A personalised and systematically designed adherence intervention improves photoprotection in adults with Xeroderma Pigmentosum (XP): Results of the XPAND randomised controlled trial.

Background: Poor adherence to photoprotection in Xeroderma Pigmentosum (XP) increases morbidity and shortens lifespan due to skin cancers.
Objective: To test a highly personalised intervention (XPAND) to reduce the dose of ultraviolet radiation (UVR) reaching the face in adults with XP, designed using known psychosocial determinants of poor photoprotection.
Methods: A two-arm parallel group randomised controlled trial, including patients with sub-optimal photoprotection to receive XPAND or a delayed intervention control arm that received XPAND the following year. XPAND comprises seven one-to-one sessions targeting photoprotection barriers (e.g., misconceptions about UVR) supported by personalised text messages, activity sheets, and educational materials incorporating behaviour change techniques. The primary outcome, mean daily UVR dose-to-face across 21 days in June-July 2018, was calculated by combining UVR exposure at the wrist with a face photoprotection activity diary. Secondary outcomes were UVR dose-to-face across 21 days in August 2018, time spent outside, photoprotective measures used outside, mood, automaticity, confidence-to-photoprotect. Financial costs and quality-adjusted life years (QALYs) were calculated.
Results: 16 patients were randomised, 13 provided sufficient data for primary outcome analysis. The XPAND group (n=8) had lower mean daily UVR dose-to-face [0.03 SED (SD 0.02] compared to control (n=7) [0.36 SED (SD 0.16)] (adjusted difference=-0.25, p<0.001, Hedge's g=2.2). No significant between-group differences were observed in time spent outside, photoprotection outside, mood, or confidence. The delayed intervention control showed improvements in UVR dose-to-face (adjusted difference=-0.05, Hedge's g=-0.1) , time outside (adjusted difference=-69.9, Hedge's g=-0.28), and photoprotection (adjusted difference=-0.23, Hedge's g=0.45), after receiving XPAND. XPAND was associated with lower treatment costs (£-2642; 95% CI: -£8715 to £3873) and fewer QALYs (-0.0141; 95% CI: -0.0369 to 0.0028).
Conclusions: XPAND was associated with a lower UVR dose-to-face in XP patients and was cost-effective.
(© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists.)