Vehicle or placebo? Investigators use incorrect terminology in randomized controlled trials half of the time: a systematic review of randomized controlled trials published in three major dermatology journals.

A topical comparison in a randomized controlled trial (RCT) should correctly be termed a vehicle rather than a placebo as the vehicle in a dermatologic drug product enhances delivery and efficacy of the active compound.To conduct a systematic review of RCTs involving topical drugs published in the Archives of Dermatology, Journal of the American Academy of Dermatology and British Journal of Dermatology for correct classification of studies as vehicle versus placebo-controlled.RCTs involving topical drugs published in the Archives of Dermatology, Journal of the American Academy of Dermatology and British Journal of Dermatology from January 1999 to November 2008 were identified through PubMed, supplemented by citation lists from the individual journals' web pages. Only original studies that involved using a topical control or used the term topical "vehicle" or "placebo" were selected. The studies were examined for correct classification as vehicle-controlled, the year of publication, country of origin, sample size, funding source and nature of study center.Out of 132, 64 (49%) correctly classified their studies as vehicle-controlled. Pharmaceutical-funded studies (55%, P=0.01) were significantly associated with the use of correct classification.As only three peer-reviewed dermatology journals were studied, findings may not be generalized to other dermatology journals and other types of publications.This systematic review highlights a common pitfall in the reporting of studies of topical dermatology drugs.