Development and usability evaluation of the mobile application for patients with chronic vestibular syndrome Future Health & Technology/ Department of Nursing Science Master's thesis Author: Xuejiao Cao Supervisor(s): Professor Sanna Salanterä Professor Peixia Wu 18.9.2024 Turku The originality of this thesis has been checked in accordance with the University of Turku quality assurance system using the Turnitin Originality Check service. Master's thesis Subject: Nursing Science Author(s): Xuejiao Cao Title: Development and usability evaluation of the mobile application for patients with chronic vestibular syndrome Supervisor(s): Professor Sanna Salanterä; Professor Peixai Wu Number of pages: 105 pages Date: 18.9.2024 Abstract. Background and Objectives Chronic vestibular syndrome (CVS) is nonspecific and often goes untreated, which leads to disability and handicap. And recently, vestibular rehabilitation therapy (VRT) has been recommended as a first-line treatment for CVS. However, its accessibility is limited in China and many other developing countries for several reasons. Therefore, Internet-based approach may be used in situations such as long distance from the hospitals or with financial difficulty. The study had four specific aims: Part1. Determination of the App modules and functions for CVS patients and development of the App prototype. Part 2. Acquisition of user experience. Part 3. Calculation of user requirements importance and determination of optimization strategy Part 4. Usability evaluation of the App Methods In part 1, the researcher conducted two rounds of focus groups:8 specialists in the first group and 11 specialists in the second group, to explore the expected benefits and potential concerns of an App for CVS patients and determine the modules and functions of the App. In part 2, Face-to-face interviews with patients or their main caregivers were conducted in conferences. After the interview, patients were asked to fill out a general information questionnaire. Data collection and analysis were carried out simultaneously in this part. In part 3, based on the KANO model, the survey questionnaire was conducted to further analyze user requirements for App optimization. A combination of electronic and paper-based questionnaires was used. In part 4, usability was evaluated by quantitative research, using user testing and a questionnaire method. Twenty potential users were recruited in this part through the convenience sampling method Results In Part 1 of the study, 8 modules were identified, including 20 specific functions in total. Based on the results of focus groups, an App prototype was developed over six months, encompassing design and coding. In Part 2 of the study (acquisition of user experience), interview results indicated that participants expressed positive evaluations regarding the "perceived usefulness" of this App. However, in terms of usability, there were several impediments, such as the presence of over-specialized content and intricate patterns. Regarding the optimization, 7 user requirements for enhancing user-friendliness were obtained. In part 3 of the study, three optimization suggestions for better usability were finally determined, including more understandable language, adding rehabilitation exercises time- reminder, personalized font size. The post-optimized design and content have garnered recognition from specialists. In Part 4 of the study, from a holistic perspective, the App exhibited favorable usability and garnered a notably high level of user satisfaction. Conclusions This research designed and developed a mHealth App for CVS patients. Based on the KANO model, user experience and optimization requirements for the App prototype were acquired by interviews and importance of these requirements was calculated. Three optimization strategies for better usability were then determined. The usability of this App was evaluated finally and it exhibited favorable usability, garnered a notably high level of user satisfaction. Keywords: Chronic Vestibular Syndrome, Vestibular Rehabilitation, Mobile Health Application; KANO Model; Usability Evaluation Abstrakti Tausta and Tavoitteet Krooninen tasapainohäiriö (CVS) on epämääräinen ja usein hoitamaton tila, mikä johtaa vammaisuuteen ja haittaan. Viime aikoina tasapainoelinten kuntoutushoito (VRT) on suositeltu ensisijaiseksi hoidoksi CVS:lle. Kuitenkin sen saatavuus on rajoitettua Kiinassa ja monissa muissa kehitysmaissa useista syistä. Siksi internet-pohjaista lähestymistapaa voidaan käyttää tilanteissa, kuten pitkien etäisyyksien takia sairaaloihin tai taloudellisen vaikeuden vuoksi. Tämän tutkimuksen tavoitteena oli suunnitella ja kehittää mHealth-sovellus CVS- potilaille ja varmistaa sen käytettävyys. Metodit Tutkimus koostui neljästä osasta: 1) Sovellusmoduulien ja -toimintojen määrittäminen CVS- potilaille ja sovelluksen prototyypin kehittäminen; 2) Käyttäjäkokemuksen hankkiminen; 3) Käyttäjävaatimusten tärkeyden laskeminen ja optimointistrategian määrittäminen; 4) Sovelluksen käytettävyyden arviointi. Tulokset Osa 1: Sovellusmoduulit ja -toiminnot CVS-potilaille ja sovellusprototyypin kehittäminen. Lopulta tunnistettiin 8 moduulia, jotka sisälsivät yhteensä 20 tarkkaa toimintoa. Osa 2: Käyttäjäkokemuksen hankkiminen. Haastattelutulosten perusteella osallistujat ilmaisivat positiivisia arvioita tämän sovelluksen "koetusta hyödyllisyydestä". Kuitenkin käytettävyyden osalta oli useita esteitä, kuten liian erikoistunut sisältö ja monimutkaiset mallit. Optimoinnin osalta saatiin 7 käyttäjän vaatimusta käyttäjäystävällisyyden parantamiseksi. Osa 3: Käyttäjävaatimusten tärkeyden laskeminen ja optimointistrategian määrittäminen. KANO-mallin mukaan suurin vaatimusten tärkeys oli ymmärrettävämmässä kielessä, jonka jälkeen seurasivat harjoitusten aikamuistutukset, asianmukaiset ääniohjeet ja suurempi tekstinäyttö. Edellisten haastatteluiden sisällön ja strategioiden toteuttamiskelpoisuuden perusteella kolme optimointiehdotusta paremmalle käytettävyydelle määritettiin lopulta, mukaan lukien ymmärrettävämpi kieli, harjoitusten aikamuistutuksen lisääminen, henkilökohtainen fonttikoko. Jälkikäteen optimoitu suunnittelu ja sisältö saivat tunnustusta asiantuntijoilta. Osa 4: Sovelluksen käytettävyyden arviointi. Kokonaisvaltaisesti sovellus osoitti suotuisaa käytettävyyttä ja sai huomattavan korkean käyttäjätyytyväisyystason. Johtopäätökset Tämä tutkimus suunnitteli ja kehitti mHealth-sovelluksen CVS-potilaille. KANO-mallin perusteella käyttäjäkokemus ja optimointivaatimukset sovellusprototyypille hankittiin haastatteluilla ja näiden vaatimusten tärkeys laskettiin. Kolme optimointistrategiaa paremmalle käytettävyydelle määritettiin sen jälkeen. Lopuksi tämän sovelluksen käytettävyys arvioitiin, ja se osoitti suotuisaa käytettävyyttä ja sai huomattavan korkean käyttäjätyytyväisyystason. Asiasanat: Krooninen vestibulaarinen oireyhtymä, vestibulaarinen kuntoutus, mobiilisovellus terveydenhuollossa; KANO-malli; käytettävyystutkimus Table of contents Abstract. 3 Abstrakti 4 List of figures and tables 9 Abbreviations 10 1 Introduction 11 1.1 Background 11 1.2 Theoretical significance 12 1.3 Practical significance 12 2 Literature review 13 2.1 Overview of chronic vestibular syndrome 13 2.1.1 Epidemiology and pathogenesis of chronic vestibular syndrome 13 2.1.2 Treatment of chronic vestibular syndrome 13 2.2 review of vestibular rehabilitation 14 2.2.1 The mechanism and contents of vestibular rehabilitation 14 2.2.2 Clinical research status of vestibular rehabilitation 15 2.3 Overview of mHealth application 17 2.3.1 Research status of mHealth application 17 2.3.2 Usability evaluation of mHealth application 18 2.3.3 Research status of mHealth for vestibular rehabilitation 20 2.4 Overview of focus groups 20 2.5 Overview of KANO model 21 2.6 Summary of the literature review 24 2.7 Definition 25 2.7.1 Vestibular rehabilitation therapy 25 2.7.2 Mobile health application 25 2.7.3 Usability 25 3 Research Purpose 26 3.1 Overall aim 26 3.2 Specific goals 26 3.3 Roadmap 27 4 Development of application prototype 28 4.1 Research methods 28 4.1.1 Study design 28 4.1.2 Research participants 28 4.1.3 Research sites and tools 29 4.1.4 Data collection 29 4.1.5 Data analysis 30 4.1.6 Ethical considerations 31 4.1.7 Quality control 31 4.2 Research results 31 4.2.1 Results of focus groups 31 4.2.2 Development of application prototype 39 4.3 Discussion 47 5 Acquisition of user experience 49 5.1 Research methods 49 5.1.1 Study design 49 5.1.2 Research participants 49 5.1.3 Research tools 50 5.1.4 Data collection 50 5.1.5 Data analysis 51 5.1.6 Ethical considerations 52 5.1.7 Quality control 52 5.1.8 Reliability 52 5.2 Research results 53 5.2.1 Demographic data 53 5.2.2 Interviews results 54 5.3 Discussion 62 6 Requirements importance calculation 64 6.1 Research methods 64 6.1.1 Study design 64 6.1.2 Research participants 64 6.1.3 Research tools 64 6.1.4 Data collection 65 6.1.5 Data analysis 65 6.1.6 Ethical considerations 67 6.1.7 Quality control 67 6.2 Research results 67 6.2.1 Demographic data 67 6.2.2 Reliability and validity analysis 68 6.2.3 User requirements classification 69 6.2.4 User requirements importance calculation 70 6.2.5 Define optimization strategies 71 6.3 Discussion 74 7 Usability evaluation 76 7.1 Research methods 76 7.1.1 Study design 76 7.1.2 Research participants 76 7.1.3 Research tools 76 7.1.4 Data collection 76 7.1.5 Data analysis 77 7.1.6 Ethical considerations 77 7.2 Research results 78 7.2.1 Demographic data 78 7.2.2 Effectiveness 79 7.2.3 Efficacy 80 7.2.4 Satisfaction 80 7.3 Discussion 81 8 Conclusion 83 8.1 Conclusion 83 8.2 Innovation points 83 8.3 Limitations and Prospects 84 8.3.1 Limitations 84 8.3.2 Prospects 84 Reference 85 Appendices 99 Appendix 1 Discussion Guide 99 Appendix 2 General Information Questionnaire 100 Appendix 3 Interview Outlines 101 Appendix 4 Informed Consent 102 Appendix 5 KANO questionnaire 103 Appendix 6 System usability scale 104 Acknowledgements 105 9 List of figures and tables Figures Figure 1 Focus group seating plan ........................................................................................................ 21 Figure 2 Kano Model[113] ........................................................................................................................ 23 Figure 1 Roadmap ................................................................................................................................. 27 Figure 2 The home page module .......................................................................................................... 40 Figure 3 Vertigo log module .................................................................................................................. 41 Figure 4 Vestibular function assessment and personalized rehabilitation programs generation .......... 42 Figure 5 Vestibular rehabilitation training module ................................................................................. 43 Figure 6 Dissemination of vertigo knowledge module ........................................................................... 44 Figure 7 Physician consultation module ................................................................................................ 44 Figure 8 Community notes module ....................................................................................................... 45 Figure 9 Make an appointment module ................................................................................................. 46 Figure 10 Personal centre module ....................................................................................................... 46 Figure 11 Medication Guide module. (a) Before optimization; (b) After optimization............................ 72 Figure 12 Rehabilitation exercises time-reminder ................................................................................. 73 Figure 13 Personalized text size adjustment......................................................................................... 74 Figure 14 Task completion and error rate ............................................................................................. 79 Tables Table 1 Kano Questionnaire .................................................................................................................. 22 Table 2 Kano evaluation list .................................................................................................................. 23 Table 3 Expert panels demographic data (N=19) ................................................................................. 32 Table 4 Expected benefits and potential concerns of the App for CVS patients................................... 32 Table 5 Desired functions and modules of the app for patients with CVS ............................................ 36 Table 6 User information form (N=9) ..................................................................................................... 53 Table 7 Interviews results ...................................................................................................................... 54 Table 8 The sample characteristic (N=39) ............................................................................................ 68 Table 9 Reliability and validity of KANO questionnaire ......................................................................... 69 Table 10 Kano classification of user requirements (N=39) ................................................................... 69 Table 11 Self-stated importance of user requirements (N=39) ............................................................. 70 Table 12 Improvement ratio of user requirements (N=39) .................................................................... 70 Table 13 User requirements importance calculation results (N=39) ..................................................... 71 Table 14 The sample characteristic (N=20) .......................................................................................... 78 Table 15 Time on tasks ......................................................................................................................... 80 Table 16 Overview of SUS scores ........................................................................................................ 80 10 Abbreviations CVS Chronic Vestibular Syndrome VRT Vestibular Rehabilitation Therapy UI User Interface J2EE Java 2 Platform Enterprise Edition ISO International Organization for Standardization SUS System Usability Scale BPPV Benign Paroxysmal Positional Vertigo MD Meniere’s Disease 11 1 Introduction 1.1 Background Chronic vestibular syndrome (CVS), commonly defined as having symptoms lasting for 3 months or more, is a nonspecific condition that often goes untreated, resulting in disability and impairment[1]. The prevalence of chronic vestibular symptoms in the adult population is estimated to be between 1.4 and 4.8%[2]. Although the precise causes of CVS are unclear, it is generally accepted that multiple factors are involved[3]. Review of the management of chronic vestibular syndrome indicated that no medication has well-established evidence nor is any medication suitable for long-term use[4]. This underscores the critical role of vestibular rehabilitation therapy (VRT), an exercise-based approach involving movements of the eyes, head, and body to promote vestibular compensation and habituation, first introduced in the 1940s[5]. VRT has recently been recommended as a primary treatment for chronic dizziness[6]. Despite the fact that researches have shown VRT is the most effective therapy for chronic vestibular syndrome, its availability is restricted in China and many other developing nations. There are several reasons for this underutilization. Firstly, the number of therapists with expertise in vestibular rehabilitation is alarmingly low, and many healthcare facilities do not have the required equipment or dedicated spaces to conduct VRT effectively. This shortage and lack of infrastructure impede the widespread adoption of VRT, leaving many patients without access to this crucial therapy. Secondly, from the patients' perspective, body constraints and financial burdens prevent regular clinic visits, especially for older adults, who make up the majority of the patients. For these patients, the costs associated with travel, as well as the logistical difficulties of frequent appointments, can be prohibitive. These barriers are exacerbated in remote or underserved regions where healthcare resources are sparse. In light of these challenges, internet-based approaches to VRT offer a promising solution. Mobile health (mHealth) technology has emerged as a promising tool for fostering patient engagement in healthcare management. Specifically, mHealth tools exhibits substantial potential as a potent mechanism for instigating health behavior modifications, particularly in health prevention and self-management contexts, owing to its omnipresence, portability, and advanced computational capabilities[7]. Consequently, given the great potential of mHealth, it is not surprising that current estimates suggest there are more than 165,000 mHealth applications (Apps)[8] . Although the use of mobile application as a tool to help people with 12 other chronic conditions has been explored and its effectiveness has been proved [7, 9] as well, there remains a conspicuous absence of research concerning mHealth interventions tailored for individuals with CVS. Therefore, addressing this lacuna necessitates the development of dedicated App catering to this specific demographic. To sum up, given the significance of vestibular rehabilitation for patients with chronic vestibular syndrome and the potential of mHealth tools for health education and self- management, this research aims to design and develop a specialized App tailored to individuals grappling with chronic vestibular syndrome. Then the subsequent optimization of this App will be guided by the KANO model, improving user friendliness and satisfaction, followed by a rigorous evaluation through usability testing and questionnaire survey. If this study yields expected effects and is accepted by the patients, it will be an innovative strategy for management of chronic vestibular syndrome. 1.2 Theoretical significance Although mobile health technology is quite mature, there is few research focused on patients with chronic vestibular syndrome. Therefore, this study theoretically provides a new method for research in the field of vestibular rehabilitation by using scientific methods to develop and optimize the application prototype of vestibular rehabilitation and verify its usability. 1.3 Practical significance Cognition of chronic vestibular syndrome and utilization of vestibular rehabilitation is limited in China and many other developing countries until now for some reasons. Developing an App for patients with chronic vestibular syndrome could increase public awareness of the condition and assist patients with vestibular rehabilitation at home rather than frequent hospital visits. What’s more, the beneficiary of this App are not only patients, but also caregivers and therapists. Therefore, it can also help medical workers with patient management, which will improve the efficiency of the hospital. 13 2 Literature review 2.1 Overview of chronic vestibular syndrome 2.1.1 Epidemiology and pathogenesis of chronic vestibular syndrome Chronic vestibular syndrome is a group of clinical syndromes characterized chronic vertigo/dizziness or instability that lasts for months to years, usually with persistent vestibular system dysfunction (visual oscillations, nystagmus gait and instability)[10]. There are also signs and symptoms suggesting dysfunction of the cochlea or central nervous system. CVS is a very challenging problem[11]. Each year around 1 in 20 people in the general population experiences vertigo[12]. Around 80% of these people affected by vertigo find that it severely impairs their daily functioning. Since the symptoms of vertigo prevent many people from working, as well as resulting in an increase in the risk of falling and a high use of healthcare services, vertigo also represents a substantial economic cost. CVS usually presents a progressive, worsening course, and sometimes includes a state of unstable incomplete recovery after acute vestibular disease or a state of persistent symptoms between episodes of episodic vestibular disease[13]. These diseases mainly include bilateral vestibular dysfunction, Persistent postural perceptual dizziness (PPPD), psychogenic dizziness and so on. These peripheral vestibular disorders induce an important innate repair mechanism known as vestibular compensation, which aids functional recovery after damage to the vestibular system[14]. However, there is a large inter-individual variation in the rate and level of recovery. Chronic vertigo occurs when natural vestibular compensation fails[10]. 2.1.2 Treatment of chronic vestibular syndrome Vestibular rehabilitation is now considered the preferred treatment for patients with chronic vertigo and is recommended by USA[15] clinical practice guidelines. In spite of this guidance, anti-vertigo drugs such as Betahistine are commonly prescribed, and vestibular rehabilitation is hardly used to treat chronic vertigo. An observational study of patients with vertigo from 13 different European countries (4294 participants) found that Betahistine was prescribed to more than two thirds of patients with vertigo in general practice at the first consultation and was still being used six months later[16]. In contrast, surveys of general practitioners in the Netherlands (n=426)[17] and UK (n=53)[18] found that only 5.8-6.8% used vestibular rehabilitation. 14 2.2 review of vestibular rehabilitation 2.2.1 The mechanism and contents of vestibular rehabilitation The powerful compensatory potential of vestibular system and the great plasticity of balance system are the foundation of vestibular rehabilitation[19]. Vestibular adaptation, vestibular acclimation and sensory substitution are known to be the main mechanisms of vestibular rehabilitation[20]. The unique value of vestibular rehabilitation is to improve the ability to see clearly during movement, reduce vertigo symptoms, reduce instability/imbalance, help patients return to normal life, and reduce social alienation[21]. Vestibular adaptation needs to be modified by vestibular ‑ ocular reflex exercises. Gaze stability training is a classic movement of vestibular rehabilitation, which requires two sensory stimuli-visual and head movements[22]. Vestibular adaptation is induced by error signals caused by retinal slide to increase the gain of vestibular response[21], the most effective is that the eye is fixed to the visual target when the head moves in the horizontal and vertical plane, and the exercise on the roll plane has little change in vestibular ‑ ocular reflex gain[19]. Vestibular acclimation is a central learning process that is primarily used for symptoms of visual/motor sensitivity[23]. Repeated exposure to symptom-induced situations, including specific motor or visual environments, can gradually reduce response intensity, which is the basis of acclimation training, the specific mechanisms and neural circuits are not yet understood. Once established, the habit can be maintained for a period of time, and repeated training can be maintained for a longer time. However, bilateral vestibular dysfunction is not an indication of conditioned exercise, since vestibular conditioning is designed to reduce unwanted responses to vestibular signals and does not improve gaze or postural stability[24]. It is also important to note that older adults should avoid certain conditioned movements (such as rising quickly) that may cause postural hypotension. Early acclimatization training can aggravate symptoms and lead to reduced compliance, which should be fully explained in clinical application[25]. Sensory substitution is an alternative mechanism to replace the impaired vestibular function through vision, proprioception, neck-eye reflex, etc.[26]. Because of the frequency characteristics, the application environment of sensory substitution is limited. For example, in poor lighting environment and uneven ground, visual and proprioceptive substitution effect is obviously insufficient. The neck-eye reflex also works only at very low frequencies (<0.5 Hz) 15 and does not contribute much to visual stability during head movements[27]. For unilateral vestibular dysfunction, controlled balance can be achieved through vestibular compensation, and sensory substitution is of little significance. For patients with bilateral vestibular function loss, sensory substitution obviously plays an important role, but the specific mechanism is still little known, and overuse of vision is thought to play a major role[28]. In most cases, postural stability exercises are an integral part of vestibular rehabilitation, and the core idea is to adequately challenge more difficult balance tasks without falling[29]. The training methods can be summarized as: standing, walking and turning under the condition of removing or changing visual cues and interfering with proprioception (such as foam pad or moving platform)[30], and repeated reinforcement based on the theory of motor learning to improve the comprehensive use of visual and somatosensory information, and enhance the formation of vestibular signals and central preprogramming. Gait speed < 0.8m /s indicates the need for gait training[21]. During gait exercises, head movements (such as nodding and shaking) can be combined at the same time to correct the "protective strategy" of vestibular dysfunction patients who are accustomed to not turning their heads during movement, and excessive fixation can also be corrected[31]. Regarding the timing and frequency of vestibular rehabilitation, the guidelines[32] recommend that patients with acute/subacute vestibular dysfunction perform gaze stabilization exercises at least 3 times per day, with a total exercise time of no less than 12 minutes per day, and patients with chronic vestibular dysfunction at least 20 minutes per day. For patients with acute and subacute vestibular dysfunction, there is no specific dose of balance exercise recommended for the time being[33]. Patients with chronic vestibular dysfunction should perform balance exercise for at least 20 minutes a day for at least 4-6 weeks[32]. The patient's symptoms disappear, or the condition is stable and the curative effect has reached a plateau, which can be used as an indication to stop vestibular rehabilitation training. However, if the patient's compliance is poor, the clinical condition continues to deteriorate or the vestibular function state fluctuates (such as Meniere's disease activity phase), and there are psychosomatic problems, which hinder the vestibular rehabilitation effect, the rehabilitation practice can be stopped[34]. 2.2.2 Clinical research status of vestibular rehabilitation The efficacy of vestibular rehabilitation is not affected by the patient's age, gender, etc[35]. Whether it is peripheral, central or mixed lesions, as long as the patients with stable non- 16 progressive lesions and spontaneous mal-compensation, vestibular rehabilitation can be used as the primary treatment[36]. The effect of vestibular rehabilitation on unilateral/bilateral vestibular dysfunction is the most common research direction[37], and the main research results are fully summarized in the "Practice Guide for Vestibular Rehabilitation in Patients with External vestibular Dysfunction" published in 2016[15]. Strong evidence (3 randomized controlled trials) shows that: Vestibular rehabilitation can bring clear and substantial benefits for patients with acute or subacute unilateral vestibular dysfunction, and the earlier the start, the better; (2) Patients with chronic unilateral/bilateral vestibular dysfunction can also benefit from vestibular rehabilitation; (3) Saccades and smooth tracking exercises alone are not effective and may also waste time and delay effective treatment[15]. After 2016, a number of high-quality randomized controlled studies have been carried out in succession. Additional evidences include: (1) vestibular neuritis is equally effective in vestibular rehabilitation as hormone therapy. Hormone seems to accelerate the remission of acute symptoms, but has no additional benefits for long-term prognosis[38, 39]; Are vestibular rehabilitation and hormonal therapy more beneficial? One study concluded that combination therapy has no greater benefit than monotherapy[39], and another concluded the opposite[40], but these differences do not seem to shake the importance of vestibular rehabilitation in the treatment of vestibular neuritis. (2) Vestibular rehabilitation can significantly reduce the number of falls in the elderly[41]. The experimental group received dynamic balance and visual motor training, while the control group received no rehabilitation intervention and only encouraged walking to improve general physical condition. At 12-month follow-up, the number of falls in the experimental group decreased from 10.96 in the first year before rehabilitation to 3.03, while the number of falls in the control group had no significant change. (3) For vestibular rehabilitation of the elderly with balance disorders (using dynamic balance table), the effect of 5 courses is equivalent to 10 courses, and this study has answered the question of rehabilitation duration for the first time[42]. However, the popularization and promotion of vestibular rehabilitation is a universal challenge worldwide. Foreign surveys have found that less than 3% of patients have access to vestibular rehabilitation services[43]. The research and practice of vestibular rehabilitation in China started not late. Since 2003, a number of professional articles have been published[44, 45], and colleagues in the industry have been fully prepared in terms of knowledge system. But its accessibility is limited in China and many other developing countries for some reasons. 17 Therefore, how to establish an intelligent, remote and home-based practice model to improve the accessibility of vestibular rehabilitation services is one of the new research hotspots. 2.3 Overview of mHealth application 2.3.1 Research status of mHealth application Nowadays, mobile phones are so prevalent that they are now an integral part of daily life[46]. With the widespread availability of these devices and the convenience they offer, mobile health (mHealth) has gained unprecedented traction[47]. mHealth refers to the use of mobile technologies to enhance and support public health initiatives[48, 49]. This approach has evolved into a vast tool that empowers patients to take charge of their own care, fostering greater patient-centred care and contributing to an improved understanding of health conditions, ultimately shifting public perceptions in a positive direction[50]. Currently, over 325,000 health apps can be found on app stores across various mobile platforms[51]. Researchers have systematically evaluated highly-ranked apps designed for users across all age groups[52-56]. In various studies, the analysed apps offered minimal features, primarily emphasizing information dissemination or educational purposes, along with tools for tracking and self-monitoring activities (such as counting calories or steps, using calendars and so on)[57]. Despite advances in technology, all-encompassing, multifunctional mobile applications are still uncommon[58]. Many free apps, in particular, lack features like exercise routines, dietary plans, individualized feedback, or access to certified professionals[56, 59]. The advent of advanced smartphone technologies has significantly enhanced the potential of mobile health solutions. A health App today can track various personal metrics such as heart rate, mood, activity levels, sleep habits, diet, hydration, and even sexual behaviour throughout the day. As a result, the real potential of mobile health apps is in their ability to customize and adjust interventions for behaviour change in real time, leveraging user and environmental data to enhance health[60]. While mobile applications have been examined for their effectiveness in managing various chronic conditions, there has yet to be a study focused specifically on individuals with chronic 18 vestibular syndrome. The absence of such research highlights a significant gap in the current literature. To sum up, if this study demonstrates that mobile applications can effectively enhance balance function and emotional well-being for those with chronic vestibular syndrome, it could introduce a pioneering approach to managing this condition. Such findings would not only contribute to the existing body of knowledge but also potentially offer a novel and practical solution for improving quality of life in this patient population. 2.3.2 Usability evaluation of mHealth application With the promulgation of relevant policies, mobile medical Apps also show a blowout growth. How to improve the availability level of mobile medical Apps and improve users' satisfaction with mobile medical has become an important issue facing the development of mobile medical[61]. Until now, 16 evaluation tools related to mobile health usability were identified. 13 mHealth usability assessment tools from abroad, they are the mobile Health availability assessment scale (MAUQ)[62], MARS[63], uMARS[64], Health-ITUES[65], TUQ[66] SUTAQ[67], TSUQ[68], TSQ[65], TMPQ[69] and 3 unnamed scales. Five other assessment tools are from China, mainly developed in the form of evaluation index system. Among all these 16 tools, 14 evaluation tools have been verified by the developers, and the verification methods are mainly questionnaire survey and experimental method. Of the 16 tools, 4 were developed based on telemedicine systems. In addition, the Italian National Institute of Health proposed the telemedicine quality control process TM-QC[70]. The assessment object of Health-ITUES is adult AIDS patients, and the format of the scale is open, which will undoubtedly bring some difficulties to researchers who have no experience in using questionnaires[14]. SUTAQ, TSUQ, and TSQ were developed to understand patient satisfaction, which is just one of many metrics used to assess availability[71]. Usability assessment questionnaires developed from a healthcare perspective include TUQ and uMARS[72]. MARS was developed and designed for researchers, and uMARS is based on MARS. Although MARS and uMARS have been widely used by researchers to evaluate the quality of a certain type of health APP in recent years, MARS and uMARS focus on evaluating the quality of mobile medical Apps, which reduces the measurement of application effectiveness and user experience to some extent[73]. 19 In addition, due to the different attributes of the evaluated products, researchers often use different evaluation indicators. Demiris[69] found that privacy, data confidentiality, use and reliability of telemedicine are important factors affecting patients' acceptance of telemedicine care. Leming Zhou[62] et al. developed and verified the mobile health usability questionnaire MQUA, which included three indicators: ease of use, interface and satisfaction, and usefulness. Stoyan[63] extracted 372 clear criteria for evaluating Web or application quality through literature analysis, and summarized them into four objective quality scales (engagement, functionality, aesthetics, and information quality) and one subjective quality scale. The telemedicine usability evaluation scale TUQ summarizes the important roles of usefulness, ease-of-use and learnability, interface quality, interaction quality, reliability, satisfaction and future use on its usability[66]. Chen Yue [74] found that the utility of APP, professional ability of perceived consultation, e-health literacy and perceived health threat had a positive impact on users' willingness to continue using online consultation APP. Hou Xiong[75] et al. explored the service demand of Internet hospitals based on the KANO model and found that assurance, type, reliability, reactivity and caring affect users' evaluation of service quality of Internet hospitals. It can be seen that there is no clear classification standard for existing usability indicators, and the selection and naming of usability indicators are also different. Therefore, many researchers recommend a more widespread use of International Organization for Standardization (ISO) guidelines and techniques[76] to guide usability evaluations[77], which could help expanding usability testing to be more systematic and complete can help build a science of mHealth usability. More standardized, comprehensive approaches would improve methodological consistency, making it possible to begin comparing findings across mHealth application evaluations[78]. Researchers need to assess the full set of recommended measures4effectiveness, efficiency, and satisfaction4to obtain a more thorough picture of the usability of any application[78, 79]. Specifically, effectiveness refers to what extent the user can achieve a goal with accuracy and completeness, while efficiency means the level of effort and resource usage which is required by the user in order to achieve a goal in relation to accuracy and completeness. And satisfaction means the positive associations and absence of discontent that the user experiences during the performance. In that vein, my research employs ISO 9241-11 and techniques to evaluate the usability of the Health app . 20 2.3.3 Research status of mHealth for vestibular rehabilitation The low clinical popularizing rate of vestibular rehabilitation is a common problem worldwide[21]. Mobile health Apps can alleviate this problem to some extent[80]. A Singapore study[81] has preliminarily demonstrated the feasibility and usability of the mobile VRT in healthy older adults. But this study has some limitations, for example, only English-speaking old adults were recruited. There are also studies that verify vestibular rehabilitation based on WeChat platform[82]. The results showed that the patients' homeostasis function and vestibular activity were improved. Vugt VV et.al[83] developed O>A>I[139]. User satisfaction was calculated using a better-worse coefficient with the formulas: SII = (A+O) / (A+O+M+I) DDI = − (O+M) / (A+O+M+I) The user satisfaction index Ti is calculated by integrating the two[140]: Ti = max (|SII| |DDI|) The absolute value of SII and DDI is between 0 and 1. The importance level of user needs is lower when the value tends toward 0 and is higher when it tends toward 1. Based on the Kano model, a single qualitative analysis is not enough to capture user requirements, so the adjustment coefficient k is introduced, taking the values 1.5, 1, 0.5 and 0 to indicate the attractive requirements, one-dimension requirements, must-be requirements, and indifferent requirements, respectively[141]. The target satisfaction and current satisfaction were described in terms of averages. And the improvement rate Vi of user requirements satisfaction is the quotient between target satisfaction S1 and current satisfaction S0[138]: Vi = S1 / S0 67 The greater the value of the improvement rate, the greater the gap between the current state of the requirement and the user's ideal state of the requirement, and the more it needs to be optimized. The importance of user requirements was calculated based on the classification of user requirements by Kano model and combining various factors, including user satisfaction index, Kano classification requirements, improvement rate of user satisfaction and self-stated importance score. Combining these factors, the final goal was to obtain a scientific and reasonable comprehensive score of user requirements importance Zi[138]: Zi = (1 + Ti) k × Vi × Hi Then, the user optimization requirements were sorted in order of importance. 6.1.6 Ethical considerations The study has got approval from the Ethics Committee of Fudan ENT Hospital (reference No. 2019091). The respondent voluntarily participated in the project research, and signed an informed consent form. This study may involve collecting sensitive health information, so the research should ensure that data is encrypted and only accessible to authorized personnel. 6.1.7 Quality control 1) The data collection process strictly followed the standardized questionnaire issuing procedures and used the same filling guidelines. When the questionnaire was collected, the quality of the questionnaire was checked on the spot. If there were any missing items or invalid questionnaires, the subjects were asked to supplement. 2) The questionnaire data were typed in SPSS 26.0 by two people, and SPSS 26.0 was used for preliminary analysis of the data to check whether there were any omissions and logical errors, so as to ensure the authenticity and accuracy of the data. 6.2 Research results 6.2.1 Demographic data A total of 45 questionnaires were distributed, and respondents spent no less than 300 s answering them, of which 39 results were valid, representing a return rate of 87%. 6 68 questionnaires were excluded due to incomplete data. The general information of respondents is shown in Table 8. Table 8 The sample characteristic (N=39) Project Samples (N=39) Gender Male 19(48.72%) Female 20(51.28%) Age 48.64 ± 10.35 Educational Lever Junior high school and below 13(33.33%) Senior high or vocational school 15(38.46%) Undergraduate 9(23.08%) Master or above 2(5.13%%) Employment Status Student 4(10.26%) Employed 17(43.58%) Unemployed 4(10.26%) Retired 13(33.33%) Others 1(2.57%) Years of Diagnose Less than one year 14(35.90%) One to three years 19(48.71%) Three years or more 6(15.39%) Accompanying Symptoms Tinnitus 17(43.58%) Headache 15(38.46%) Hearing loss 18(46.15%) Blurred vision 15(38.46%) Others 6(15.39%) Underwent Vestibular Rehabilitation Before Yes 21(53.84%) No 18(46.16%) 6.2.2 Reliability and validity analysis Before the classification and calculation, Cronbach α coefficients were used to conduct reliability analysis, KMO values and Bartlett's sphericity test were used to conduct validity analysis of the valid KANO questionnaires. 69 Table 9 showed that the Cronbach α coefficients of the positive questions and the reverse questions were 0.918 and 0.879, respectively, demonstrating good internal consistency and reliable survey results. KMO values were 0.628 and 0.832, respectively, the cumulative variance contribution rates were 71.694% and 79.941%, and passed the Bartlett's sphericity test (p＜0.05), showing that the questionnaire had good structural validity and the research item information could be effectively extracted. Table 9 Reliability and validity of KANO questionnaire KANO Questionnaire Sample Size Cronbach α coefficients KMO values Bartlett's sphericity test Approx. Chi-Squire df p Positive Questions 39 0.918 0.628 352.359 66 .000 Reverse Questions 39 0.879 0.832 516.361 66 .000 6.2.3 User requirements classification Requirements analysis was based on KANO model, and the maximum frequency method was employed to determine the attributes of each user requirement. If there were multiple identical Kano category percentages for the same user needs, the classification was determined according to the influence of the Kano categories, that is, M>O>A>I. In this study, U1, U4, U5 represents attractive requirements, U2 represents one-dimensional requirements, U7 represents as indifferent requirements, and U3, U6 represents must-be requirements. The details of each item are shown in Table 10. Table 10 Kano classification of user requirements (N=39) User Requirements Kano Attribute Category Final Category A M O I R U1 19 5 3 10 2 A U2 12 8 15 4 0 O U3 7 18 3 11 0 M U4 16 9 4 8 2 A U5 15 12 5 7 0 A U6 5 19 8 5 2 M U7 13 5 1 20 0 I Notes: Attractive requirements (A), One-dimensional requirements (O), Must-be requirements (M), Indifferent requirements (I), Reverse requirements (R). 70 6.2.4 User requirements importance calculation 4.2.4.1Self-stated importance The self-stated importance Hi within effective questionnaires underwent systematic analysis and categorization. The mean scores, rounded to the nearest whole number, were computed for each requirement, serving as a quantitative representation of the self-stated importance attributed to user needs. The precise outcomes of this analytical process are delineated in Table 11. Table 11 Self-stated importance of user requirements (N=39) Serial Number User Requirements Self-stated Importance (Hi) U1 Larger text display 3 U2 Understandable language 5 U3 User-friendly patterns 2 U4 Appropriate voice prompts 4 U5 Rehabilitation exercises time-reminder 4 U6 Appointment register and follow-up visit instruction 4 U7 More attention to psychological condition 4 4.2.4.2 Improvement ratio The target satisfaction S1 and current satisfaction S0 are shown in Table 12. And the improvement ratio Vi was calculated to ascertain which aspects exhibit significant potential for optimization. Table 12 Improvement ratio of user requirements (N=39) User Requirements Current Satisfaction (S0) Target Satisfaction (S1) Improvement Ratio (Vi) U1 4 4 1 U2 3 5 1.67 U3 2 4 2 U4 3 4 1.33 U5 2 4 1.67 U6 3 4 1.33 U7 3 4 1.33 4.2.4.3 User requirements importance 71 User satisfaction Ti was calculated using a better-worse coefficient, which is shown in Table 12. Based on the Kano model, a single qualitative analysis was not enough to capture user requirements, so the adjustment coefficient k is introduced, taking the values 1.5, 1, 0.5 and 0 to indicate the attractive requirements, one-dimension requirements, must-be requirements, and indifferent requirements, respectively. Combining all factors mentioned above, the comprehensive score of user requirements importance Zi were calculated based on the formula referenced in Chapter 4, Section 1.5, which is shown in Table 13. Table 13 User requirements importance calculation results (N=39) Notes: Attractive requirements (A), One-dimensional requirements (O), Must-be requirements (M), Indifferent requirements (I), Reverse requirements (R), User satisfaction (Ti), Self-stated importance (Hi), Improvement ratio (Vi), the adjustment coefficient (k), User requirements importance (Zi). 6.2.5 Define optimization strategies According to the final results of KANO questionnaire, user requirements items were sorted in order of importance (Table13). Researcher then collaborated with UI designers and software developers to formulate specific optimization strategies to realize these high importance requirements. Based on the previous interview results and the feasibility of strategies, the following three optimization suggestions for better usability are finally determined, including more understandable language, adding rehabilitation exercises time-reminder and personalized font size. The optimization process was conducted during Dec 2023 to Jan 2024. The post-optimized design and content have garnered recognition from specialists. Specifically, as follows. 4.2.5.1 More understandable language User Requirements KANO Category SII DDI Ti Hi Vi k Zi U1 A 0.59 -0.22 0.59 3 1 1.5 6.01 U2 O 0.73 -0.59 0.73 5 1.67 1 14.45 U3 M 0.26 -0.54 0.54 2 2 0.5 4.96 U4 A 0.55 -0.30 0.55 4 1.33 1.5 10.26 U5 A 0.51 -0.46 0.51 4 1.67 1.5 12.39 U6 M 0.35 -0.73 0.73 4 1.33 0.5 5.32 U7 I 0.36 0.15 0.36 4 1.33 0 0 72 Based on the interview results, it was unanimously believed that the poor readability of App prototype was primarily manifested in the Medication Guide module, which was shown in Figure 13a. Therefore, without deviating from the original intended meaning, researcher rephrased the medication guidelines using a more accessible language style. Furthermore, with the goal of improving readability and aesthetic appeal, designers restructured the layout and incorporated specific colors as well as graphic pattern to ensure users can efficiently find the information they seek, which was shown in Figure 13b. Figure 11 Medication Guide module. (a) Before optimization; (b) After optimization. 4.2.5.2 Adding rehabilitation exercises time-reminder The potential-users engaged in qualitative and quantitative research collectively acknowledge the paramount importance of enhancing compliance in vestibular rehabilitation. They asserted the necessity for appropriate reminders, as individuals commonly tended to forget taking rehabilitation exercises, particularly when symptoms exhibited improvement. 73 Therefore, in an effort to prompt users to engage in rehabilitation without causing undue inconvenience, a "daily scheduled reminder" mechanism was implemented within the APP- VRT. Drawing upon practices from other mHealth Apps, like Apple Health, etc., notifications were systematically dispatched to users’ mobile phone at designated times to remind them to undertake their daily rehabilitative training regimen in App, which was shown in Figure 14. Figure 12 Rehabilitation exercises time-reminder 4.2.5.3 Personalized font size Some participants contended that the font in the App prototype was undersized, potentially impacting their usability. However, there was also a contingent of users who argued that the font should not be excessively large, as it may compromise the aesthetic appeal of the App and inadvertently convey the impression that the App was exclusively designed for the elderly, thereby diminishing younger user engagement. Therefore, taking into account various opinions, researcher and designers added the "text size adjustment" function in the App. This allowed users to customize the font size within the App according to their individual preferences, as illustrated in Figure 15. 74 Figure 13 Personalized text size adjustment 6.3 Discussion This section prioritized user requirements in accordance with the KANO model, and then synthesized qualitative and quantitative research results to determine the optimization strategy for the App prototype. The quantitative results showed that the