Prevalence of depression three years before and three years after obesity surgery: Sex-stratified case-control study using German health insurance claims data between 2009 and 2015

Background: Obesity shows significant association with depression elevating morbidity burden. Obesity surgery (OS) has been proven as an effective therapy reducing weight as well as depression prevalence rates, though the latter decrease appears to be unstable over time. For a better interpretation of the time trend, data on depression prevalence in OS-patients for the period before the surgery are needed. Furthermore, sex-stratified analyses can reveal potentials for improvements in mental health care in OS-patients.

Methods: Claims data from a German statutory health insurance provider were used for the estimation of depression prevalence in patients who underwent obesity surgery in 2012 (n=340) and controls with (CGO) and without a diagnosis of obesity (CG; n=1700 each). The controls were matched to OS-patients regarding sex, age and insurance type. Sex-stratified depression prevalence was calculated between 2009 and 2015.

Results: Overall, depression rates were higher in women than in men and increased from 2009 to 2015. Depression prevalence rates differed significantly between female OS-patients and controls in every year analyzed, e.g. in 2012: 39.4% in OS (95% CI: 33.4%-45.5%) vs. 19.8% in CGO (17.6%-22.0%) and 15.4% in CG (13.4%-17.4%). In men, no significant differences between OS-patients and controls could be observed at any time. After OS, depression prevalence rates dropped in women, then gradually increased until 2015. Also in male OS-patients, depression prevalence decreased in the year after OS and increased in the following years. In both sexes, the prevalence rates in 2015 did not significantly differ from the rates in 2012 (year of OS).

Conclusions: We found a decrease of depression prevalence rates in the first year after OS in both sexes followed by an increase in the subsequent 2 years. OS appears to have a short-term effect on the prevalence rates of depression followed by a subsequent increase paralleling the increase over time found in the non-OS control groups. Due to the sex-stratified approach, differential results in the comparison of depression prevalence between OS-patients and controls became apparent. Depression prevalence was significantly increased three years before and after OS compared to controls in women, but not in men. Measures to perpetuate the decrease in depression prevalence rates after OS should be implemented during post-operative treatment.