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：关于基于互联网干预措施在治疗轻度抑郁（sD）和预防重度抑郁（MDD）发作方面效果的证据存在不一致性。研究目的：我们通过对个体参与者数据的荟萃分析，旨在确定干预组（IG）与控制组（CG）在抑郁症状严重程度（DSS）、治疗反应、接近无症状状态、症状恶化以及MDD发作方面的差异，以及干预效果的调节因素。研究方法：通过PubMed、PsycINFO、Embase和Cochrane Library的系统搜索识别随机对照试验。采用多层次回归分析检验疗效和调节因素。研究结果：共纳入七项试验（2,186名参与者）。在所有测量点（治疗后：6-12周；Hedges' g = 0.39 [95% CI: 0.25-0.53]；随访1：3-6个月；g = 0.30 [95% CI: 0.15-0.45]；随访2：12个月，g = 0.27 [95% CI: 0.07-0.47]），与CG相比，IG在DSS方面均表现出显著优势。在所有测量点，IG中达到反应和接近无症状态的人数显著多于CG。在治疗后评估和随访2中，两组间症状恶化存在显著差异。在12个月内MDD发作的发生率在IG（19%）中低于CG（26%）。初始DSS较高和年龄较大被确定为干预效果对DSS的调节因素。结论：我们的研究结果为基于互联网的干预措施提供了证据，表明其为治疗轻度抑郁和降低MDD发病率的一种适宜的门槛较低的干预手段。这对于症状负担较重的老年人而言，可能尤为确切。