Preop mental illness doesn't affect weight loss after bariatric surgery

The presence of a mental illness may not have a detrimental effect on the amount of weight lost after bariatric surgery, but may increase the use of post-operative acute care, according to research published in the journal Obesity, the scientific journal of The Obesity Society.

“Our findings suggest that this powerful weight loss tool can be equally effective for different groups of patients regardless of pre-existing mental health conditions,” said senior author Kristina Henderson Lewis, MD, MPH, SM, assistant professor, Department of Epidemiology & Prevention Division of Public Health Sciences at Wake Forest Baptist Medical Center, Winston-Salem, NC.

In this multi-center study, Dr. Lewis and colleagues compared outcomes in 8,192 patients (mean age: 44.3 years; 79.9% female; 45.6% white) from several US health care systems between 2012 and 2013. They divided patients into four groups for comparison, including the following:

• Patients with no mental illness (43%),
• Patients with mild-to moderate depression or anxiety (44%),
• Patients with severe depression or anxiety (6%), and
• Patients with bipolar, psychosis, or schizophrenia spectrum disorders (6%).

In all, 57% of subjects had a pre-operative mental illness. Mean preoperative BMI was 43.7 kg/m², and 59.8% underwent vertical sleeve gastrectomy (VSG), 37.4% had Roux-en-Y gastric bypass (RYGB), and 2.7% underwent other procedures.

Upon reviewing data from electronic health records, Dr. Lewis and fellow researchers used generalized estimating equations with B-spline bases to compare weight loss trajectories between these groups, and zero-inflated Poisson and negative binomial regression to compare all-cause emergency department (ED) visits and hospital days up to 2 years after surgery.

They found no differences between the four groups in total weight loss or BMI. The BMI change nadir in patients with no mental illness was -10.8 kg/m², with a corresponding maximum percent total weight loss of 25.0%, and this occurred at roughly 12 months post-operatively. But in patients with severe depression or anxiety and those with bipolar, psychosis, or schizophrenia spectrum disorders, there were higher follow-up occurrences of ED visits and hospital days compared with patients with no mental illness.

Patients with bipolar, psychosis, or schizophrenia disorders were 40% less likely compared with the latter to have no ED visits at 3 months after surgery; and this pattern continued through 1 and 2 years of follow-up. Among patients with any ED visits, those with bipolar, psychosis, or schizophrenia spectrum disorders had 70% more ED visits compared with those with no mental illness at 1 and 2 years after surgery.

In addition, patients with severe anxiety or depression were less likely to have zero ED visits compared with those with no mental illness. Among the subgroup of patients who had any ED visits, those with severe depression or anxiety had more ED visits compared with those with no mental illness at all three follow-ups, occurring at 3 months, 1 year, and 2 years.

“Many clinicians are hesitant to consider bariatric surgery in the mentally ill population due to the assumption that they will not fare well. This research counters those assumptions, showing no difference, on average, in weight loss in the mentally ill versus non-mentally ill population,” said Scott Kahan, MD, MPH, FTOS, Director of National Center for Weight and Wellness, and spokesperson for The Obesity Society.

“No prior research has evaluated this research question in a large and detailed study group. While all potential surgical patients should receive a thorough evaluation prior to considering surgery, this research suggests that there appears to be no outright reason to deny consideration of bariatric surgery in patients with mental illness who otherwise are good surgical candidates,” Dr. Kahan concluded.