Supplementary Material for: Effects of a Psychological Internet Intervention in the Treatment of Mild to Moderate Depressive Symptoms: Results of the EVIDENT Study, a Randomized Controlled Trial

Background: Mild to moderate depressive symptoms are common but often remain unrecognized and treated inadequately. We hypothesized that an Internet intervention in addition to usual care is superior to care as usual alone (CAU) in the treatment of mild to moderate depressive symptoms in adults. Methods: This trial was controlled, randomized and assessor-blinded. Participants with mild to moderate depressive symptoms (Patient Health Questionnaire, PHQ-9, score 5-14) were recruited from clinical and non-clinical settings and randomized to either CAU or a 12-week Internet intervention (Deprexis) adjunctive to usual care. Outcomes were assessed at baseline, 3 months (post-assessment) and 6 months (follow-up). The primary outcome measure was self-rated depression severity (PHQ-9). The main analysis was based on the intention-to-treat principle and used linear mixed models. Results: A total of 1,013 participants were randomized. Changes in PHQ-9 from baseline differed significantly between groups (t825 = 6.12, p < 0.001 for the main effect of group). The post-assessment between-group effect size in favour of the intervention was d = 0.39 (95% CI: 0.13-0.64). It was stable at follow-up, with d = 0.32 (95% CI: 0.06-0.69). The rate of participants experiencing at least minimally clinically important PHQ-9 change at the post-assessment was higher in the intervention group (35.6 vs. 20.2%) with a number needed to treat of 7 (95% CI: 5-10). Conclusions: The Internet intervention examined in this trial was superior to CAU alone in reducing mild to moderate depressive symptoms. The magnitude of the effect is clinically important and has public health implications.

背景：轻度至中度抑郁症状十分常见，但往往难以被识别，且治疗不充分。我们提出假设：相较于常规治疗（care as usual, CAU）单独实施，在常规治疗基础上辅以互联网干预方案，可更有效地改善成人轻度至中度抑郁症状。
方法：本试验为对照、随机且设评估者盲法的临床试验。本研究从临床与非临床场景招募符合入组标准的受试者：其抑郁症状符合轻度至中度水平，即患者健康问卷（Patient Health Questionnaire, PHQ-9）得分介于5至14分之间。将受试者随机分配至常规治疗组，或接受在常规治疗基础上辅以为期12周的互联网干预方案（Deprexis）的实验组。分别于基线、3个月（治疗后评估）及6个月（随访）阶段对结局指标进行测评。主要结局指标为受试者自评的抑郁严重程度（PHQ-9得分）。主要分析基于意向性治疗原则，采用线性混合模型进行统计分析。
结果：最终共1013名受试者完成随机分组。各组受试者的PHQ-9得分较基线的变化幅度存在显著组间差异（组间主效应：t₈₂₅=6.12，p<0.001）。治疗后评估阶段，有利于干预组的组间效应量为d=0.39（95%置信区间：0.13~0.64）。该效应在随访阶段保持稳定，d=0.32（95%置信区间：0.06~0.69）。治疗后评估阶段，干预组中至少出现具有临床最小重要意义的PHQ-9得分变化的受试者占比更高（35.6% vs. 20.2%），需治疗人数为7（95%置信区间：5~10）。
结论：本试验所评估的互联网干预方案，相较于单独常规治疗，可更有效地减轻成人轻度至中度抑郁症状。该效应的强度具有重要临床意义，且具备公共卫生层面的应用价值。