March 16, 2022

Antiseizure Medication Treatment Pathways in US Medicare Beneficiaries with Newly Treated Epilepsy

Abstract found in Wiley Online Library


Objective: To characterize antiseizure medication (ASM) treatment pathways in Medicare beneficiaries with newly treated epilepsy.

Methods: This was a retrospective cohort study using Medicare claims. Medicare is the US’s federal health insurance program for people aged 65 and older plus younger people with disabilities or end-stage renal disease. We included beneficiaries with newly treated epilepsy (International Classification of Diseases codes for epilepsy/convulsions 2014-2017, no ASM in the previous two years). We displayed the sequence of ASM fills using sunburst plots overall, then stratified by mood disorder, age, and neurologist prescriber. We tabulated drug costs for each pathway.

Results: We included 21,458 beneficiaries. Levetiracetam comprised the greatest number of pill days (56%), followed by gabapentin (11%) and valproate (8%). There were 22,288 unique treatment pathways. The most common pathways were levetiracetam monotherapy (43%), gabapentin monotherapy (10%), or valproate monotherapy (5%). Gabapentin was the most common second- and third-line ASM. Whereas only 2% of pathways involved first-line lacosamide, those pathways accounted for 19% of cost. Gabapentin and valproate use was increased and levetiracetam use was decreased in beneficiaries with mood disorders compared to beneficiaries without mood disorders. Levetiracetam use was increased and gabapentin, valproate, lamotrigine, and topiramate use was decreased in beneficiaries aged over 65 compared with those aged 65 or less. Lamotrigine, levetiracetam, and lacosamide use was increased and gabapentin use was decreased in beneficiaries whose initial prescriber was a neurologist compared to those whose prescriber was not a neurologist.

Significance: Levetiracetam (Keppra) monotherapy was the most common pathway, though substantial heterogeneity existed. Lacosamide (Vimpat) accounted for a small percent of anti-seizure medications (ASMs) but a disproportionately large share of cost. Neurologists were more like to prescribe lamotrigine (Lamictal) compared with non-neurologists, and lamotrigine was prescribed far less frequently than may be endorsed by guidelines. Future work may explore patient- and physician-driven factors underlying ASM choices.