Biologic therapies for moderate to severe psoriasis are not interchangeable

Health care managers and hospital pharmacists are increasingly compelling prescribers to use medication substitutes. This policy becomes particularly evident when the agents are biologics with shared indications based on their assumed clinical equivalence and efficiency (cost-effectiveness), and in these cases the involvement of clinicians in decision making is often minimal or nonexistent. Lacking head-to-head clinical trials comparing various drugs, the prescriber can use indirect comparisons to define 2 or more agents as clinically equivalent therapeutic alternatives. This denomination of clinical equivalence does not imply that 2 such medications are truly therapeutically equivalent, or therapeutic equivalents, as this type of equivalence is defined by the absence of statistically significant differences between the drugs on all measures of effect in most patients, meaning that neither one is preferable to the other in different situations. Although real patients are not entirely comparable to those in clinical trials, the choice of a biologic agent to treat psoriasis is largely based on the findings of such trials. A recently published meta-analysis shows that not all the biologics currently available to treat moderate to severe psoriasis can be considered therapeutic equivalents, in spite of the authors' claim to the contrary; indeed, infliximab and etanercept can in no way be considered equivalent therapeutic alternatives based on the data provided. Biologics do display real differences with respect to efficacy at different time points and in the time required to onset of effect. In any case, therapeutic decisions should be made by an experienced clinician and tailored to each individual patient.