Lamotrigine Blood Levels Did Not Predict Seizures In Pregnancy

What was studied

Researchers looked at whether repeated blood levels of lamotrigine during pregnancy were associated with seizure occurrence during pregnancy or up to 6 weeks after birth, and whether these serial measurements improved prediction of seizure risk beyond baseline clinical factors.

This was a secondary analysis of the UK EMPiRE study, which involved 50 maternity units. The analysis included 183 pregnant women with epilepsy who were taking lamotrigine, either alone or with other seizure medicines, and who had a baseline blood test plus at least one follow-up lamotrigine level measured before a seizure or by 6 weeks postpartum.

What they found

In this group, 46 women had seizures during pregnancy. The researchers did not find evidence that changes in lamotrigine blood levels over time were associated with seizure occurrence. A prediction model using these repeated lamotrigine levels had poor discrimination, with AUC values ranging from 0.46 to 0.55 during pregnancy.

The baseline daily lamotrigine dose was the only independent predictor of seizure risk in this analysis. Overall, the study suggests that serial lamotrigine blood levels do not appear to predict seizure occurrence in pregnancy.

Limits of the evidence

This study was a secondary analysis, so it used data collected for a broader trial rather than a study designed only for this question. Only 183 of the 560 women in the EMPiRE study were included in this analysis, and 46 had seizures, which limits certainty.

The results do not show that lamotrigine blood testing has no value for treatment decisions; they only suggest that repeated levels did not improve seizure risk prediction in this dataset.

For families and caregivers

Lamotrigine levels often fall during pregnancy, and blood tests are sometimes used to help adjust the dose. In this study, repeated lamotrigine blood levels did not appear to predict whether seizures would happen during pregnancy.

For families, this suggests that seizure risk in pregnancy may not be predicted well by lamotrigine blood levels alone.

What to watch next

Further studies could assess whether lamotrigine blood levels add useful information for predicting seizure risk beyond baseline clinical factors and medication dose.

Terms in this summary

lamotrigine

A medicine used to help prevent seizures.

serum concentration

The amount of a medicine measured in the blood.

biomarker

A measurable sign in the body that may help predict a health outcome.

secondary analysis

A new analysis of data that were already collected in an earlier study.

hazard ratio

A number researchers use to compare how often an event happens over time in one group versus another.

AUC

A score showing how well a prediction model separates people who will have an outcome from those who will not; closer to 1 is better, and 0.5 is about no better than chance.

postpartum

The period after giving birth.