Preoperative comorbidities as a predictor of EBWL after bariatric surgery: a retrospective cohort study

The purpose of this study is to investigate the impact of preoperative comorbidities, including depression, anxiety, type 2 diabetes mellitus, obstructive sleep apnea, hypothyroidism, and the type of surgery on %EBWL (percent estimated body weight loss) in patients 1 year after bariatric surgery. Patients who choose to undergo bariatric surgery often have other comorbidities that can affect both the outcomes of their procedures and the postoperative period. We predict that patients who have depression, anxiety, diabetes mellitus, obstructive sleep apnea, or hypothyroidism will have a smaller change in %EBWL when compared to patients without any of these comorbidities.

Data points were retrospectively collected from the charts of 440 patients from March 2012-December 2019 who underwent a sleeve gastrectomy or gastric bypass surgery. Data collected included patient demographics, select comorbidities, including diabetes mellitus, obstructive sleep apnea, hypothyroidism, depression, and anxiety, and body weight at baseline and 1 year postoperatively. Ideal body weight was calculated using the formula 50 + (2.3 × height in inches over 5 feet) for males and 45.5 + (2.3 × height in inches over 5 feet) for females. Excess body weight was then calculated by subtracting ideal body weight from actual weight at the above forementioned time points. Finally, %EBWL was calculated using the formula (change in weight over 1 year/excess weight) × 100.

Patients who had a higher baseline BMI (p < 0.001), diabetes mellitus (p = 0.026), hypothyroidism (p = 0.046), and who had a laparoscopic sleeve gastrectomy rather than Roux-en-Y gastric bypass (p < 0.001) had a smaller %EBWL in the first year after bariatric surgery as compared to patients without these comorbidities at the time of surgery. Controversially, patients with anxiety or depression (p = 0.73) or obstructive sleep apnea (p = 0.075) did not have a statistically significant difference in %EBWL.

A higher baseline BMI, diabetes mellitus, hypothyroidism, and undergoing laparoscopic sleeve gastrectomy may lead to lower %EBWL in the postoperative period after bariatric surgery. At the same time, patients' mental health status and sleep apnea status were not related to %EBWL. This study provides new insight into which comorbidities may need tighter control in order to optimize weight loss outcomes after bariatric surgery.