Study M03-658 was a continuation study for participants with moderate to severe psoriasis who had participated in a prior psoriasis adalimumab study. Study M03-658 consisted of three sequential treatment periods. The first period was Period O, in which participants received open-label treatment with adalimumab (40 mg every other week or 40 mg every week) for a minimum of 104 weeks and a maximum of 252 weeks. Period O was the only period of the study until May 2008, when the subsequent periods were added via amendment to the protocol. At that time, participants who had achieved satisfactory therapeutic response (a Physician's Global Assessment \[PGA\] of 0, 1, or 2 \[clear, minimal, or mild\]) were given the opportunity to discontinue from the study or to continue and participate in the subsequent two periods. The second period was Period W, a maximum of 52 weeks, in which participants with a PGA of 2 (mild) or less were withdrawn from adalimumab treatment (i.e., participants received no treatment) until relapse of their psoriasis occurred (defined as a PGA of 3 \[moderate\] or worse). The third period was Period R, a 16-week period in which participants were retreated with open-label adalimumab (80 mg initial dose followed by 40 mg every other week). Period O was designed to evaluate the first objective regarding long-term efficacy and safety of adalimumab treatment, and Period R was designed to evaluate the effectiveness of adalimumab retreatment following relapse. Specific subsets of the study population that were identified as the populations of interest were the modified intent-to-treat populations for Period W and Period R, and these are described further in the outcome measures.
