Predictors of Adherence to Narrowband Ultraviolet B First-month Treatment Dosage Plan

Background: The adherence to a narrowband ultraviolet B (NB-UVB) treatment plan is derived, in large part, from the patient's skin tolerance to the phototherapy dose. At present, the initial and first-month incremental phototherapy doses are determined prior to treatment initiation based on the patient's Fitzpatrick skin phototyping. Objectives: To identify variables that predict adherence to NB-UVB first-month treatment dosage plan. Methods: Charts of 1000 consecutive patients receiving NB-UVB at a hospital-based phototherapy unit were retrospectively analyzed. We included patients receiving NB-UVB for atopic dermatitis, psoriasis, vitiligo, and mycosis fungoides. The first-month NB-UVB treatment plan was determined based on the patient's Fitzpatrick phototype. Adherence to treatment was defined as receiving at least 80% of the planned first-month cumulative dose. We compared adherent vs. non-adherent patient groups for age, sex, Fitzpatrick phototype, presence of freckles, nevus count category, and type of dermatological disease. Results: The study included 817 eligible patients, mean age 40 (2-95) years; 54% men; 32% had Fitzpatrick phototype l-ll. Distribution by diagnosis was atopic dermatitis (29%), psoriasis (27%), vitiligo (23%), and mycosis fungoides (21%). Adherence to NB-UVB treatment plan was observed in 71% of patients. Adherence decreased with age, with 7% decrease per year (P = 0.03) and was higher among mycosis fungoides patients (77.3%) compared to all other diagnoses (69.8%; P = 0.02). Conclusions: Adherence to NB-UVB treatment may be related to age and diagnosis. Fitzpatrick phototype-based first-month treatment plans should be modified accordingly.