Supplementary Material for: Efficacy and Moderators of Internet-Based Interventions in Adults with Subthreshold Depression: An Individual Participant Data Meta-Analysis of Randomized Controlled Trials

Introduction: Evidence on effects of Internet-based interventions to treat subthreshold depression (sD) and prevent the onset of major depression (MDD) is inconsistent. Objective: We conducted an individual participant data meta-analysis to determine differences between intervention and control groups (IG, CG) in depressive symptom severity (DSS), treatment response, close to symptom-free status, symptom deterioration and MDD onset as well as moderators of intervention outcomes. Methods: Randomized controlled trials were identified through systematic searches via PubMed, PsycINFO, Embase and Cochrane Library. Multilevel regression analyses were used to examine efficacy and moderators. Results: Seven trials (2,186 participants) were included. The IG was superior in DSS at all measurement points (posttreatment: 6–12 weeks; Hedges’ g = 0.39 [95% CI: 0.25–0.53]; follow-up 1: 3–6 months; g = 0.30 [95% CI: 0.15–0.45]; follow-up 2: 12 months, g = 0.27 [95% CI: 0.07–0.47], compared with the CG. Significantly more participants in the IG than in the CG reached response and close to symptom-free status at all measurement points. A significant difference in symptom deterioration between the groups was found at the posttreatment assessment and follow-up 2. Incidence rates for MDD onset within 12 months were lower in the IG (19%) than in the CG (26%). Higher initial DSS and older age were identified as moderators of intervention effect on DSS. Conclusions: Our findings provide evidence for Internet-based interventions to be a suitable low-threshold intervention to treat individuals with sD and to reduce the incidence of MDD. This might be particularly true for older people with a substantial symptom burden.引言：现有关于基于互联网的干预措施用于治疗阈下抑郁（subthreshold depression, sD）并预防重性抑郁障碍（major depressive disorder, MDD）发病的相关证据尚存分歧。 研究目的：本研究开展个体参与者数据元分析，旨在比较干预组（intervention group, IG）与对照组（control group, CG）在抑郁症状严重程度（depressive symptom severity, DSS）、治疗应答率、接近无症状状态、症状恶化情况、MDD发病风险以及干预效果调节变量方面的差异。 研究方法：通过PubMed、PsycINFO、Embase及Cochrane图书馆进行系统检索以筛选随机对照试验，采用多层回归分析检验干预效果及调节变量。 研究结果：最终纳入7项试验，共2186名参与者。与对照组相比，干预组在各评估时间点的DSS均更优：治疗后（6~12周）：Hedges' g=0.39，95%置信区间（CI）为0.25~0.53；首次随访（3~6个月）：g=0.30，95%CI为0.15~0.45；二次随访（12个月）：g=0.27，95%CI为0.07~0.47。在各评估时间点，干预组达到治疗应答及接近无症状状态的参与者比例均显著高于对照组。两组在治疗后评估及二次随访时的症状恶化情况存在显著差异。干预组12个月内MDD发病发生率（19%）低于对照组（26%）。研究发现，较高的基线DSS及高龄为干预对DSS的影响起到调节作用。 研究结论：本研究结果证实，基于互联网的干预措施可作为适用于阈下抑郁患者的低门槛治疗手段，同时可降低MDD的发病风险，对于症状负荷较重的老年群体而言该效果尤为显著。