Objectives: The objective was to assess the current evidence base, gathered from published systematic reviews, on the effectiveness and cost-effectiveness of digital health interventions.

Methods: To identify systematic reviews on the effectiveness of digital health technologies used for different health interventions, a literature search was conducted in the electronic database PubMed and in the literature search engine Google Scholar. Systematic reviews published in English between 2015 and 2020 and available as full text were included. The current state of studies on effectiveness and cost-effectiveness regarding digital health interventions, study designs used, intervention types, control groups and outcomes were extracted. Subsequently, extracted data were qualitatively summarized.

Results: Seventeen systematic reviews were identified for the assessment; there were a total of 585 studies among these reviews. Digital health interventions have been used in a variety of indications, including obesity, diabetes and hypertension, mental and psychological health, oncology, pulmonology, and cardiovascular disease. Some of the included systematic reviews showed positive effects, others no effects or negative effects so that no consistent conclusions could be drawn. The inconsistent results can be attributed to several factors, including differences in study design, study conduct, study duration, and intervention/treatment. Overall, results on the effectiveness of digital health technologies were partially inconsistent and varied widely in study design.

Conclusion: The evidence base was generally weak, as reported in the systematic reviews, mainly due to lack of rigor and heterogeneity in study designs. The main challenge in evaluating digital health interventions will be to use appropriate and consistent study designs.