Single antiepileptic drug levels do not predict adherence and non-adherence.

"Subtherapeutic" AED Plasma levels only rarely are caused by non-adherence whereas levels in the "therapeutic range" by no means prove that the patient is adherent to treatment. For meaningful interpretation, any level needs to be compared with other levels of the same patient. Our findings strongly emphasize the principle of individualized therapeutic AED monitoring as promoted by the Therapeutic Strategies Commission of the ILAE. This article is protected by copyright. All rights reserved.