Pharmaceutical Medicine

, Volume 23, Issue 5–6, pp 289–297 | Cite as

Strategies to Measure and Improve Patient Adherence in Clinical Trials

Review Article


Investigators conducting clinical trials need to appreciate the important role of adherence in clinical research. Poor compliance may reduce the power of a study and lead to an underestimation of the efficacy of a treatment and dismissal of a potentially useful therapeutic agent. In general, medication adherence of participants in clinical trials is better than in clinical practice. The study protocol should indicate how adherence will be handled, both in terms of measurement and in the data analysis. Unfortunately, no perfect method for assessing compliance exists, complicating research in this area. Techniques commonly employed in research include self-reporting (such as diaries), pill counts and electronic monitors with a combination of methods preferred. Selection of which method(s) to use will depend on the goals of the study, the type of noncompliance of interest and the resources available. When designing a clinical trial, interventions to facilitate optimal adherence should be considered. One strategy to attempt to minimize the number of study subjects who will be poor adherers is to attempt to identify these individuals and eliminate them using a runin period. Study participants should be well informed and expectations with respect to study procedures should be realistic. Factors that affect compliance should be taken into account in drug development in an effort to improve medication-taking behaviour. Drugs with less frequent dosing to enhance patient convenience or fixed-dose combination drugs to reduce the pill burden are possible options, as is the use of specialized containers and packaging. Newer technologies such as ‘smart’ pill boxes and text messaging offer promise; however, further research into their usefulness and patient acceptance needs to be undertaken. This article will provide an overview of patient adherence with drugs in the clinical trial setting including factors that affect patient adherence, methods to monitor adherence and strategies to minimize the barriers to adherence, including the use of newer technologies.


Medication Adherence Text Messaging Interactive Voice Response Pill Count Medication Event Monitoring System 



No sources of funding were used to assist in the preparation of this review. The author has no conflicts of interest that are directly relevant to the content of this review.


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Copyright information

© Adis Data Information BV 2009

Authors and Affiliations

  1. 1.Departments of Paediatrics and Medicine, Children’s Hospital, London Health Science CentreUniversity of Western OntarioLondonCanada

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