Background The development and implementation of self-monitoring technologies for chronic conditions would ease the burden on patients and hospital services. Digital applications (apps) on smartphones or tablets can transfer information from a remote setting to a care provider, though technical and practical challenges can arise. The MONARCH study is a multi-centre cohort study evaluating the diagnostic test accuracy of two apps for self-testing visual function at home to detect reactivation of neovascular age-related macular degeneration.

Methods Participants are provided with an iPod to test their visual function weekly using both apps. Data are transmitted automatically using a mobile router to online databases maintained by the app developers. Details of anticipated and unanticipated challenges faced throughout set-up, recruitment and follow-up, and remedial actions, have been carefully documented.

Results As of 17/02/2020, 233/274 (85%) participants (40% male; average age 75) from 6 hospitals self-tested their vision at least once.

Anticipated challenges included potential inequalities in recruitment due to the technologies involved and the need for participant technical support. The primary reason given for non-participation was ‘put off by technology’ (21%). A participant helpline received 186 calls (19.7 hours). Issues with one or both apps was the primary reason for calls (47%), followed by connectivity issues (15%).

Unanticipated challenges included issues setting up and managing iPods remotely, technical issues with the apps, and adherence to self-testing during follow-up. Apple’s multiple device management system was used, which resulted in limited control over devices and failed to prevent standard system updates. System updates interfered with app compatibility and confused some participants. Issues with the app databases temporarily halted recruitment and data monitoring on several occasions and prevented some participants from testing. Participant difficulties in operating the mobile router and issues with app design/interface impeded testing. Phone calls to participants (191, 12.7 hours) were periodically made if data had not been received <14 days since consent or <21 days since previous test. Issues with one or both apps was the primary reason (37%) for lack of data, followed by connectivity issues (26%).

Discussion There are substantial technical and practical issues in providing hardware and implementing digital apps for self-testing visual function with technologically inexperienced patients. Significant support infrastructure is required for patients and device management. Limited control over apps and the requirement for an internet connection added complexities to the testing process in this population. These challenges need to be addressed before implementing digital technologies for self-monitoring that require active patient engagement.