Evolution of antiseizure medication use and cost in the United States of America 2006-2021

Objective: To describe the evolution in use and cost of antiseizure medications (ASM) in the United States of America (USA).Methods: Retrospective descriptive study using the IBM MarketScan Commercial Database (data of privately -insured patients) for the years 2006 to 2021. We identified patients with epilepsy who were on ASM. We adjusted cost for inflation with the Gross Domestic Product Implicit Price Deflator.Results: We evaluated 347,158 patients (46.9 % males; median (p25-p75) age: 33 (17-49) years; 28 % with pediatric-onset epilepsy and 72 % with adult-onset epilepsy) with a total of 1,385,382 person-years and 588,285,065 ASM prescription days. The most commonly prescribed (as percentage of prescription days) ASMs in 2006 were valproate (18 %) and lamotrigine (17 %) in pediatric-onset epilepsy and phenytoin (21 %) and carbamazepine (17 %) in adult-onset epilepsy, but starting in the 2010s, levetiracetam and lamotrigine became the most commonly prescribed ASMs in both pediatric-onset (in 2021, levetiracetam 25 %, lamotrigine 16 %) and adult-onset (in 2021, levetiracetam 27 %, lamotrigine 20 %) epilepsy. The proportion of generic ASM use increased 3.6-fold: from 23 % of prescription days in 2006 to 83 % of prescription days in 2021. The median (p25 -p75) average wholesale price (AWP) per person-year increased by 102 % from $2,684 ($990-$5,509) in 2006 to $5,417 ($2,858-$12,310) in 2021. The increases were greater in absolute terms for brand-name ASMs by 419 %: $3,109 ($1,564-$5,068 in 2006 and $16,149 ($12,950-$23,377) in 2021 than for generic ASMs by 462 %: $699 ($457-$1,678) in 2006 and $3,931 ($2,618-$6,081) in 2021. The costs directly borne by the patient (copay, coinsurance, deductibles, and pharmacy processing fees) increased by 69 % for brand-name ASMs from $393 ($246-$570) in 2006 to $665 ($335-$1,308) in 2021, but decreased by 37 % for generic ASMs from $147 ($98-$213) in 2006 to $92 ($51-$141) in 2021.Conclusions: The median cost of ASMs per person-year approximately doubled from 2006 to 2021. The increase in use of generic ASMs probably helped buffer the growing costs of ASMs. However, generic ASMs already represent 83 % of prescription days in 2021, with limited room to further contain costs by just increasing the proportion of generics.