German Version of the Telehealth Usability Questionnaire and Derived Short Questionnaires for Usability and Perceived Usefulness in Health Care Assessment in Telehealth and Digital Therapeutics: Instrument Validation Study

Background: The exponential growth of telehealth is revolutionizing health care delivery, but its evaluation has not matched the pace of its uptake. Various forms of assessment, from single-item to more extensive questionnaires, have been used to assess telehealth and digital therapeutics and their usability. The most frequently used questionnaire is the "Telehealth Usability Questionnaire" (TUQ). The use of the TUQ is limited by its restricted availability in languages other than English and its feasibility. Objective: The aims of this study were to create a translated German TUQ version and to derive a short questionnaire for patients-"Telehealth Usability and Perceived Usefulness Short Questionnaire for patients" (TUUSQ). Methods: As a first step, the original 21-item TUQ was forward and back-translated twice. In the second step, 13 TUQ items were selected for their suitability for the general evaluation of telehealth on the basis of expert opinion. These 13 items were surveyed between July 2022 and September 2023 in 4 studies with patients and family members of palliative care, as well as patients with chronic autoimmune diseases, evaluating 13 health care apps, including digital therapeutics and a telehealth system (n1=128, n2=220, n3=30, and n4=12). Psychometric exploratory factor analysis was conducted. Results: The analysis revealed that a parsimonious factor structure with 2 factors ("perceived usefulness in health care" and "usability") is sufficient to describe the patient's perception. Consequently, the questionnaire could be shortened to 6 items without compromising its informativeness. Conclusions: We provide a linguistically precise German version of the TUQ for assessing the usability and perceived usefulness of telehealth. Beyond that, we supply a highly feasible shortened version that is versatile for general use in telehealth, mobile health, and digital therapeutics, which distinguishes between the 2 factors "perceived usefulness in health care" and "usability" in patients.