Trends in Antiseizure Medication Initiation, Switch, or Termination in Patients With Newly Diagnosed Epilepsy: A Nationwide Study.

Background And Objectives: Few studies evaluate physicians' choice of antiseizure medication (ASM) to treat patients with newly diagnosed epilepsy. The objective of this study was to analyze the choice of ASM and its use by age, sex, psychiatric comorbidities, and concurrent treatment with other drugs (antidepressant medications and contraceptives) in patients who initiated epilepsy treatment using monotherapy.

Methods: Included in this study were persons (any age) with an incident hospital diagnosis of epilepsy during 2010-2022 in the Swedish Patient Register (SPR), preceding a first dispensing of any ASM (as reported in the Swedish Prescribed Drug Register, SPDR) for the period 2010-2022. Incident patients were identified using retrospective information during 2000-2009 in the SPR. Primary outcome was first dispensed ASM by age, sex, comorbidity, and comedication with antidepressants or contraceptives (SPDR). Secondary outcomes were time to ASM switch or termination assessed by survival analyses.

Results: Of 67,984 patients included (mean age 46; 46% female), 66,441 initiated ASM treatment using monotherapy. Relative risk (RR) for initiating treatment using monotherapy did not differ between age groups, sex, or patients with concurrent treatment with antidepressants, contraceptives, or psychiatric illness (RR and 95% CI did include 1.0). The share initiating treatment using levetiracetam increased from 10% in 2010 to 55% in 2022; valproic acid: 10%-5%. The likelihood of initiating treatment using 1 of the 5 most frequent ASMs differed between all compared groups (0.3 < RR < 1; 95% CI < 1; 1 < RR < 15; 1 <95% CI). Seven percent of female patients of childbearing age initiated treatment with valproic acid, levetiracetam was the most frequent initial ASM in patients with psychiatric comorbidity (40.2%), and lamotrigine the most prescribed initial ASM to women on contraceptives (50.4%). Highest likelihoods of treatment termination were found among children (1.72 < RR < 3.07; 1 <95% CI) and among patients with psychiatric comorbidity (initiated on carbamazepine, RR 1.38; 1 <95% CI or lamotrigine, RR 1.31; 1 <95% CI). Thirty-one percent to 47% of patients switched from an initial monotherapy to a new monotherapy within 5 years. Twenty percent to 42% terminated ASM treatment within 5 years.

Discussion: Levetiracetam and lamotrigine were the most frequently dispensed initial ASMs, also among patients with comorbidities or comedications complicating the use of these ASMs, highlighting the need for improved education of prescribers concerning ASM selection in relation to individual patient characteristics. Use of ASMs in hospital is not captured in the SPDR.