Rates of serum level determinations of antiepileptic drugs in accord with guidelines: A clinical study at a tertiary center.

OBJECTIVE: To compare our rates of appropriate therapeutic drug monitoring (TDM) with those defined in the French guidelines for measuring drug levels of antiepileptic drugs (AEDs) during the pre- and post-medical/pharmaceutical interventional periods.

METHODS: This study was prospectively carried out at a tertiary center (epilepsy unit of the Pitié-Salpêtrière Hospital in Paris) between 2013 and 2016 over three time periods. Criteria for appropriateness were those stated in the current French guidelines. The main outcome measure was the percentage of drug level measurements with an appropriate indication, while a second outcome measure was the impact of education on clinical practice.

RESULTS: Of the 698 AED level measurements requested, 84% overall were found to have appropriate indications ranging from 75% to 90%, according to French guideline criteria. Rates of appropriate indications for the three most commonly used individual AEDs-valproate, carbamazepine and lamotrigine-were 79.6%, 77.3% and 90.7%, respectively, whereas the requests considered to not have an appropriate indication involved the majority (63.5%) of cases of routine drug monitoring. In addition, dedicated education seems to substantially increase rates of appropriateness.

CONCLUSION: At our center, 84% of AED level determinations had an appropriate indication according to a priori defined and reliable criteria. Moreover, it was noted that a specific educational intervention substantially increased rates of appropriateness. Thus, it appears to be crucial to ensure that medical and paramedical staff are aware of the official recommendations to avoid taking unnecessary drug level measurements.