Measuring non-adherence — FAQ

While highly objective, biochemical tests have major practical drawbacks. They are expensive, invasive, and time-consuming. Crucially, they typically only detect recent use, so a patient could take their medication just before the test ('white-coat adherence') and appear fully compliant, masking long-term non-adherence. Therefore, they are usually reserved for research or specific clinical situations, not routine monitoring.

It is more reliable than self-report because it is an objective measure, but it has a significant flaw. It can only confirm that the medication is no longer in the container; it cannot confirm that the patient actually ingested it. Patients can easily manipulate the results by 'pill dumping'—throwing away pills to make it seem like they have taken them. So, while it provides some objective data, it is not a foolproof measure of true adherence.

Simply asking the patient is a form of self-report, and while it is a necessary part of the doctor-patient conversation, it is not a reliable method for measuring adherence. The relationship dynamic can lead patients to give socially desirable answers—they want to be seen as a 'good patient' and may not admit to non-adherence. They may also genuinely forget or misremember how often they have missed doses (recall bias). Therefore, more objective methods are needed for accurate clinical assessment and research.