That was one of the findings of a new study examining patterns of antiseizure medication (ASM) usage in the Human Epilepsy Project (HEP).
Vanderbilt University Medical Center–led researchers pointed out that slightly more than one-third of focal epilepsy patients remain on monotherapy with their first prescribed ASM. In addition, approximately three in five patients transition to monotherapy with another ASM while approximately two in five end up on polytherapy.
In an article published in Epilepsia, researchers described their efforts to ascertain the natural history and patterns of ASM use in newly diagnosed focal epilepsy patients who were initially started on monotherapy.
The study team analyzed data from the HEP, assessing differences between the durations of the most commonly first–prescribed ASM monotherapies using a Cox proportional hazards model. Three groups were created with patients on monotherapy, sequential monotherapy, and polytherapy.
The 443 patients included in the analysis had a median age of 32 years (interquartile range [IQR] 20-44) and a median follow-up time of 3.2 years (IQR 2.4-4.2). Of those, 161 (36.3%) patients remained on monotherapy with their initially prescribed ASM at the time of their last follow-up. The researchers reported that the mean (SEM) and median (IQR) duration of time that patients stayed on monotherapy with their initial ASM was 2.1 (2.0-2.2) and 1.9 (0.3-3.5) years, respectively.
The most commonly prescribed initial ASM was levetiracetam (254, 57.3%), followed by lamotrigine (77, 17.4%), oxcarbazepine (38, 8.6%) and carbamazepine (24, 5.4%), according to the researchers.
Of those who did not remain on the initial monotherapy, 167 (59.2%) transitioned to another ASM as monotherapy (sequential monotherapy) and 115 (40.8%) ended up on polytherapy, according to the report. Interestingly, the authors noted, patients remained significantly longer on lamotrigine (mean: 2.8 years, median: 3.1 years) compared with levetiracetam (mean: 2.0 years, median: 1.5 years) as a first prescribed medication (hazard ratio 1.5; 95% CI, 1.0-2.2).
“As the study progressed the proportion of patients on lamotrigine, carbamazepine and oxcarbazepine as well as other sodium channel agents increased from a little more than one-third (154, 34.8%) of patients to more than two-thirds (303, 68.4%) of patients,” the researchers wrote.
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