Development and evaluation of a personalised psychological intervention to improve adherence to photoprotection in adults with Xeroderma Pigmentosum (XP)

Background Poor adherence to photoprotection from ultraviolet radiation in the rare disease xeroderma pigmentosum can be life-threatening due to heightened risk of skin cancers. This novel, two-phase research programme used mixed methods to investigate photoprotection in xeroderma pigmentosum, and its psychosocial impact, to develop an intervention to improve photoprotection. Objective(s) Phase I: To identify barriers to optimal photoprotection. Phase II: To design and test a personalised psychological intervention to improve photoprotection. Design Phase I: Interview study; n-of-1 photoprotection study; objective measurement of ultraviolet radiation exposure study; international cross-sectional survey. Phase II: Consensus conference to synthesise findings and determine targets/priorities for intervention; intervention development using Intervention mapping; randomised controlled trial to test efficacy, cost-effectiveness and intervention mechanisms. Settings for Phases I and II National Xeroderma Pigmentosum Service, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom; Specialist xeroderma pigmentosum clinics in Regensburg, Germany, Japan, Tunisia; Patient support organisations in France and USA. Participants Children < 16 (Phase I only) and adults (> 16) diagnosed with xeroderma pigmentosum. Intervention (Phase II) XPAND is a seven-session personalised psychological intervention designed to be facilitated by non-psychologists, delivered in spring to summer 2018 versus wait list control (intervention in spring to summer 2019). Main trial outcome measure (Phase II) Average daily ultraviolet radiation dose to the face calculated by combining objective ultraviolet radiation exposure with self-reported photoprotection. Results Phase I: Varying levels of photoprotection were found, with most participants doing less than clinically recommended. The international survey (N = 156) and estimation of ultraviolet radiation dose-to-face (N = 41) found that adults had worse photoprotection than the ‘cared for’ sample, but that overall the total dose-to-face was similar in the two groups because the ‘cared for’ group were outside more. The n-of-1 study (N = 20) showed that fluctuations in protection were associated with time of day, weekday versus weekend, environmental risk perceptions and symptoms resulting from exposure, self-regulatory and psychological constructs. The qualitative study (N = 25) identified three modes of adaptation to photoprotection: (1) ‘dominated’, (2)‘integrated’ and (3) ‘resistant’. Modifiable drivers of photoprotection behaviour were identified in the survey studies, including belief-based predictors and the important role of habits. These combined findings informed the development and targets of the XPAND intervention. Phase II: The intervention group (n = 6) had significantly lower daily average ultraviolet radiation dose-to-face (primary outcome) compared to control (n = 7) (−0.25 Standard Erythemal Dose, p 16 years with a confirmed diagnosis of XP, sufficient English language comprehension and no cognitive impairment completed the measures themselves. Parents/caregivers of children (