Adherence measures and their utility

Abstract

This article addresses the variety of adherence measures available to the researcher, with particular reference to the utility of markers. It is proposed that the generic nature of the research question will suggest both the adherence definition and the appropriate assessment methodology. Each measurement procedure offers somewhat different information and has unique advantages and disadvantages. It is suggested that markers are limited by the relatively short duration of the measurement period, the lack of quantitative data on adherence, and, with some, the potential for confounding influences on their specificity. The probable value of markers lies in validating the subject's recent self-report, determining recent medication ingestion, and estimating the probability of adherence over time.