Differences in phototherapy among skin diseases and genders in real-life conditions - a retrospective analysis of the cumulative doses, numbers of sessions, side effects and costs in 561 patients.

Background Phototherapy has been a mainstay therapy for dermatological diseases since more than a century. Although phototherapy is still extensively used and some recommendations exist, only scarce data are available addressing disease-specific differences in cumulative doses, treatment durations and costs. Knowledge of such differences could help to avoid over-/undertreatment, predict treatment duration and costs. Therefore, we sought to determine differences in cumulative doses, numbers of sessions, side effects and costs among different skin diseases and genders in real-life conditions. Methods In this single-center, retrospective study, patients treated with phototherapy between March 2014-April 2019, were classified into 7 diagnostic groups and analysed according to the study goals. Results Out of 561 patients (age 53.9 ±20.3 yrs; 52.9% females), 83.7% percent were treated with cabin NB-UVB (mean cumulative dose 17.79 ±17.11J/cm2 ). Patients with vitiligo and psoriasis were treated with significantly higher cumulative NB-UVB doses (cabin, local) in comparison to the five other diagnostic groups as were males in comparison to females. Consequently, significantly higher UV-related costs resulted in patients with vitiligo, psoriasis and males. Patients with atopic dermatitis and pruritus were treated with significantly higher cumulative UVA1 doses compared to patients with non-atopic eczema. The complication rate (pooled from all UV-modalities) in our population was 3.8% (erythema 3.4%, aggravated itch 0.4% and worsening of symptoms 0.2%). Conclusions Our results demonstrate that cumulative doses and phototherapy-related costs vary strongly amongst skin diseases- a fact not adequately considered in recommendations. A more disease-specific stratification of phototherapy could not only help to optimize outcomes, but also to facilitate comparability of clinical trials using phototherapy.