Clinical and cost-effectiveness of guided internet-based interventions in the indicated prevention of depression in green professions (PROD-A): Study protocol of a 36-month follow-up pragmatic randomized controlled trial

Background: People in green professions are exposed to a variety of risk factors, which could possibly enhance the development of depression. Amongst possible prevention approaches, internet- and mobile-based interventions (IMIs) have been shown to be effective and scalable. However, little is known about the effectiveness in green professions. The aim of the present study is to examine the (cost-)effectiveness of a tailored IMI program for reducing depressive symptoms and preventing the onset of clinical depression compared to enhanced treatment as usual (TAU+). Methods: A pragmatic randomized controlled trial (RCT) will be conducted to evaluate a tailored and therapeutically guided preventive IMI program in comparison to TAU+ with follow-ups at post-treatment (9 weeks), 6-, 12-, 24-, and 36-months. Entrepreneurs in green professions, collaborating spouses, family members and pensioners (N = 360) with sufficient insurance status and at least subthreshold depression (PHQ-9 ≥ 5) are eligible for inclusion. Primary outcome is depressive symptom severity (QIDS-SR16). Secondary outcomes include incidence of depression (QIDS-SR16), quality of life (AQoL-8D) and negative treatment effects (INEP). A health-economic evaluation will be conducted from a societal perspective. The IMI program is provided by psychologists of an external service company and consists of six guided IMIs (6-8 modules, duration: 6-8 weeks) targeting different symptoms (depressive mood, depressive mood with comorbid diabetes, perceived stress, insomnia, panic and agoraphobic symptoms or harmful alcohol use). Intervention choice depends on a screening of participants' symptoms and individual preferences. The intervention phase is followed by a 12-months consolidating phase with monthly contact to the e-coach. Discussion: This is the first pragmatic RCT investigating long-term effectiveness of a tailored guided IMI program for depression prevention in green professions. The present trial builds on a large-scale strategy for depression prevention in green professions. The intended implementation of the IMI program with a nationwide rollout has the potential to reduce overall depression burden and associated health care costs in case of given effectiveness. Trial registration: German Clinical Trial Registration: DRKS00014000. Registered on 09 April 2018.