Background Depression and anxiety are highly prevalent and often co-occur. Several studies indicate the potential of disorder-specific psychological interventions for the prevention of each of these disorders. To treat comorbidity, transdiagnostic treatment concepts seem to be a promising approach, however, evidence for transdiagnostic concepts of prevention remains inconclusive. Internet- and mobile-based interventions (IMIs) may be an effective means to deliver psychological interventions on a large scale for the prevention of common mental disorders (CMDs) such as depression and anxiety. IMIs have been shown to be effective in treating CMDs, e.g. in reducing symptoms of depression and anxiety. However, there is a lack of studies examining the efficacy of interventions reducing the incidence of CMDs. Moreover, the comparative cost-effectiveness of guided versus unguided IMIs for the prevention of depression and anxiety has not been studied yet. Hence, this study aims at investigating the (cost-) effectiveness of guided and unguided internet- and mobile-based transdiagnostic individually tailored indicated prevention of depression and anxiety. Methods A multi-country three-armed randomized controlled trial will be conducted to compare a guided and unguided intervention to treatment as usual (TAU). Both active conditions are based on the same intervention, ICare Prevent, and differ only with regard to guidance format. Altogether, 954 individuals with subclinical symptoms of depression (CES-D ≥ 16) and anxiety (GAD-7 ≥ 5) who do not have a full-blown disorder will be recruited in Germany, Switzerland, Spain and the Netherlands, and randomized to one of three conditions (guided intervention, unguided intervention, or TAU). The TAU arm will receive access to the training after a 12-month waiting period. The primary outcome will be time to CMD onset (any depression/anxiety disorder) within a follow-up period of 12 months after baseline. Secondary outcomes will include disorder-specific symptom severity (depression/anxiety) assessed by diagnostic raters blinded to intervention condition at post-intervention, self-reports, acceptability, health related quality of life, and psychosocial variables associated with developing a CMD. Assessments will take place at baseline, mid-intervention (5 weeks into the intervention), post-intervention (8 weeks after randomization) and follow-up (6 and 12 months after randomization). Data will be analyzed on an intention-to-treat basis and per protocol. Cost-effectiveness will be evaluated from a public health and a societal perspective, including both direct and indirect costs. Discussion The present study will further enhance the evidence-base for transdiagnostic preventive interventions and provide valuable information about optimal trade-off between treatment outcome and costs. Trial registration German Clinical Trial Registration (DRKS - http://www.drks.de/drks_web/): DRKS00011099.

中文翻译：

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基于互联网和移动设备的引导式和非引导式跨诊断预防抑郁症和焦虑症的功效和成本效益（ICare Prevent）：在四个欧洲国家进行的一项三臂随机对照试验。

背景 抑郁和焦虑非常普遍，并且经常同时发生。一些研究表明针对特定疾病的心理干预对于预防每种疾病的潜力。为了治疗合并症，跨诊断治疗概念似乎是一种有前途的方法，然而，跨诊断预防概念的证据仍然不确定。基于互联网和移动设备的干预措施（IMIs）可能是大规模实施心理干预以预防抑郁和焦虑等常见精神障碍（CMD）的有效手段。IMI 已被证明可有效治疗 CMD，例如减轻抑郁和焦虑症状。然而，缺乏研究来检验干预措施降低 CMD 发病率的有效性。此外，引导式 IMI 与非引导式 IMI 预防抑郁和焦虑的成本效益比较尚未进行研究。因此，本研究旨在调查引导和非引导的基于互联网和移动设备的跨诊断个性化指示预防抑郁和焦虑的（成本）有效性。方法 将进行一项多国三组随机对照试验，以比较指导和非指导干预与照常治疗（TAU）。两种主动条件均基于相同的干预措施 ICare Prevent，仅在指导格式方面有所不同。总计，将在德国、瑞士、西班牙和荷兰招募 954 名患有抑郁症 (CES-D ≥ 16) 和焦虑症 (GAD-7 ≥ 5) 亚临床症状且未患有完全疾病的个体，并随机分配到三种情况之一（引导干预、非引导干预或 TAU）。TAU 部门将在 12 个月的等待期后获得培训机会。主要结局是基线后 12 个月的随访期内出现 CMD（任何抑郁/焦虑症）的时间。次要结果将包括由对干预后干预条件不知情的诊断评估者评估的疾病特异性症状严重程度（抑郁/焦虑）、自我报告、可接受性、健康相关的生活质量以及与发展 CMD 相关的心理社会变量。评估将在基线、干预中期（干预后 5 周）、干预后（随机分组后 8 周）和随访（随机分组后 6 个月和 12 个月）进行。数据将在意向治疗的基础上并按照方案进行分析。成本效益将从公共卫生和社会角度进行评估，包括直接成本和间接成本。讨论本研究将进一步增强跨诊断预防干预措施的证据基础，并提供有关治疗结果和成本之间最佳权衡的有价值的信息。试验注册 德国临床试验注册 (DRKS - http://www.drks.de/drks_web/)：DRKS00011099。