title: The role of a placebo-treated control group in combination drug trials.
abstract: In order to satisfy regulatory requirements for fixed-dose combination drug products, clinical trials must demonstrate that each component contributes to the claimed effect of the combination. Thus, the comparisons of primary interest are usually of the combination versus combination minus one component, and do not involve placebo. However, a placebo-treated group can be useful for interpreting the primary comparisons and for clarifying the nature of effects in the presence of interactions. These points are illustrated by examples from various drug classes. Statistical analysis of combination drug trials, particularly the appropriateness of factorial analysis, is also discussed.
authors.affiliation: Technical Information Section, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20892.
authors.forename: G
authors.initials: G
authors.lastname: Pledger
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods*; D004338:Drug Combinations / Q000627:therapeutic use*; D004347:Drug Interactions; D006801:Humans; D010919:Placebos / Q000627:therapeutic use*; D012107:Research Design; D013223:Statistics as Topic
chemical_list: D004338:Drug Combinations; D010919:Placebos