Time Spent per delta PASI (TSdP) among psoriasis patients undergoing UVB-therapy - A pilot study

Psoriasis often poses a significant challenge to treat. Ultraviolet light band (UVB) treatment is widely used and well recognized. However, the frequent visits to the dermatologist may indirectly present an impediment to many of the patients' careers and every day life due to the vast time burden with subsequent lost work earnings. We investigated the cost-effectiveness of the psoriasis UVB treatment from a patient's point of view using time as a surrogate measure.

Twenty-five patients participated (17 males and 8 females) in the study. We registered the number of UVB treatments per patient as well as the patients PASI (psoriasis area and severity index) score at each treatment session. The time spent in relation to each treatment session was reported in a questionnaire given to the patient. Time Spent per delta PASI (TSdP) was defined as number of minutes to reduce the PASI score by one.

Seventeen (68%) of the participants needed less than 300 min to lower the PASI with one score. The rest (n = 7 (32%)) used more than 300 min to lower the PASI score by one. Thus, the TSdP distribution displayed two peaks; ><300 min/dPASI. Log-transformed linear regression model showed that the expected TSdP would decrease with 42% for each time the start PASI was doubled, i.e. the higher the PASI level at the beginning of the treatment, the lower the TSdP.

The level of reduction in psoriasis severity compared with the amount of lost work time/earnings may pose a much higher impact for patients and society than what is currently recognized.