Efficacy of an appearance-based and a health-based sun protection intervention on summer vacationers' behaviours, PRISME cluster randomized crossover trial, France.

Objectives: Sun-seeking vacationers are particularly vulnerable to melanoma. Appearance-based interventions (ABi) showing skin damage of ultraviolet exposure may be a promising prevention tool to improve skin protection. This study aimed to measure and compare the efficacy of an ABi and a health-based intervention (HBi) on French summer vacationers' behaviours and to identify differences between subpopulations.

Design: A cluster randomized crossover trial with three intervention groups (control, ABi, HBi) was conducted in eight campsites on the French Mediterranean coast in summer 2019.

Methods: 1355 vacationers of both sexes and aged 12-55 years were included and followed up after 4 days (T1) and 14 months (T2). Efficacy of interventions was evaluated using multilevel mixed-effect models comparing groups on three outcomes: self-reported sun protection behaviours, sunbathing and skin colour measures. Protection behaviours were analysed according to subpopulations.

Results: Compared to controls, the ABi group had a higher protection and sunbathed for fewer hours at T1 and T2. In the HBi group, the skin colour was lighter than controls at T1. When comparing ABi to HBi, ABi participants had lower exposure than HBi at T1 and T2. The protection of people with a 3-years university degree was higher in the HBi group than in others groups while that of people with a secondary school certificate was higher in the ABi group.

Conclusions: Our study provides further evidence of individual sun protection interventions effect in a touristic setting and highlights the relevance of ABi messages to supplement HBi messages, particularly in certain subpopulations with low to intermediate education levels.