I. Introduction
The proportion of older adults (those aged 65 years and older) is rapidly increasing worldwide, especially in South Korea, where it is expected to exceed 40% by 2050 [
1]. Alongside this demographic shift, the prevalence of chronic diseases has risen as well; in 2020, 84.0% of older adults in South Korea were reported to have at least one chronic disease, and 54.9% were dealing with two or more chronic diseases, a situation referred to as multiple chronic conditions [
1]. The increase in the number of older adults living with multiple chronic conditions highlights the importance of self-management. While research has extensively documented the prevalence, mortality rates, and financial burdens of these diseases, the literature includes a relative lack of emphasis on providing effective support for affected individuals and populations [
2].
Aging societies, the coronavirus disease 2019 pandemic, and digital transformation have rapidly revolutionized the global healthcare system. Digital health technologies, including mobile health, telehealth, and wearable devices, are promising tools for promoting health and managing chronic diseases among older adults [
3]. Digital health technology offers a cost-effective solution that overcomes traditional barriers such as distance and time, facilitates access to healthcare, and supports self-management through behavioral changes [
4].
Despite the benefits of digital health technologies, previous studies have shown that about half of older adults discontinue using mobile health applications (apps) within 2 weeks, underscoring their limited acceptance in this demographic [
5]. Therefore, when developing apps for older adults, it is essential to prioritize usability by considering the natural changes of aging, including declines in vision, hearing, motor skills, and cognition [
6,
7]. Additionally, for effective digital health interventions, it is necessary to utilize digital health coaching strategies that comprise digital engagement, communication with healthcare providers, and human contact [
8]. Digital health coaching, which combines digital technologies with health coaching, provides personalized healthcare feedback and motivation, effectively promoting health behavior changes and improving self-management for older adults with chronic diseases [
9].
Usability is a key factor in the adoption of digital health technologies. Usability testing represents a crucial step in app development; however, it is often overlooked even in the context of the enormous recent increase in mobile health apps [
5]. Furthermore, previous research indicates a lack of comprehensive description of the development process for mobile health apps targeting older adults, indicating a need for studies to improve productivity and reduce the waste of resources and time [
10].
Accordingly, our objective was to develop an age-friendly self-management mobile application that incorporates digital health coaching strategies for older adults with multiple chronic conditions. Additionally, we evaluated the app’s usability.
II. Methods
This developmental study aimed to develop and assess the usability of a mobile application, HAHA2022, an acronym for “Happy Aging, Healthy Aging 2022.”
1. Development
The contents of the HAHA2022 app were designed based on the researcher’s previous studies [
11,
12], a needs assessment comprising a preliminary survey and focus group interviews with older adults [
13,
14], Living a Healthy Life with Chronic Conditions by Lorig [
15], and verified information from the Korea Disease Control and Prevention Agency’s National Health Information Portal and the Korea Health Promotion Institute.
The survey and interviews identified key needs for the self-management of older adults, including “communication with healthcare providers” and “information on disease management” [
13,
14]. Notable factors facilitating the adoption of digital technology included “age-friendly design,” “cost of digital devices and services,” “personal reminders,” and “shared goal-setting,” while “lack of human contact” was identified as a barrier [
13,
14].
Based on the literature review, most studies focused on disease-specific interventions, with limited emphasis on multiple chronic conditions. Mobile phones emerged as the most frequently utilized digital devices, and the predominant approach to interventions was non-contact, with hybrid delivery models rarely used. These findings highlight the need to develop and evaluate mobile-based self-management programs for older adults with multiple chronic conditions.
The HAHA2022 app was created by a multidisciplinary team that included experts in gerontological nursing and medical engineering, software developers, user interface/user experience (UI/UX) designers, and professional app programmers. Since over 90% of South Korean older adults with smartphones use the Android platform [
16], the mobile app production environment was developed for the Android operating system. The development of the HAHA2022 app utilized rapid prototyping, an iterative design approach that enables quick refinement of functionality through frequent updates and multiple short cycles [
17]. When interacting with technology, older adults often face physical challenges, such as visual, auditory, and motor coordination difficulties, as well as cognitive challenges like memory and attention decline [
18]. Consequently, mobile app development must incorporate a user-centered design. The HAHA2022 app prioritized age-friendly features to improve usability [
5]. Additionally, we created a web-based administration portal to allow the research team and app developers to monitor logs and address technological issues.
2. Evaluation (Usability Testing)
HAHA2022 was evaluated by two groups: an expert panel and a sample of older adults, who represent the application’s intended user base. In alignment with Nielsen’s findings [
19], the usability test included eight expert panel members and 10 older adults. All measurements used received approval from the original authors and the Korean translators.
1) Expert panel
The expert panel comprised eight professionals: two professors of gerontological nursing, a professor of nursing informatics, a professor of medical engineering, a nursing researcher who had developed a mobile healthcare app, a community healthcare specialist, and two nurses at a senior welfare center. The evaluation of HAHA2022 utilized the Korean version of the Mobile Application Rating Scale (MARS) [
20]. The MARS is a widely recognized tool for assessing the quality of mobile health applications, demonstrating reliability and high internal consistency (Cronbach’s alpha = 0.90) [
21]. It comprises 23 items across five quality subscales: engagement, functionality, aesthetics, information, and subjective quality. Each item is rated using a 5-point Likert scale (1, inadequate; 2, poor; 3, acceptable; 4, good; 5, excellent), with scores above 3 indicating high quality.
2) User participants
To evaluate the usability of the mobile app, convenience sampling was employed to recruit older adults from a single representative senior welfare center in Seoul, South Korea. The inclusion criteria were as follows: (1) being 65 years of age or older; (2) having no cognitive impairments that could interfere with study participation, as indicated by the Korean version of Mini-Mental State Examination score above 24; (3) having a diagnosis of two or more chronic diseases and being on at least one medication; and (4) having experience with two-way communication via smartphone-based social network services.
HAHA2022 was also assessed using a Korean translation of the user version of the MARS (uMARS) [
22]. This scale consists of 26 items across six quality subscales: engagement, functionality, aesthetics, information quality, subjective quality, and perceived impact. It has demonstrated high internal consistency, with a Cronbach’s alpha of 0.90 [
23]. Each item is rated on a 5-point Likert scale, where 1 indicates “inadequate” and 5 signifies “excellent.”
Data collection for the usability evaluation of the HAHA2022 app, designed for older adults with multiple chronic conditions, occurred in July 2022. Ten older adults, ranging in age from 65 to 79 years (90% of whom were female), used the app for 2 weeks and participated in the usability test. Participant characteristics are detailed in
Table 1. Research assistants, who were not affiliated with the study, were recruited and received training on the study’s procedures and measurements prior to data collection. Following training, they conducted in-person, one-on-one usability evaluations with the participants.
3. Ethical Consideration
This study received approval from the Institutional Review Board of Seoul National University (IRB No. 2207/003-005) and was conducted in accordance with the Declaration of Helsinki. After explaining the purpose and process of the study, we obtained written informed consent from all participants.
IV. Discussion
This study reports the development and evaluation of a mobile application designed for digital health coaching on self-management in older adults with multiple chronic conditions. The application, HAHA2022, received high usability ratings from both an expert panel and a group of older adults, suggesting that it is a well-designed and user-friendly app for older adults.
Previous research evaluating lifestyle management apps using the Korean MARS reported an average score of 3.4 [
25]. In comparison, HAHA2022 received higher average scores, at 4.20 from the expert panel and 4.37 from users. Experts and users provided similar overall scores, with users assigning slightly higher ratings. The expert panel gave the highest scores for “aesthetics,” while users rated “information” highest.
Previous research [
26] indicates that experts focus on aesthetic factors such as layout, colors, graphic design, and visual appeal when evaluating apps. This suggests that HAHA2022 was perceived as orderly, well-designed, and professional. The fact that users assigned the highest score to “information” suggests that HAHA2022 contains credible content, which may be augmented by the digital health coaching delivered via telephone call by nurse members of the research team.
In addition to these assessments, we collected qualitative feedback through open-ended questions, which allowed participants to share their thoughts on the app’s usability. For instance, some users noted occasional errors in step tracking synchronization. In response, we worked with the developers to update the system, improving the sync between the smart band and the app. Any data that were not properly collected were manually entered by the research team via the admin web page. Separately, in response to comments about video playback, we advised users of the option to enlarge the video for a more comfortable viewing experience by clicking the full-screen button. Many participants reported satisfaction with the app, describing it as user-friendly and helpful. Some even indicated that they would recommend it to friends.
Among the sub-items of uMARS evaluated by users, “target group” and “willingness to use” received the highest scores. This outcome is promising, especially considering that previous research has shown a gradual decline in technology usage among older adults regarding digital health interventions [
10]. Additionally, the expert panel awarded the highest score to “ease of use.” These findings suggest that the HAHA2022 app is well-suited for older adults, featuring age-friendly design elements such as large fonts, simplified gestures, and intuitive layouts to mitigate physical and cognitive challenges. Such design ensures that the app effectively delivers content that is realistic and engaging, accommodating the diverse levels of technological proficiency found among older adults. The results also imply that the combination of digital health coaching with age-friendly features represented an effective strategy. Usability is a key factor in the adoption of healthcare mobile apps, and it is anticipated to improve self-management and well-being in the older adult population [
5].
Despite the overall positive feedback, the low willingness-to-pay scores from experts and users indicate that the cost of digital devices and internet services represents a major barrier to technology adoption [
27]. The technology must be user-friendly, functional, and affordable. Prior research underscores the importance of considering economic factors when designing healthcare technologies for older adults, as high costs can hinder their adoption of new technologies [
28]. This also suggests the need for financing strategies; for instance, our research team provided data coupons to all participants to ensure stable internet access. Moreover, payment plans may be perceived as burdensome by older adults who do not see an immediate or clear need for these technologies [
28]. Accordingly, an alternative approach could be to more effectively communicate the long-term financial benefits of healthcare technologies to older adults. This would improve their understanding of potential savings overall and encourage their investment in managing future healthcare expenses.
The app’s influence on chronic disease self-management was markedly positive, reflected by an average score of 4.23. It includes features such as health logging, educational content, reminders, and digital health coaching strategies—such as communication, human interaction, and personalization—all of which support effective self-management in older adults. Nevertheless, further research is needed to confirm the app’s long-term effectiveness in managing multiple chronic conditions in this population. Moreover, digital health coaching is resource-intensive, posing challenges to scalability. This obstacle may be overcome by thoughtfully incorporating advanced technologies such as artificial intelligence.
This study has several limitations and carries implications for future research. First, the generalizability of the results is constrained due to the study being conducted at a single institution. Second, given the growing number of digital health technology studies focusing on older adults, we recommend involving this demographic in the design and development stages to promote a user-centered approach. Third, self-reported data could be better complemented by collecting additional person-generated health data, such as blood pressure and blood glucose levels, sleep cycles, and electrocardiogram readings, through various digital technologies.
The high usability score of HAHA2022 indicates its potential to bridge the digital divide in self-management for older adults by utilizing digital health technologies. Its age-friendly features and digital health coaching capabilities could promote both the successful adoption and ongoing use of the mobile health app among this demographic, thus helping to prevent digital disparities and health inequities.