Impact of bariatric surgery on clinical depression. Interrupted time series study with matched controls

Obesity is associated with depression. This study aimed to evaluate whether clinical depression is reduced after bariatric surgery (BS).

Obese adults who received BS procedures from 2002 to 2014 were sampled from the UK Clinical Practice Research Datalink. An interrupted time series design, with matched controls, was conducted from three years before, to a maximum of seven years after surgery. Controls were matched for body mass index (BMI), age, gender and year of procedure. Clinical depression was defined as a medical diagnosis recorded in year, or an antidepressant prescribed in year to a participant ever diagnosed with depression. Adjusted odds ratios (AOR) were estimated.

There were 3045 participants (mean age 45.9; mean BMI 44.0kg/m(2)) who received BS, including laparoscopic gastric banding in 1297 (43%), gastric bypass in 1265 (42%), sleeve gastrectomy in 477 (16%) and six undefined. Before surgery, 36% of BS participants, and 21% of controls, had clinical depression; between-group AOR, 2.02, 95%CI 1.75-2.33, P<0.001. In the second post-operative year 32% had depression; AOR, compared to time without surgery, 0.83 (0.76-0.90, P<0.001). By the seventh year, the prevalence of depression increased to 37%; AOR 0.99 (0.76-1.29, P=0.959).

Despite matching there were differences in depression between BS and control patients, representing the highly selective nature of BS.

Depression is frequent among individuals selected to undergo bariatric surgery. Bariatric surgery may be associated with a modest reduction in clinical depression over the initial post-operative years but this is not maintained.