Normalization and cross-sectional validation of an extended Adverse Event Profile (E AEP) in a large cohort of patients with epilepsy

Purpose: The Liverpool Adverse Event Profile (L AEP) is commonly used in clinical practice and pharmacological trials for the monitoring of side effects of anti-seizure medication (ASM). However potentially unrelated, additional symptoms and normative data should be considered to put patients´ complaints into perspective.

Methods: An extended 32-item AEP (E AEP) was given to 537 healthy subjects and 1,605 patients with epilepsy as part of the Bonn ASM side effect registry. The tool was factor-analyzed, corrected for age, gender, and repeated application, and related to drug load and individual substances (with N> 100) on item and scale level (total E AEP and its subscales cognition, dizziness, energy, mood, bodily symptoms, aggression, and sexuality).

Results: Compared to non-normalized results, at item level, between one and two-thirds of responses suggesting impairment were found to be unlikely to be related to ASM treatment after normalization. Binary regression analyses revealed differential effects of medication choice, but also of antidepressants and neuroleptics on complaint domains. The explained variance was better for physical than psychological domains. The results reflect both known drug side effects and indications. Patients´ explicit attribution of problems to their medications barely improved the correlation of the E AEP and treatment parameters.

Conclusion: Application of a norm-referenced AEP is highly recommended to avoid overestimation of treatment related problems in patients with epilepsy. It allows evaluation on item and scale level for individuals as well as groups in drug trials. Plausible relations to individual drugs and to drug load can be demonstrated. The explanatory power was better for physical than psychological domains. Drug-related complaint patterns reflect known drug side effects (e.g. perampanel and brivaracetam with aggression) as well as drug indications (e.g. lamotrigine for depression). This is likely to be particularly relevant when side effects may have affected treatment decisions. Longitudinal evaluation with repeated application of the E AEP with changes of drug treatment is in progress.