P202 Indoor vs. outdoor daylight photodynamic therapy for multiple actinic keratoses: a weatherproof approach

Abstract

Daylight photodynamic therapy (PDT) is a minimally invasive treatment for multiple actinic keratoses (AKs). Its efficacy is comparable with that of conventional PDT, but it has significantly less pain and better tolerability. In the UK, daylight PDT is limited between November and March due to insufficient light intensity and can be affected by adverse weather throughout the year. This study investigated whether indoor PDT using an artificial daylight lamp is effective, allowing treatment to be delivered year-round regardless of weather conditions. In total, 54 patients with multiple AKs received either indoor or outdoor daylight PDT, determined by weather conditions on the day of review. A minimum of 34 patients were required to evaluate an equivalence margin of 20%. Skin preparation included application of ­ultraviolet-protective sunscreen, cleansing and curettage, followed by application of 5-aminolevulinic acid to affected areas. Indoor PDT involved a 1-h incubation and 1 h of artificial light exposure, while outdoor PDT used a 30-min incubation followed by 2 h of natural daylight. Efficacy was assessed using Actinic Keratoses Area and Severity Index (AKASI) scores before and after treatment. In total, 24 patients received indoor PDT (all male; mean age 79 years) and 30 received outdoor PDT (29 male, 1 female; mean age 80 years). The scalp was the most treated site, a clinically challenging area with the highest skin cancer risk. Mean baseline AKASI scores were 4.4 and 4.8 in the indoor and outdoor groups, respectively, with no statistically significant difference between the groups (P = 0.29). There was a 23% (95% confidence interval 10.9–35.1) mean improvement in AKASI scores following treatment in the indoor group, compared with 28.9% (95% confidence interval 15.6–42.2) in the outdoor group, with no significant difference between the two groups (P = 0.54). In our study, indoor artificial daylight PDT demonstrated equivalent efficacy to standard outdoor daylight PDT, which supports indoor artificial daylight PDT as an effective year-round treatment option.