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。我们假设，在成人轻中度抑郁症状的治疗中，联合常规护理的互联网干预方案，要优于单纯常规护理（care as usual, CAU）。
方法：本试验为对照、随机且评估者设盲的临床试验。研究从临床与非临床场景招募了符合轻中度抑郁症状标准的受试者（患者健康问卷9项量表[Patient Health Questionnaire, PHQ-9]得分5~14分），将其随机分配至单纯常规护理组，或联合12周互联网干预（Deprexis）的常规护理组。分别于基线、3个月（干预后评估）及6个月（随访）对结局指标进行评估。主要结局指标为自评抑郁严重程度（PHQ-9）。主要分析基于意向性治疗原则，并采用线性混合模型进行统计。
结果：最终共1013名受试者完成随机分组。两组受试者的PHQ-9得分较基线的变化存在显著组间差异（组间主效应：t₈₂₅=6.12，P<0.001）。干预后评估的组间效应量偏向干预组，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）。干预后评估中，干预组至少达到临床最小重要变化的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，在改善成人轻中度抑郁症状方面优于单纯常规护理。该效应的临床意义显著，且具备公共卫生层面的应用价值。