Selection of Outcomes and Measurement Methods in Clinical Trials for Digital Therapeutics: Qualitative Analysis

Background: In recent years, the availability of digital therapeutic apps in medicine, digital therapeutics (DTx), has significantly increased. To evaluate the therapeutic efficacy of DTx, an increasing number of scientific studies have been conducted in this field. Several authors have pointed out that a standardized approach to DTx evaluation is relevant to improving the comparability of apps in the future. Currently, it is unclear how study authors proceed when selecting outcomes and measurement methods (O&M) for DTx studies. Objective: The primary aim of this study was to investigate how study authors currently select O&M in DTx studies, specifically for applications delivered in the form of apps. The secondary objectives were to collect suggestions for improving the comparability of DTx apps and studies in the future and to examine whether core outcome sets (COS) could represent a possible solution for enhancing comparability. Methods: This study was based on 19 semistructured interviews. All interview partners had prior experience in planning and conducting DTx studies. The interviews were conducted between August 2024 and November 2024. Subsequently, qualitative data analysis was performed according to Kuckartz and Rädiker using a deductive-inductive research approach. Results: The results of this study showed that the methodological approach for selecting O&M in DTx studies was primarily based on research, as well as on personal prior experience and individual ideas. Interview participants indicated that when selecting O&M, they particularly focused on aspects such as scientific quality criteria or practical implementation and feasibility. A suggestion for achieving better comparability of DTx studies in the future was to use standardized O&M per therapeutic indication area. Almost all interviewees considered COS to be a suitable approach for improving the comparability of DTx and associated studies. However, we also identified critical perspectives that questioned their application. Conclusions: Across professional groups, both commonalities and differences were observed in methodological approaches as well as in the selection of O&M in DTx studies. To improve the comparability of DTx interventions and trials, several approaches have been developed, for example, through the use of guidance frameworks, artificial intelligence programs, or the establishment of COS. However, further research is warranted to advance this field.