Predictors of Success in Bariatric Surgery: the Role of BMI and Pre-operative Comorbidities

Background: This is a retrospective review of 204 patients who underwent bariatric surgery. The impact of weight regain (WR), pre-operative comorbidities and BMI values on the recurrence of comorbidities was evaluated, and an equation was elaborated to estimate BMI at 5 years of bariatric surgery.

Methods: Pre-operative data, after 1 year and after 5 years, was collected from the medical records. Descriptive analyses and bivariate hypothesis tests were performed first, and then, a generalised linear regression model with Tweedie distribution was adjusted. The hit rate and the Kendall coefficient of concordance (Kendall's W) of the equation were calculated. At the end, the Mann-Whitney test was performed between the BMI, WR and the presence of comorbidities, after a post-operative period of 5 years.

Results: The adjustment of the model resulted in an equation that estimates the mean value of BMI 5 years after surgery. The hit rate was 82.35% and the value of Kendall's W was 0.85 for the equation. It was found that patients with comorbidities presented a higher median WR (10.13%) and a higher mean BMI (30.09 kg/m) 5 years after the surgery.

Conclusions: It is concluded that the equation is useful for estimating the mean BMI at 5 years of surgery and that patients with low pre-operative HDL and folic acid levels, with depression and/or anxiety and a higher BMI, have a higher BMI at 5 years of surgery and higher incidence of comorbid return and dissatisfaction with post-operative results.