Efficacy of a far erythemogenic dose of narrow-band ultraviolet B phototherapy in chronic plaque-type psoriasis.

The aim of the present study was to examine the effect of far erythemogenic dose of narrow-band ultraviolet B (NB-UVB; starting dose at 35% minimal erythematous dose [MED]) on clinical response by measuring the severity, extent of disease and the changes in quality of life. Fifty patients with chronic plaque-type psoriasis were enrolled. Therapy was held for 3 days a week. The severity of the disease was assessed based on the Psoriasis Area and Severity Index (PASI) score and Dermatology Life Quality Index (DLQI) scores. The percentage improvement of PASI at 30 sessions was 68.99%. The improvement in DLQI scores at 30 sessions was 79.67%. Pearson correlation coefficients showed that PASI scores were not correlated with DLQI scores at the beginning of treatment (P = 0.330, r = 0.14), but after the 30th session of NB-UVB therapy improvements in quality of life were correlated (P < 0.05, r = 0.399). Therefore, far erythemogenic dose of NB-UVB is considered to be effective treatment for plaque-type psoriasis in our patients. However, we cannot confirm that it is safer than higher MED starting dose in term of cumulative UV irradiation.