Estimating the power of compliance-improving methods.
Measuring patient compliance with prescribed or protocol-specified regimens of drug administration is an important topic in clinical trial research. One of the most useful expressions of compliance is the proportion of days the prescribed dose was taken correctly, but the distribution of this variable is often bimodal. We show that a two-component mixture of beta distributions can be fitted to these data. The two components can be interpreted as the groups of poorly and satisfactorily complying patients, respectively. This representation was helpful in the calculation of the power in a recent trial of a method to improve the compliance of patients with a lipid-lowering drug regimen. Control Clin Trials 2000;21:540-551
Lesaffre
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Biostatistical Centre, Leuven, Belgium. emmanuel.lesaffre@med.kuleuven.
de Klerk
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D015982:Bias; D002986:Clinical Trials as Topic; D004334:Drug Administration Schedule; D006801:Humans; D000960:Hypolipidemic Agents / Q000008:administration & dosage; D008433:Mathematics; D010349:Patient Compliance; D018709:Statistics, Nonparametric
D000960:Hypolipidemic Agents