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Surgical mortality

Bariatric surgery reduces long-term mortality

The effect of gastric banding and gastric by-pass was similar for global and all-cause mortality

Bariatric surgery has been associated with improved quality of life, weight loss and remission of type 2 diabetes, however, comprehensive research from Italy including some 44,000 patients has reported that it reduces long-term mortality in operated participants in comparison with non-operated participants.

The study, published in the March 2011 issue of the Annals of Surgery, reported that patients undergoing either bypass or banding procedures reduced a their odds of dying by nearly half over an average study period of seven to eight years.


Study design

Drs Antonio Pontiroli and Alberto Morabito (University of Milan, Italy) performed a systematic review and meta-analysis of eight clinical trials published as full articles dealing with cardiovascular (CV) mortality, all-cause mortality (non-cardiovascular), and global mortality (sum of CV and all-cause mortality). Pooled-fixed effects of estimates of the risk of mortality in participants undergoing surgery were calculated compared with controls.

"Both gastric banding and gastric by-pass reduce mortality with a greater effect of the latter on cardiovascular mortality" Antonio Pontiroli and Alberto Morabito

They identified eight trials, which included an average of seven-and-a-half years of follow-up on a total of more than 44,000 men and women. About 14,000 of the participants actually underwent bariatric surgery, the rest served as control subjects for comparison.


Of 44,022 participants from the trials (14,052 undergoing surgery and 29,970 controls), death occurred in 3,317 participants (400 in surgery, 2,917 in controls); when the kind of death was specified, 321 CV deaths (118 in surgery, 203 in controls), and 523 all-cause deaths (218 in surgery, 305 in controls) occurred. Compared with controls, surgery was associated with a reduced risk of global mortality (OR=0.55, CI, 0.49–0.63), of CV mortality (OR=0.58, CI, 0.46–0.73), and of all-cause mortality (OR=0.70, CI, 0.59–0.84).


The study showed that data of all-cause mortality were not heterogeneous; heterogeneity of data of CV mortality decreased when studies were grouped according to size (large vs small studies). The reduction of risk was smaller in large than in small studies (OR=0.61 vs 0.21, 0.63 vs 0.16, 0.74 vs 0.35 for global, CV, and all-cause mortality, respectively).

The effect of gastric banding and gastric by-pass (3,797 vs 10,255 interventions) was similar for global and all-cause mortality (OR=0.57 vs 0.55, and 0.66 vs 0.70, respectively), different for CV mortality (OR=0.71 vs 0.48). At meta-regression analysis, a trend for a decrease of global mortality (Log OR) linked to increasing BMI appeared.


Of the 3,317deaths across the studies, 2.8% had a bariatric procedure. Similar patients who did not have surgery made up 9,7% of the total deaths. Among morbidly obese patients, bariatric surgery resulted in a 45% lower chance of death over seven to eight years. A similar benefit was found when the team looked specifically at heart-related deaths.


Overall, death rates were comparable for the approximately 10,000 gastric banding and 4,000 gastric bypass surgeries, although the protective effects on heart-related deaths differed: compared to no surgery, banding provided 29% lower odds of heart-related death versus a 52% risk reduction with bypass, the researchers reported. Furthermore, after drastic reductions in pounds, patients tend to find that they need fewer medications for the treatment of obesity-related conditions, and that they take fewer sick days.



Conclusion


"This meta-analysis indicates that bariatric surgery reduces long-term mortality, and the risk reduction is smaller in large than in small studies,” concluded Pontiroli and Morabito. "Both gastric banding and gastric by-pass reduce mortality with a greater effect of the latter on cardiovascular mortality."

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