Chatsatrian, MagdaliniMagdaliniChatsatrianKunde, KatharinaKatharinaKundeBosompem, JenniferJenniferBosompemDieris-Hirche, JanJanDieris-HircheTimmesfeld, NinaNinaTimmesfeldWirth, RainerRainerWirthJuckel, GeorgGeorgJuckelPape, MagdalenaMagdalenaPape0000-0003-1952-8625Mai, AnnaAnnaMaiGiehl, ChantalChantalGiehlUeberberg, BiancaBiancaUeberbergVollmar, Horst ChristianHorst ChristianVollmarOtte, Ina CarolaIna CarolaOtteBusse, Theresa SophieTheresa SophieBusse2026-05-052026-05-0520252292-9495https://fis.uni-bamberg.de/handle/uniba/114960Background: Digital health applications (DiGA) have been integrated into Germany’s health care system since 2019, offering certified medical devices for various health conditions. This study focuses on deprexis and Selfapy, the first 2 permanently approved DiGA for depressive disorders in Germany, to evaluate their usability for people ≥60 years. The study’s significance is underscored by the underrepresentation of older people in previous DiGA studies, accompanied by an emergent risk of inequalities in distribution for this vulnerable population. Objective: This study assessed the usability of DiGA deprexis and Selfapy for adults aged ≥60 years with mild to moderate depression. The more user-friendly option will be chosen for the DiGA4Aged project’s upcoming randomized controlled trial. Methods: The prospective observational study uses the People at the Centre of Mobile Application Development (PACMAD) usability model in a mixed methods design. The study’s multistage data collection encompasses sociodemographic data and quantitative questionnaires about health literacy (European Health Literacy Survey Questionnaire [HLS-EU-Q16]), electronic health literacy (revised German eHealth Literacy Scale [GR-eHEALS]), media affinity, depressive symptoms (9-item Patient Health Questionnaire [PHQ-9]), and perceived usability (System Usability Scale [SUS]), as well as a qualitative think-aloud and semistructured interview. Participants were equally allocated to use either deprexis or Selfapy. Recruitment of 18 participants was conducted at 3 hospital departments (ie, psychiatry, psychosomatics, and geriatrics) in spring 2024. Participants were eligible if they were aged ≥60 years, were diagnosed with mild or moderate depressive disorder, owned a digital device, and gave written consent to participate. Results: Quantitative analysis revealed age, gender, depressive severity, and health literacy parity between both groups. Selfapy users displayed marginally lower technical proficiency and lower usability scores. Qualitative data showed lower usability among participants in the Selfapy group due to design-related errors and higher cognitive load. Despite visual, psychomotor, and cognitive challenges, participants endorsed both DiGA for older users, stressing the importance of assistance and practicing the usage. Conclusions: Reported difficulties in usability may help to improve future DiGA development for older people, especially as the willingness to use DiGA exists.engdepressiondepressiveusabilitydigital healtheHEALShealth literacymHealthmobile healthmental healthappapplicationsgerontologygeriatricoldolderelderelderlyagingagedarticle10.2196/66271