PD13 Evaluating a smartphone-based solar exposure tool for supporting management of photodermatoses

Abstract

Photodermatoses such as solar urticaria and chronic actinic dermatitis cause heightened sensitivity to outdoor and, in some cases, indoor light, leading to pain, pruritus and prolonged erythema. These conditions substantially affect quality of life, with rates of psychological comorbidity higher than in the overall population. Management relies on rigorous photoprotection and limiting exposure to ultraviolet and visible light, yet many patients struggle to judge real-time light conditions and remain uncertain when cumulative exposure may reach their individual symptom threshold. Few tools provide personalized, objective feedback to help guide everyday decisions about light avoidance. Following discussions with patients, we explored the potential of repurposing ExpoDose®, a research-grade solar monitoring platform, as a support tool for managing photosensitivity. ExpoDose® integrates GPS-derived location and satellite irradiance data to estimate ambient solar exposure through a smartphone app. The APPETISER study (Assisting Photosensitive Patients Excel Through Information on Sun Exposure: a Realism Study) was developed as a clinical service initiative to evaluate technical feasibility, usability and perceived value for individuals living with photosensitivity. Engagement was high, with 89% of participants using the app daily and reporting it to be easy to use. Overall, 78% expressed at least some level of satisfaction, and 67% felt their ability to manage photosensitivity improved during the evaluation. When asked to rate the app’s contribution to this improvement on a 0–10 scale, the mean score was 7. Although 89% wished to continue using the app, only 11% were willing to pay for it in its current form. A 35% dropout rate, largely due to technical issues, influenced overall outcomes. Nonetheless, patient responses demonstrated strong interest in tools that help contextualize daily solar exposure and support self-management. Although the app will not enter routine practice, future work will explore what motivates behaviour change among people living with photodermatoses.