Physician and patient adherence in hypertension trials: a point of view on an important issue to resolve.

Randomized controlled trials (RCTs) are important sources of evidence that strongly influence guidelines for patient management, including for elevated blood pressure in adults. Critical questions regarding the interpretation of hypertension trial results have recently increased, especially for concerns over methodology. In particular, investigator adherence to the protocol and patient adherence to investigational drugs are often far from optimal. These issues may be ignored or underreported because physicians' behavior during trials is often not monitored and patients' medication adherence is neither measured adequately nor reported or analyzed in the final report or in the publication. This situation may lead to misinterpretations of study results and misevaluations of the safety and efficacy profile of new drugs. In this short review, the problem of measuring, reporting, and analyzing drug adherence in RCTs is discussed and illustrated with several examples in the field of hypertension. The main conclusion is that drug adherence should always be measured in clinical trials, possibly with more than one method. In addition, prespecified analyses of adherence data should be included in the statistical plan of all trials to improve their overall quality.