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.