Patient Nonadherence in Clinical Trials: Could There Be a Link to Postmarketing Patient Safety?

Patient nonadherence is one of the most complex problems facing clinical investigators. It not only affects clinical trial results but also could affect the clinical efficacy and safety of a medication after it has been approved for usage in the general population. Research shows that up to 30% of clinical trial participants may be discarding their study medications prior to study visits. Undetected poor adherence can result in overestimation of the dosage and underestimation of the adverse event profile. Patients in the general population will be at risk if they take the study dose but have a higher rate of patient adherence than the study participants in the clinical trial. This becomes an issue if patients after the launch receive more effective patient education than study participants in clinical trials and are more adherent. Several interventions to increase study participant adherence are recommended. The goal of study investigators should be to reach a high clinical trial participant adherence level that will not require an increase in sample size to maintain power of the study. This will give health professionals assurance that patient safety is not in danger because the dose and adverse event profile would be based on a higher level of patient adherence than would be expected in the general population after the launch.