Worldwide, the population of people aged 60 years and older is growing at a faster rate than any other age group [1]. This shift is referred to as population aging, a demographic phenomenon characterized by an increasing number of people aged 60 years and older, followed by a simultaneous decline in the younger population [2]. It is driven by increased life expectancy, with the global population aged 60 years or older expected to reach 2.1 billion by 2050 [3,4]. Although this initially emerged in high-income countries, it has now become an issue in many developing countries as well [2]. As people age, they face a range of health-related and social challenges. Older adults’ quality of life is strongly influenced by access to health care, social inclusion, availability of caregivers, and opportunities for meaningful engagement in communities they are part of [5]. Additionally, older adults are at a higher risk of experiencing different health conditions, which include cognitive impairment, chronic pain, and noncommunicable diseases such as cardiovascular diseases, diabetes mellitus, and cancer [3,6]. Therefore, the promotion of health and well-being among older adults becomes a priority for achieving healthy aging [7]. Addressing the health needs of the aging population is a pressing public health priority, especially given the increasing health care costs associated with aging [8].

The focus of this work is on digital health interventions (DHIs), which refer to the use of digital technologies to deliver health-related services, information, or support. The main aim of DHIs is to improve health outcomes, health care delivery, and health system efficiency. DHIs present innovative, cost-effective solutions to address the health-related and social challenges older adults face. DHIs have the potential to empower older adults to actively engage in their health management by promoting early detection of conditions, prevention, and personalized care [9]. The World Health Organization classifies DHIs into various categories based on their role within the health care system [10]. One category is the DHIs for personal health tracking, which includes mobile health apps (mHealth apps), phone-based sensors, wearables, and web-based platforms. These DHIs enable users to monitor their vital signs, levels of physical activity, medication adherence, and other health-related data. Emerging evidence indicates that older adults are becoming increasingly interested in digital technologies, and DHIs can be effective for them [11]. However, the success of these interventions depends on their accessibility and usability, which must be tailored to meet the needs of older adults. This can be achieved by the implementation of an inclusive design approach [12].

Inclusive design is an approach that aims to accommodate the needs of a broad spectrum of users, considering factors such as socioeconomic status, gender, age, ethnicity, and language diversity [13]. This approach is particularly important when designing for older adults, as there is no “typical” older person. Aging is an individualized process, which is shaped by both physical and social environments that influence individuals’ health behaviors and needs [4]. Consequently, DHIs must be inclusively designed to address the wide range of needs of this heterogeneous user group. DHIs that do not take into account the unique needs and abilities of older adults are likely to fail in their ability to support use and adoption by a large and growing segment of the population [14].

Several checklists and guidelines have already been developed in the field of inclusive design for DHIs targeting older adults. Much of the existing research has concentrated on mHealth apps [15-17]. For instance, Paez et al [17] investigated the usability challenges older adults face when using mobile apps and formulated a primary set of recommendations based on their findings. Similarly, Liu et al [16] proposed a set of recommendations and identified five persuasive design elements that enhance interfaces for older adult users, which include reminders, social features, gamification, personalized interventions, and health education. However, their focus remained limited to visual aspects of mobile interfaces, excluding broader DHI categories and inclusive design aspects. Gomez-Hernandez et al [15] used a scoping review methodology and proposed a guideline for the design of mobile apps for older adults that do not specifically target health. One checklist was developed in the Got-IT (Guidelines on Target Assessment for Innovative Therapeutics) project, which aimed to assist the design of inclusive digital health solutions targeting the promotion of healthy lifestyles among older adults [18], also mostly focusing on the presence and design of usable interfaces. Innovative work in this field was conducted by Boot et al [14], who aimed to understand the full range of needs of older adults and proposed comprehensive design recommendations, published in book format. Furthermore, Brewer [19] assessed the accessibility of nonvisual technologies, thereby advancing the field of inclusive design for individuals with visual impairments.

In contrast to previous contributions in this area, we aim to explore a broader range of DHIs for personal health tracking that target different health domains and address different types of age-related impairments, such as cognitive, hearing, and visual impairments. We focus on DHIs that have been co-designed with a target user group and evaluated to reflect design elements that are well perceived by older adults. Furthermore, our review considers nonvisual DHIs, such as voice assistants, which are particularly relevant for older adults with visual impairments. In addition, we aim to examine DHIs from different parts of the world to consider the social, economic, linguistic, and cultural aspects that play an important role in inclusive design.

This scoping review is part of a 3-phase development process of inclusive design heuristics of DHIs for older adults. The entire process is based on the methodology for developing usability and UX (user experience) heuristics proposed by Quiñones et al [20], which consists of (1) a knowledge generation phase, (2) formulation of heuristics, and (3) an iterative validation and improvement of heuristics. We conducted the scoping review along with expert interviews and a workshop with older adults during the knowledge generation phase to gather the knowledge necessary for developing the heuristics. This paper focuses on the scoping review of the design and development process of DHIs that specifically target older adult users. From studies, we aimed to gain insights that inform the inclusive design of DHIs, considering the diverse requirements and needs of older adults. Finally, we aggregated the collected information and proposed an initial set of design heuristics. We define heuristics as the design aspects (eg, interface design, accessibility, and personalization) and recommended design elements (eg, providing an audio content option for users with visual impairment), which promote the inclusive design of DHIs. We defined the following research questions to guide this review: (1) What are the key principles of inclusive design applied to DHIs for older adults? (2) How do current DHIs address the specific needs of older adults, including cognitive, sensory, and motor impairments? (3) What heuristics have been proposed in the literature for designing user-friendly DHIs for older adults? and (4) What best practices for inclusive design have been validated or proven effective for DHIs targeting older adults?

Given the complexity of the topic, a scoping review methodology was selected to systematically explore relevant papers that described the design of the DHIs for older adults [21]. The inclusion and exclusion criteria for selecting the papers are summarized in Textbox 1. PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guideline [22] and PRISMA-S (Preferred Reporting Items for Systematic Reviews and Meta-Analyses literature search extension) checklist [23] were followed to ensure methodological rigor and accuracy of the results. The completed PRISMA-ScR checklist is provided in Multimedia Appendix 1. The PRISMA-S checklist can be found in Multimedia Appendix 2. The review methodology was not registered in advance.

We searched three relevant databases for this topic: IEEE Xplore, Scopus, and PubMed. All database searches were initially conducted on January 12, 2025, and were rerun on September 22, 2025, using the same search strategy to identify newly published studies. Each database was searched via its web interface, and searches were run separately in each database rather than simultaneously on a single platform. No study registers were searched. No additional online sources (eg, websites, conference proceedings, and journal tables of contents) were searched to identify eligible studies, and citation searching was not undertaken for the additional study selection. We did not seek additional sources by contacting researchers, nor did we use any other search methods beyond those described above to identify further relevant studies for this scoping review. From our research questions, we retrieved the three keywords: “DHI,” “older adults,” and “inclusive.” These were used to develop the search string. The final search string was as follows: “(“digital health” OR “eHealth” OR “mHealth” OR “telemedicine” OR “telehealth” OR “digital healthcare tools” OR “digital therapeutics” OR “mobile health apps” OR “online health platforms” OR “wearables”) AND (“aging population” OR “older adults” OR “seniors” OR “aged individuals” OR “older persons” OR “geriatric population” OR “aging individuals” OR “aging adults” OR “senior citizens” OR “elderly population”) AND (“inclusive” OR “accessible” OR “equitable” OR “universal design” OR “user-friendly” OR “culturally sensitive” OR “inclusive design” OR “barrier-free” OR “non-biased” OR “non-discriminatory” OR “diverse” OR “adaptive” OR “tailored for all”).” To keep the search broad, this search strategy was applied to the title and abstract fields in each database. We did not use any previously published or validated search filters. All search strategies were developed specifically for this scoping review and were not formally peer reviewed by an independent expert before execution. The reproducible search strategies for all databases are provided in Multimedia Appendix 3.

A total of 1284 papers were found. Duplicate papers (n=508) were removed before the screening process. Papers (n=1276) were screened independently by authors (KD, LC, and CP) who examined the title and abstract of the papers to determine if they met the initial eligibility criteria (Textbox 1). The screening was carried out in the Rayyan software to facilitate the screening and deduplication process [24]. We did not perform a critical appraisal of the included sources of evidence because many studies used experience-based methods that do not fit within the critical appraisal checklist, such as prototype usability research, digital tool use evaluation, and similar experience-based approaches.

Before the analysis of the papers, all authors were given one paper to perform the initial extraction and to agree on the data extraction items and eligibility criteria. In addition, a quality assurance meeting was organized by the three authors (KD, LC, and CP) who performed the data extraction to agree on the data items to be extracted and to check that the items were understood in the same way by all authors. The final list of data items that were extracted is documented in Textbox 2. All data collected were documented in a data extraction spreadsheet.

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we performed a narrative synthesis of the results and presented the results in a descriptive manner or in tables. The extracted free text was aggregated by a thematic analysis conducted by one author (KD). She reviewed all entries for one item and identified common themes. Additionally, a locally run language model (Llama3; Meta) was used to confirm the identified themes. The prompt used was: “Conduct a thematic analysis on the following information extracted on [item]. Provide the identified themes.” A second author (LC) checked the aggregated themes for completeness and correctness.

The literature search yielded 1276 unique records that were screened at the title and abstract phase. A total of 149 papers were screened at the full-text stage, and a total of 40 papers were included and considered for information extraction (Figure 1). Papers were excluded because of the wrong age group, insufficient information on the design process and inclusive design elements of the DHI, or the wrong type of publication. An overview of the most important insights from the extracted studies is shown in Table 1. In this table summary, we included the studies that described the applied design elements aimed at making the DHI more inclusive for older adult users. Details on the extracted data are summarized in the next sections. The detailed data extraction spreadsheet and information on the exclusion reasons are provided in Multimedia Appendix 4.

As no critical appraisal was performed, no quality ratings of the included sources of evidence are presented.

The scoping review identified 40 studies published between 2013 and 2025 that addressed the inclusive design of DHIs for older adults. The temporal distribution demonstrates a marked increase in recent years, with 18 (45%) studies published in 2024-2025 alone, reflecting growing research interest in this domain. The publication trend shows modest activity from 2013-2022 (1-4 studies per year), followed by acceleration from 2023 onward (6-12 studies per year).

The included studies predominantly targeted older adults aged 60+ and 65+ years, with 23 different age group specifications identified across the corpus. Two papers [27,28] mentioned only an average age instead of an age range.

The DHIs addressed some specific medical conditions or aimed to address age-specific conditions and prevention of age-specific conditions in general: frailty [25,40], prevention [26], hip fracture, fall prevention [31,35], chronic obstructive pulmonary disease [32,55], chronic illness [33,48], mild cognitive impairment [47,56], kidney failure [37], heart failure [41], age-related conditions [42], underactivity [57], melanoma [48], and depression [58]. Eighteen papers did not mention any medical condition or symptoms on which the solution centered. Partially, they mentioned health aspects they focused on, such as physical activity. The following specific disabilities were considered in the design of the solutions by 6 papers: Functional disabilities [28], cognitive impairment [47,56], sensory decline [38], blindness or low vision [59], or hearing impairment [60]. Overall, 34/40 (85%) papers reported a study with their DHI ranging from a requirements collection study to qualitative and quantitative cocreational studies, to a feasibility study, and clinical trials.

Only 3 papers defined inclusive design. Khamaj et al [37] define inclusive design in a way that “users’ physical capabilities are considered, and the software is made accessible and flexible to accommodate a variety of mobility or dexterity challenges, especially those that affect older persons.” Wikberg-Nilsson et al [38] refer to a publication and define inclusive design as “an approach not comprising a set of fixed criteria but emphasizing the design practice responsibility of embracing users with various special needs [61,62].” Chopvitayakun et al [53] use the term “user sensitive inclusive design,” which refers to the expansion of user-centered design principles that explicitly address the diverse requirements of older adult individuals and those with disabilities [63].

The DHIs reported in the papers can be grouped into 5 categories as shown in Textbox 3. Mobile apps (ie, installed apps) included apps for supporting health promotion and education (eg, a physical activity promotion app) [37,43,49,52,54,57,64,65], for self-care and chronic condition management (eg, an app for frailty follow-up) [34,40,41,60], for rehabilitation and recovery (eg, an app for rehabilitation exercises) [30,46], for balance and physical functioning testing (eg, a self-test for leg strength and balance) [31], for self-management [35,50,55], and for nutrition calculation [53]. Web-based platforms and web apps are DHIs accessed via a web browser. Symptom checkers [66], conversational agents [32], and a self-screening and monitoring platform [29] were provided as a web-based platform, to mention a few examples. Voice and virtual assistant technology tools use speech and artificial intelligence interfaces to assist in remote care. Telehealth and remote monitoring systems include smart home sensors with telehealth [48] or smart health care systems for biomedical data collection [44]. Tablet-based and specialized systems include a video feedback tool [33], a telemedicine-based exercise program [47], tablet-based drawing and dragging tasks [56], a sensor-based system for monitoring and management of health and mobility [54], and an augmented reality–based system that provides support for older adults in hospital visits [50]. Use of wearable technologies was not identified.

Figure 2 shows the gap analysis between medical conditions and technologies. Mobile apps dominate, followed by web-based platforms. Tablet-based and specialized systems, voice and virtual assistants, smart home sensors and telehealth or telemonitoring, and augmented reality technologies are underrepresented across all health domains.

Further, 28 papers did not provide information on the parties involved in the development of the DHIs (the DHIs’ primary users). Other groups were involved in DHI development, including (1) family and informal caregivers [42,47], (2) health care professionals (clinicians, geriatricians, cardiologists, nurses, physiotherapists, dieticians, occupational therapists, social workers, and mental health professionals) [50], (3) design and development teams (app developers, software engineers, UX researchers, and service designers) [28,31,42], (4) research and academics (interdisciplinary teams including sport scientists, sociologists, and university researchers) [40,43,56], and (5) other community stakeholders (community care professionals, community agencies, and aging service providers) [40,48,58]

The studies included in this scoping review used a variety of participatory and user-centered design methods to involve older adults in the design, development, and evaluation of DHI. Interviews and questionnaires, usability testing, focus groups, cocreation and participatory workshops, observational methods, mixed methods, and iterative feedback loops were featured in at least one study.

Semistructured and structured interviews [23,28-31,38-40,42-45,49,59,60,63,65,66] were used to elicit user requirements, explore experiences, and assess system usability. Structured questionnaires were also used to collect quantitative data on usability [56], user confidence [41], system acceptance [37,47], or user sentiment and requirement specification [55]. Natural language processing and sentiment analysis were used to further analyze the interview data [64].

Usability testing was conducted in various formats, including (1) think-aloud protocols during interaction with prototypes [31,42,66]; (2) task-based evaluations with mock-ups [55]; (3) structured usability surveys [26,37,49,53,58]; and (4) feasibility and acceptability tests to assess system functionality, ease of use, and user satisfaction, often occurring iteratively across different development stages [41,47,57].

Focus groups were used to gather group-level perspectives on needs, expectations, and experiences [30,31,34]. These sessions often informed requirements gathering and usability evaluation. Focus groups were sometimes combined with other methods, such as interviews or surveys, to gain a comprehensive understanding of user input [38-40,52,55].

Cocreational and participatory workshops were used to involve older adults in the design process, including (1) hands-on interaction with prototypes [29,31]; (2) group discussions and design exercises [32,38]; (3) interdisciplinary input from researchers, clinicians, and engineers [33,40]; and (4) community-based workshops and symposia [56].

Observational methods, often conducted in home or community settings, provided real-time insights into how older adults interacted with digital tools [36,39,66]. Interviews, scenario-based exercises, and mixed methods combining qualitative and quantitative techniques [49,50,56] enabled comprehensive evaluation through iterative cycles of design, testing, and refinement. Feedback was gathered through surveys, interviews, usability testing, and cocreation sessions.

A total of 26 papers referred to user-centered design frameworks, digital and usability frameworks, health and behavioral science frameworks, cocreation guidelines and processes, health-specific and inclusive design guidelines, and study-specific conceptual models used in DHI design and development. Most of the frameworks were mentioned only in one of the papers, as shown in Textbox 4.

A gap analysis of methodological approaches and frameworks (Figure 3) shows that, although usability testing is often guided by user- and human-centered design principles, it is frequently conducted without reference to any specific framework. Occasionally, usability testing is integrated with health or behavioral frameworks. Cocreation guidelines are referenced only when cocreation methods are explicitly used, and even then, inconsistently. Digital and usability frameworks are usually used during cocreation workshops. Notable gaps include the limited application of user- and human-centered design frameworks in focus groups and the rare integration of digital or usability frameworks with usability testing. Health-specific and inclusive design guidelines are occasionally used alongside focus groups, interviews, and usability testing, but not in workshop settings. Overall, frameworks are rarely mentioned in the included papers (“not specified”).

Eleven categories of design elements were identified in the included papers: visual design and readability, navigation, accessibility, customization and personalization, social engagement and support, learnability and educational content, multiplatforms and device compatibility, motivation, feedback and user engagement, security and privacy, and inclusive language and costs (Figure 4). Textbox 5 provides more details on the recommended design elements per design aspect. Figure 4 summarizes them in a visual manner.

The papers reviewed mentioned several barriers to the effective adoption and sustained use of DHIs by older adults. These barriers were grouped into the following thematic categories: technical barriers; usability and design challenges; cognitive, physical, and sensory limitations; psychological and motivational barriers; social and cultural barriers; systemic and structural barriers; and engagement and feedback-related issues.

Older adults encountered several technical barriers that limited their engagement with digital health tools. First, of device compatibility and access, some lacked access to adequate devices (eg, those capable of videoconferencing [26,27] or voice interaction). Others found smartphones and tablets incompatible or difficult to use due to user interface or UX issues [51]. Second, of connectivity and power, poor network connections, power instability, and internet access issues were common, especially in rural or underserved areas [26]. Third, of software issues, inaccurate voice recognition, unresponsive apps, software bugs, and unintuitive interfaces caused frustration and dropouts [26]. Finally, of touchscreen and input difficulties, challenges with touch screens, scroll menus, and small icons were especially problematic for those with arthritis or limited finger dexterity [34].

Usability and design challenges resulted from complex user interfaces (eg, unclear labeling and confusing navigation paths) [34]. Logging in, entering passwords, registering accounts, and verifying identities were commonly cited barriers. Lack of tailored content, unclear task instructions, and irrelevant app features diminished user engagement. Font sizes, colors, and interface elements often failed to meet accessibility standards for aging populations [42].

Age-related health issues, such as memory issues, difficulties in following instructions, or inability to achieve basic digital literacy [46], hampered DHI use. Sensory impairments such as poor vision, hearing loss, or reduced motor function made interaction difficult [38], as did physical impairments such as holding devices, prolonged screen time, or discomfort with extended DHI use.

Some papers described varying degrees of resistance toward adopting new technology among older adults. Fear of making mistakes, not trusting the technology, and worrying about fraud contributed to the reluctance [42]. Some older adults did not see the added value of DHIs, especially when alternatives such as caregiver support were available. Even with manuals and support, older adults were sometimes unwilling to learn due to perceived difficulty.

Social and cultural barriers also played a significant role in DHI acceptance, as well as in older adults’ involvement in design and development. Stereotypes that portray older adults as incapable [35], language barriers, and culturally irrelevant design affecting usability and confidence discouraged older adults’ involvement in DHI design and development.

At the organizational and infrastructure level, affordability of devices, subscriptions, or internet plans was a major concern for adoption [37]. Lack of professional prescribing of digital tools, poor promotion of assistive technologies, and limited access to services were cited as barriers to uptake. Privacy concerns, unclear ownership of personal health data, and lack of regulatory oversight contribute to limited trust in the DHIs [36].

The lack of real-time response and human support reduced the perceived value of the technology. Missing or poorly designed motivational elements, infrequent or poorly timed reminders, intrusive voice messages, and irrelevant prompts hindered habit formation [48]. Without habit formation, the older adults simply forgot to use the system.

The aspects that were extracted as facilitators represent the opposite of the barriers and concern individual factors, technological design factors, and social and behavioral support factors. They can be grouped into 6 categories and are summarized in Textbox 6.

A primary objective of this work was to identify a set of principles for the inclusive design of DHIs for use by adults aged 60 years and older. Only 3 papers explicitly defined inclusive design, highlighting conceptual inconsistencies across the literature. Khamaj and Ali [37] emphasized accessibility and flexibility for users with mobility or dexterity challenges, while Wikberg-Nilsson et al [38] framed it as a design responsibility to include users with diverse needs. Chopvitayakun et al [53] introduced “user-sensitive inclusive design,” extending user-centered design to older adults and people with disabilities. To integrate these views, we adapt the definition presented in the introduction accordingly: inclusive design is an approach that aims to accommodate the needs of a broad spectrum of users by proactively considering variations in physical, cognitive, and social capabilities, as well as factors such as socioeconomic status, gender, age, ethnicity, and language diversity.

A comparison of the 11 derived design elements (design guidelines) with established frameworks, such as Nielsen’s usability heuristics and the Universal Design Principles (Table 2), reveals areas of alignment as well as extensions relevant to DHIs for aging populations. Our guidelines share fundamental aspects with existing frameworks, such as visual clarity, navigational consistency, and feedback mechanisms, all of which support usability and accessibility. However, they also encompass psychosocial and contextual dimensions that are critical for older adults, extending beyond traditional usability. Specifically, the inclusion of social engagement, motivational design, and cost considerations introduces equity and sustainability aspects that are underrepresented in the classical usability and accessibility models. Similarly, features such as personalization, multiplatform compatibility, and inclusive language adapt established principles to the heterogeneity of older users' abilities, preferences, and resources. This synthesis shows that, while established heuristics and guidelines provide a baseline for functional usability heuristics, inclusive design specifically targeting older adults places usability within a broader framework of social participation, trust, and empowerment—key factors in sustaining engagement and efficacy in DHIs for older adults.

This scoping review synthesized evidence from 40 studies on inclusive design of DHI for older adults, revealing both progress and persistent gaps in this emerging field. Three key findings merit particular attention: (1) the recent growth in research activity suggests increasing recognition of the importance of inclusive design for aging populations; (2) despite this growth, substantial evidence gaps persist across DHI types, health domains, and methodological approaches; and (3) there remains a concerning disconnect between stated inclusive design objectives and actual implementation of inclusive design principles.

The predominance of mobile apps is both logical and limiting. While smartphones offer portability, sensors, and always-available functionality suitable for health monitoring and behavior change interventions, the mobile-first approach may inadvertently exclude older adults with limited smartphone access or a preference for larger screens. The minimal representation of web platforms is particularly concerning, given that many older adults report greater comfort with computer-based interfaces and that websites can be more easily accessed across devices without requiring app installation skills.

The research studies included in this analysis were developed to facilitate DHI use among people with a wide range of common physical disabilities, including vision impairments, hearing impairments, and sensory decline, as well as mild cognitive impairment. In some instances, co-design participants had lived experience of a particular health condition or physical limitation, while in other initiatives, a cohort of older adults with no specific pre-existing conditions provided user feedback. Future research could involve older adults with age-specific disabilities in more depth to cover these aspects in DHI design to a larger extent.

Furthermore, the initiatives described in the studies were designed to fulfill common health-related goals, for example, prevent falls, increase physical activity, and address depression. As these goals are common to older adults all over the world, it is possible to infer that the principles identified can be generalized to many locations and clinical settings. The inclusion of individuals with a diverse range of functional challenges suggests that the learnings from this study will be generally applicable to community-dwelling older adults. However, our analysis also indicates that inclusive design has not been applied to certain age-related medical conditions within the reviewed literature, notably diabetes, pain management, medication adherence, and social isolation.

The studies included in this analysis involved the co-design of 5 types of DHIs: mobile apps (20 studies), web-based platforms and web apps (6 studies), tablet-based and specialized systems (8 studies), telehealth and remote monitoring systems (4 studies), and voice and virtual assistants (2 studies), as noted in Table 2. As a result, all major categories of DHIs currently in use as nonexperimental tools are represented in the analysis. The preponderance of work involving mHealth apps is unsurprising given the maturity and broad acceptance of mobile technology and its usability across community and care settings. The inclusion of work on specialized systems, telehealth applications, and remote monitoring systems broadened the experience captured beyond the mHealth and tablet device sector, ensuring that this analysis is relevant beyond mHealth design. Research on inclusive design considering other technologies is needed (eg, voice and virtual assistants, tablet-based systems, smart home sensors, and wearables).

Similarly, the design heuristics identified in the studies included in the preset analysis (Textbox 4) encompass a broad range of design aspects grounded in human-centered design, web accessibility guidelines, interface usability, digital UX, and the biology of aging. Distributed among 11 design aspects, the recommended inclusive design elements provide broad, deep guidance for design and co-design of DHIs to be used by older adults. Some elements (eg, apply large-sized fonts and design for different cognitive abilities) are so well-understood as to seem like common sense, while other elements (eg, enable interaction with avatars during the learning process) historically have been less used. This collection of design aspects forms a repository of best practices for design for older adults as well as for other groups (eg, people with disabilities and digital interactions in patients’ nonpreferred languages) and points out opportunities for additional research into inclusive design.

A particular value of the present work is its identification of design elements that facilitate the adoption of DHIs by older adults. The most carefully planned development effort is of no consequence if the intended population is unable or unwilling to integrate the DHI into daily life in real-world settings. The 6 categories of facilitators—personal motivation and attitudes, usability and accessibility, personalization and relevance, social support and interaction, functionalities and health benefits, and engagement strategies—offer a comprehensive view of personal and situational factors underlying DHI adoption. This analysis may be particularly valuable in resource-constrained environments in which inclusive design efforts must be tightly focused on filling specific gaps.

Personalization emerged as both a frequent design principle and a top facilitator to adoption, yet this creates tension with the principle of simplicity. Offering personalization requires users to understand what can be customized, navigate to customization settings, make informed decisions about preferences, and potentially manage increased complexity. Balancing personalization with simplicity requires sophisticated design that provides sensible defaults, progressive disclosure of advanced features, and clear guidance—challenges that few studies explicitly addressed so far and remain open for future studies.

The co-design efforts included in the present analysis were developed in response to perceived community needs and, in many cases, were designed around available resources within the given setting. This circumstance created significant variation among the study designs and resulted in an abundance of real-world experience that supports the generalizability of the learnings. The variability of the older adult co-design participants, the methods used to elicit feedback, and the range of health promotion objectives among the individual studies surfaced neither universal design principles for the older adult population nor effective co-design strategies for this group. Rather, this study identifies a range of ways to co-design DHIs and provides insight into the types of learning that may be realized through these approaches.

While some studies adapted existing frameworks or developed new ones specifically for older adults, the overall application of design frameworks remains limited. This may be due to the scarcity of frameworks explicitly tailored to DHIs for this population, as well as the persistent gap between theoretical models and their practical implementation. Existing frameworks frequently emphasize specific dimensions, such as usability or UX, rather than addressing the broader context of use. However, the design of DHIs for older adults requires consideration of the entire ecosystem into which these technologies are integrated, including all relevant contextual and interactional factors. The following practical implications highlight key aspects that warrant attention in future research and development efforts.

The resulting guidelines highlight that the inclusive design of DHI extends beyond traditional considerations of usability and user interface design. Instead, inclusive design involves addressing a multitude of dimensions that must be deliberately integrated into the design process. This underscores the growing importance of participatory design methodologies, which ensure comprehensive coverage of diverse factors influencing user engagement and the effectiveness of DHIs.

Additionally, organizational and infrastructural considerations must be rigorously documented and incorporated into design decisions. As individuals age, they often experience increased dependency and reduced flexibility in adapting to new technologies. Therefore, DHIs should proactively incorporate mechanisms such as peer support or interactions facilitated by health care professionals. These interpersonal components are essential for building trust, demonstrating the practical usefulness of the technology, and providing immediate assistance to overcome technical obstacles.

Adopting a participatory design approach [69] ensures that diverse perspectives and experiences from the target demographic are systematically gathered and used. Our proposed design guidelines offer a set of practical best practices and recommendations. However, it is important to note that designers do not need to apply each element of the guideline universally. Instead, the design must avoid a “one size fits all” philosophy, emphasizing customization and alignment with the specific needs and preferences of each unique user group targeted by the DHI.

The findings of this work have important implications for the practice of health and health care more broadly. The need to mitigate older adults’ isolation and loneliness was highlighted during the COVID-19 pandemic, when individuals worldwide were expected to remain at home for weeks to months, curtailing all routine social activity and in-person interactions with others [70]. In nonpandemic times, the common life experiences of loss of mobility, loss of vision and hearing, lack of transportation, insufficient financial resources, and others prevent older adults from accessing in-person care, necessitating eHealth solutions [71]. The range and variety of DHIs developed through co-design with older adults and the ability to create rich digital experiences with minimal reliance on validated design frameworks observed in the analysis suggest that co-design supports flexibility and tailoring of DHIs to local populations and conditions. This opportunity for customization will be key to the success of health service delivery for older adults and improved health outcomes as countries worldwide seek to address the needs of aging populations. The increase in publications on inclusive design of DHI for older adults after the COVID-19 pandemic indicates that researchers are starting to think about these aspects. However, much more research is needed, as the identified gaps show.

Furthermore, this work underscores the need for affordable, reliable internet access as well as simple, functional patient portals built for people with a range of abilities. The need for broadband access has been well-understood for years [72], but remains out of reach for many [73,74]. The digital divide is often conceptualized as a technological problem, but acceptability, adequacy, and affordability dimensions play a role as well [75]. People who live at a distance from health care facilities and must access some of their care or health-promoting services online benefit from co-design of DHIs because co-design facilitates accounting for environmental, technological, and cultural barriers from the start.

The included papers did not provide all the information that was of interest. Specifically, the development and design processes were often not well described; for example, 28 papers did not provide details on who was involved in the development process. Some papers were excluded because the digital solution was not or insufficiently described. Consequently, bias might have been added to our results. To address this limitation, we conducted in parallel expert interviews and a participatory workshop with older adults, and we will integrate the results into the set of guidelines presented here.

In addition, the definition of the term older adult was not used in a consistent manner throughout the different papers included. Sometimes, papers described the solution for older adults, but younger adults, for example, those aged 20 years, were included in the study. Those papers were excluded from our study.

Another limitation of this scoping review is that the review protocol was not registered in advance, which may reduce transparency and increase the potential for unintentional bias in the review process. To address this limitation, all three authors critically reflected on the different steps. The included papers were not assessed systematically regarding their methodological quality using tools. For this reason, we are unable to distinguish limitations of the design of DHI from reporting gaps and study quality issues of the included papers.

The guidelines presented in this paper result from a literature search. Thus, the DHI considered might be research prototypes, probably not covering the practical perspective completely.

Our findings suggest that inclusive DHI design for older adults should be considered a multidimensional process integrating psychosocial and contextual factors alongside usability and accessibility. Emphasizing social engagement, motivational features, and affordability enables designers to address equity and sustainability gaps that classical usability approaches do not adequately capture.

With these results, we contribute to our 3-phase development process of inclusive design heuristics of DHI for older adults. We proposed an initial set of inclusive design guidelines, which will be integrated with the information collected from other sources, such as expert interviews and participatory workshops with older adults, into a set of heuristics as a next step. Once this has been done, the resulting list of heuristics needs to be validated and improved. Future work could develop an evaluative checklist using the final set of heuristics that can be used in the co-design sessions of DHI with older adults or within usability testing and heuristic evaluations.