Conventional phototherapy with ultraviolet B (UV-B) radiation and photochemotherapy with psoralen plus ultraviolet A (UV-A; PUVA) are highly effective treatment modalities for psoriasis. However, PUVA is considered therapeutically superior to UV-B phototherapy. The narrowband UV-B lamp provides faster clearing, fewer burning reactions and longer periods of remission than conventional broadband UV-B phototherapy. Tanew and colleagues compared the therapeutic efficacy of narrow-band UV-B phototherapy with that of PUVA treatment in chronic plaque-like psoriasis.

Patients with chronic plaque-like psoriasis were eligible for this nonrandomized, open-paired comparison study. Patients rated the severity of their psoriasis using the Psoriasis Area and Severity Index (PASI) at baseline and at the end of the study. Patients received paired irradiations with narrowband UV-B and PUVA (half-side comparison) to the dorsal aspect of the entire body, including the extremities. As the patient's right side was irradiated with narrowband UV-B, the left side was covered with four layers of cotton to prevent transmission of UV light. One hour later, the left side was exposed to PUVA while the right side was shielded in the same manner. Treatments were given three times a week, up to a maximum of 18, until complete or almost-complete clearing with one or both regimens occurred.

Twenty-one patients completed the study. Overall, the response to PUVA treatment was slightly better than that to narrowband UV-B phototherapy. Median baseline PASI scores were reduced by 84 percent for patients receiving narrowband UV-B phototherapy and 89 percent for those receiving PUVA treatment. When patients were stratified according to their pretreatment PASI scores, the correlation to treatment response was significant. With increasing PASI scores, the patients' psoriasis cleared better with PUVA treatment than with narrowband UV-B phototherapy. Patients with lower pretreatment PASI scores had greater reduction in PASI scores and a higher probability of clearing completely within the study period no matter what treatment modality was used. Side effects to treatment were minimal with only minor nausea and pruritis reported.

The authors conclude that narrowband UV-B phototherapy should be considered first-line treatment for patients with moderate to severe plaque-like psoriasis, as it appears to be as effective as PUVA treatment in these patients. However, this study showed a positive correlation between the magnitude of the baseline PASI score and the probability that lesions would clear better with PUVA treatment in patients who are more severely affected. Therefore, PUVA treatment should remain the mainstay in patients with severe psoriasis whose symptoms do not respond to or cannot be controlled adequately by narrowband UV-B phototherapy.