Abstracts

Rationale: VNS is an adjunctive therapy to antiepileptic drugs (AEDs) in patients 12 years or older with refractory partial-onset seizures that are not controlled with medication alone. The purpose of this study was to evaluate the clinical and economic benefits associated with VNS Therapy in pediatric patients with refractory epilepsy in a real-world setting.Methods: A retrospective cohort study design was applied, using data from 5 Medicaid State claims databases (01/97-06/09), including Florida, Iowa, Kansas, Missouri, and New Jersey. Pediatric patients aged 17 years and younger receiving VNS who had ?1 neurologist visit with a diagnosis of epilepsy (ICD-9 345.xx, 780.3, or 780.39), ?1 medical procedure claims for VNS implantation, ?1 AED dispensing, and ?6 months of pre- and post-VNS health plan continuous enrollment were included. The pre-VNS period was defined as the 6-month period preceding the first VNS implantation date (index date), while the post-VNS period spanned from the index date until the earliest of the VNS removal, death, end of enrollment, or data end date. Patients' observation period was divided into 90-day intervals (i.e. quarters) and outcomes were repeatedly measured at each quarter. Morbidity outcomes were measured by frequency of hospitalizations, hospital length of stay, emergency room (ER) visits, outpatient visits, neurologist visits, fractures, head injuries, and status epilepticus events. Univariate and multivariate Poisson regression models were used to estimate the incidence rate ratios (IRR) of the morbidity outcomes between the pre- and post- VNS periods. Univariate and multivariate regression models were also used to estimate the total healthcare cost difference (quarterly) between the pre- and post- VNS period.Results: Of the 445 patients meeting the inclusion criteria, 238 were aged between 1-11 years and 207 were between 12-17 years. For patients aged 1-11 years, hospitalizations, hospitalization days and ER visits were reduced during post-VNS versus pre-VNS period (adjusted IRR= 0.73 [CI: 0.61-0.88], IRR=0.75 [CI: 0.68-0.82] and IRR=0.74 [CI: 0.65-0.83], respectively). Average total healthcare costs were numerically lower during post-VNS versus pre-VNS period ($17,831 versus $18,220 quarterly [p=0.052]). For patients aged 12-17 years, hospitalizations, hospitalization days and ER visits were reduced during post-VNS versus pre-VNS period (adjusted IRR= 0.43 [CI: 0.34-0.54], IRR=0.52 [CI: 0.47-0.57], and IRR=0.44 [CI: 0.39-0.51], respectively). Average total healthcare costs were lower during post-VNS versus pre-VNS period ($14,068 versus $19,047 quarterly [p=.002]). Conclusions: Based on a sample of 445 pediatric patients, VNS was associated with decreased healthcare resource utilization and epilepsy-related events, such as hospitalizations, hospitalization days, and ER visits, resulting in net cost savings for public payers.