Is regular epilepsy drug level monitoring really useful in pregnancy?

AntiEpileptic drug Monitoring in PREgnancy (EMPiRE): a double-blind randomised trial on effectiveness and acceptability of monitoring strategies.

Thangaratinam S, Marlin N, Newton S, et al.

Health Technol Assess 2018; 22:1-152.

Abstract

BACKGROUND:

Pregnant women with epilepsy on antiepileptic drugs (AEDs) may experience a reduction in serum AED levels. This has the potential to worsen seizure control.

METHODS:

To determine if, in pregnant women with epilepsy on AEDs, additional therapeutic drug monitoring reduces seizure deterioration compared with clinical features monitoring after a reduction in serum AED levels. A double-blind, randomised trial nested within a cohort study was conducted and a qualitative study of acceptability of the two strategies was undertaken. Stratified block randomisation with a 1 : 1 allocation method was carried out.  Pregnant women with epilepsy on one or more of the following AEDs: lamotrigine, carbamazepine, phenytoin or levetiracetam. Women with a ≥ 25% decrease in serum AED level from baseline were randomised to therapeutic drug monitoring or clinical features monitoring strategies. In the therapeutic drug monitoring group, clinicians had access to clinical findings and monthly serum AED levels to guide AED dosage adjustment for seizure control. In the clinical features monitoring group, AED dosage adjustment was based only on clinical features.

RESULTS:

A total of 130 women were randomised to the therapeutic drug monitoring group and 133 to the clinical features monitoring group; 294 women did not have a reduction in serum AED level. A total of 127 women in the therapeutic drug monitoring group and 130 women in the clinical features monitoring group (98% of complete data) were included in the primary analysis. There were no significant differences in the time to first seizure (HR 0.82, 95% CI 0.55 to 1.2) or timing of all seizures after randomisation (HR 1.3, 95% CI 0.7 to 2.5) between both trial groups. In comparison with the group with stable serum AED levels, there were no significant increases in seizures in the clinical features monitoring (odds ratio 0.93, 95% CI 0.56 to 1.5) or therapeutic drug monitoring group (odds ratio 0.93, 95% CI 0.56 to 1.5) associated with a reduction in serum AED levels. Maternal and neonatal outcomes were similar in both groups, except for higher cord blood levels of lamotrigine (MD 0.55 mg/l, 95% CI 0.11 to 1 mg/l) or levetiracetam (MD 7.8 mg/l, 95% CI 0.86 to 14.8 mg/l) in the therapeutic drug monitoring group than in the clinical features monitoring group. There were no differences between the groups on daily AED exposure or quality of life. An increase in exposure to lamotrigine, levetiracetam and carbamazepine significantly increased the cord blood levels of the AEDs, but not maternal or fetal complications. Women with epilepsy perceived the need for weighing up their increased vulnerability to seizures during pregnancy against the side effects of AEDs.

CONCLUSION:

There is no evidence to suggest that regular monitoring of serum antiepileptic drug levels in pregnancy improves seizure control or affects maternal or fetal outcomes.

This assessment is cited in the neurochecklist:

Antiepileptic drugs (AEDs) in pregnancy

Abstract link

By Mikael Häggström, M.D.Author infoReusing imagesWritten informed consent was obtained from the individual, including online publication. – Own work, CC0, Link

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