Effectiveness of Guided Internet-based Interventions in the Indicated Prevention of Depression in Green Professions (PROD-A): Results of a Pragmatic Randomized Controlled Trial

Background: Major Depressive Disorder (MDD) has a major impact on public health. Reduction of depression burden in general population is of greatest importance and might be achieved by implementation of depression prevention measures into routine care. We evaluate an online prevention measure as part of a national project aiming to reduce depression in the occupational group of green professions.

Methods: This two-armed pragmatic RCT (n = 360) evaluates the effectiveness of a tailored internet-based intervention (IMI) program compared to enhanced treatment as usual. The IMI program entailed access to one of six guided IMIs each focusing on different symptom areas (depressive mood with optional comorbid diabetes, perceived stress, insomnia, panic and agoraphobia and harmful alcohol consumption). Eligible were entrepreneurs, spouses, family members and pensioners in green professions with adequate insurance status and at least subthreshold depression (PHQ≥5). Primary outcome was depressive symptom severity (QIDS-SR16) at 9-weeks post-treatment (T1). Various secondary outcomes were assessed at T1.

Results: A small effect of depression reduction (d=-0.28, 95%-CI: -0.50 to -0.07) was found at T1 favouring the IMI program (β=-0.22, 95%-CI: -0.41 to -0.02, p=.033). Categorical analysis indicated a reduced risk of potential MDD with NNTB=28.11. Adherence to the IMI program at T1 was exceptionally low.

Limitations: Results are limited to green professions and representativeness might be restricted by self-selection of participants.

Conclusion: Depression burden in green professions can be reduced by this online prevention measure. Yet, short-term effectiveness is restricted by low adherence rates.

Trial Registration: German Clinical Trial Registration: DRKS00014000. Registered: 09 April 2018.