Supplementary Material for: 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.

背景：肥胖与抑郁症存在显著关联，增加了发病负担。肥胖手术（Obesity surgery, OS）已被证实是一种有效疗法，可减轻体重并降低抑郁症患病率，尽管后者的下降随时间推移似乎并不稳定。为更好地解释这一时间趋势，需获取OS患者术前阶段的抑郁症患病率数据。此外，性别分层分析可揭示OS患者心理保健的改进潜力。

方法：利用德国某法定健康保险机构的索赔数据，估算2012年接受OS的患者（n=340）、有肥胖诊断的对照组（CGO）及无肥胖诊断的对照组（CG；每组n=1700）的抑郁症患病率。对照组根据性别、年龄和保险类型与OS患者匹配。计算2009年至2015年期间性别分层的抑郁症患病率。

结果：总体而言，女性抑郁症患病率高于男性，且2009年至2015年呈上升趋势。女性OS患者与对照组的抑郁症患病率在所有分析年份均存在显著差异，例如2012年：OS组为39.4%（95%置信区间：33.4%-45.5%），CGO组为19.8%（17.6%-22.0%），CG组为15.4%（13.4%-17.4%）。男性OS患者与对照组在任何时间点均未观察到显著差异。OS术后，女性抑郁症患病率先下降，随后逐渐上升至2015年；男性OS患者的抑郁症患病率亦在术后第一年下降，后续几年呈上升趋势。两性2015年的患病率与2012年（OS手术年份）相比均无显著差异。

结论：我们发现，两性在OS术后第一年抑郁症患病率均有所下降，随后两年则呈上升趋势。OS似乎对抑郁症患病率具有短期效应，之后的上升趋势与非OS对照组的时间趋势平行。通过性别分层分析，OS患者与对照组抑郁症患病率的比较结果呈现出差异：女性在OS术前三年及术后的抑郁症患病率显著高于对照组，而男性则无此差异。术后治疗期间应实施措施，以维持OS术后抑郁症患病率的下降趋势。