Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved. BACKGROUND: With the advent of biologic drugs in the management of moderate to severe psoriasis, there may have been a shift in therapeutic approach from rotational strategies to a unidirectional progression from topical treatments to the highest rung of the therapeutic ladder. We studied the frequency of switching from classic to biologic therapy and vice versa in a cohort of patients with psoriasis over a period of up to 5 years.METHODS: Patients are included in the BIOBADADERM prospective registry when they are first prescribed any specific conventional or biologic systemic treatment. The data for each patient refer to the follow-up period from the time they entered the cohort until October 2013. To describe the pattern of switches from classic to biologic therapy and vice versa, we used the data in the registry on the first day of every 365-day period following the date each patient was included in the cohort.RESULTS: In total, 47.3% of the patients (926/1956) were prescribed a classic systemic drug and 52.7% (1030/1956) a biologic agent on entry into the study. Of the 741 patients who accumulated 5 years of follow-up, 21.9% (155) were receiving nonbiologic drugs and 78.1% (553) were on biologic therapy on the first day of their 5th year of follow-up.CONCLUSIONS: The proportion of patients receiving biologic therapy increased with longer follow-up.