity-related diseases.

A comparison between nearly 270,000 patients who underwent bariatric surgery to 1.27 million controls, results of the study indicate bariatric surgery was associated with decreases of 35% or more in rates of all-cause mortality, cardiovascular mortality, and the incidence of diabetes, hypertension, and dyslipidemia.

“Healthcare providers may use the data on relative risk reduction as part of the discussion with patients considering bariatric surgery,” noted study investigators.

To provide clinicians with a more accurate overview of outcomes following bariatric surgery in obese individuals, a group of investigators from the Imperial College London and Musgrove Park Hospital designed their analysis using data from studies published within Medline, Embase, and Web of Science databases. For inclusion in the study, investigators required articles to be national or regional administrative database cohort studies comparing risk of long-term mortality or incident obesity-related diseases for patients who have undergone bariatric surgery versus appropriate control groups. Additionally, published articles needed to have a minimum follow-up period of 18 months and be published between January 1, 2000 and January 31, 2020.

The primary aim of the analysis was to assess the hazard ratios for all-cause mortality and the pooled odds ratios for incident disease. In total, investigators identified 18 studies with a median follow-up time of 55 months meeting their inclusion criteria.

From the 18 studies, investigators identified information related to 1,539,904 patients for the current study. Of these, 269,818 underwent bariatric surgery and 1,270,086 were included as controls subjects. Of the 269,818 who underwent bariatric surgery, 137,578 underwent gastric bypass, 58,916 underwent a sleeve gastrectomy, 52,973 underwent an adjustable gastric band, and 6397 underwent vertical banded gastroplasty, and 1002 underwent biliopancreatic diversion.

In 11 studies assessing all-cause mortality, investigators noted a significant reduction in relative risk of long-term all-cause mortality in patients who underwent bariatric surgery when compared with controls (POR, 0.62; 95% CI, 0.55-0.69; P <.001). In the 3 studies assessing cardiovascular mortality, those undergoing bariatric surgery had a significantly reduced relative risk of cardiovascular mortality compared to those in the control group (POR, 0.50; 95% CI, 0.35-0.71; P <.001).

Additionally, the analyses indicated bariatric surgery was strongly associated with reduced incidence of type 2 diabetes (POR, 0.39; 95% CI 0.18-0.83, P=.010), hypertension (POR, 0.36; 95% CI, 0.32-0.40, P <.001), dyslipidemia (POR, 0.33; 95% CI 0.14-0.80, P=.010), and ischemic heart disease (POR, 0.46; 95% CI, 0.29-0.73, P=.001). Of note, 6, 5, 2, and 5 studies included in the analyses for each of these diseases, respectively.

Investigators cautioned against over-interpretation of study results without consideration of the possible limitations.

“Our results represent real-world data that may be generalizable to routine clinical practice. As further data accumulate, it may become clearer whether bariatric surgery reduces the incidence of new-onset obstructive sleep apnea or venous thromboembolism,” wrote investigators.

This study, “Association of bariatric surgery with all-cause mortality and incidence of obesity-related disease at a population level: A systematic review and meta-analysis,” was published in PLOS Medicine.