User-Centred Design of a Patient App for Carotid Artery Monitoring at Home

The World Health Organization (WHO) reports that cerebrovascular diseases account for the second highest cause of death in Europe, contributing to 11% of annual deaths. One of the underlying causes is a stenosis, which refers to the blockage or narrowing of the carotid artery due to the accumulation of plaque within the artery. Although stenoses can result in severe health complications such as strokes, early detection can prevent such complications. The BODYTUNE system aims to detect building stenoses in high-risk patients through an AI-supported auscultation device. This device is accompanied by an app that enables users to take independent measurements from home and manages and displays the results. The development of a high-fidelity interactive prototype of this app is the subject of this paper. The app prototype was developed using the Human-centred design process, an approach defined by the International Organization for Standardization (ISO) that places emphasis on the needs and preferences of the user, ensuring that the resulting product meets a high level of usability. To ensure user centricity towards the system's target group a survey of potential at-risk patients for a carotid stenosis was conducted, investigating their needs and abilities, and obtaining design requirements. Inquired points included participants' experience with handling medical systems in home use and their general affinity for technology. The survey revealed that most participants have prior experience with comparable systems such as blood pressure monitors or health and lifestyle apps. However, participants were still concerned about being able to operate the system independently and feared making errors in the measurement process, leading to false results. The survey highlighted the importance of designing an app that is easy to use, instils trust between the system and the users, validates users in their actions, and guides them when problems arise. After the initial research a design was established through several iterations, starting from wireframing to the final design of the interactive prototype. It aims to be trustworthy and professional and convey a positive feel and calming feel. The prototype covers the four following use cases: establishing a connection between the measuring device and the app, taking a measurement, looking up former measuring results and editing profile information. Subsequently to the prototype development a usability test was conducted to assess whether the design met the requirements for the target group and to identify potential usability problems. Six people, representing potential users of the app, participated in the test, and were asked to independently execute each use cases. The tests were observed, and the prototype device was screen recorded. Additionally, an interview was conducted afterwards where participants were asked about their specific struggles and general aspects regarding the app's usability. In total, 24 usability problems were identified from the test, almost two-thirds of which were pointed out by more than one test participant. Despite these issues, participants generally displayed a positive reaction towards the app, stating they feel safe and reassured during use and feeling that the BODYTUNE system would be helpful to them.