In the study titled "An International Randomized, Double-blind, Placebo-Controlled Phase 3 Trial of Intramuscular Alefacept in Patients With Chronic Plaque Psoriasis," by Lebwohl et al,1 and the corresponding editorial comments by Dr Gottlieb,2 much is made of the "durability" of the response to alefacept (Amevive; Biogen Inc, Cambridge, Mass), while the durability of the response to placebo is ignored. Extrapolating the numbers from Figure 3 in the article shows that 42% of patients who received 15 mg of alefacept for 12 weeks achieved a reduction of at least 50% in the Psoriasis Area Severity Index (PASI) score. The improvement was maintained for 12 weeks after therapy in 71% of the patients. Although this "durable," or long-lasting, response of 71% may appear impressive, the corresponding number for the placebo group was 90% (17% showed 50% reduction in the PASI score, and 90% maintained this improvement 12 weeks later).
Whitmore SE. Appropriate Use of Alefacept Therapy for Psoriasis—Reply. Arch Dermatol. 2004;140(2):239-240. doi:10.1001/archderm.140.2.239