Abstracts

Rationale: Depression is a common comorbidity among patients with drug-resistant epilepsy (DRE); it also is independently associated with relatively high levels of use and cost of healthcare services and pharmacotherapy. Neurostimulation (i.e., vagus nerve stimulation [VNS], responsive neurostimulation [RNS], deep brain stimulation [DBS]) is an option for patients with seizures refractory to treatment by anti-seizure medications (ASMs). The degree to which neurostimulation may impact depression-related care is not well understood.

Methods: Relevant procedure codes were used to identify patients with epilepsy in a large US healthcare claims database who underwent a neurostimulation procedure any time between 2012 and 2019. The earliest date on which neuromodulation was identified during this period was designated the index date. Patients without a diagnosis of epilepsy on index date, those without claims for ASMs in the year prior, and those not enrolled for the 2-year period prior to index were excluded. Patients were allocated to one of two cohorts based on index procedure (VNS Cohort, RNS/DBS Cohort). Propensity scores were generated using demographic and clinical characteristics (including depression and healthcare use) during the 2 years prior to index, and used to match the cohorts. All medical claims with diagnoses of depression, and all antidepressant dispenses, were deemed depression-related. Use and cost of healthcare services and pharmacotherapies were assessed over the 12- and 24-month periods following index date. For categorical variables, the statistical significance of differences between cohorts was assessed with McNemar’s tests; for continuous measures, paired t-tests and Wilcoxon signed-rank tests, as appropriate, were used.

Results: A total of 836 patients met selection criteria (310 VNS; 526 RNS/DBS), and 179 VNS patients were matched to an equal number of RNS/DBS patients. In the VNS cohort 30% of patients had evidence of depression during the 2-year period prior to index date, as did 32% of their matched counterparts in the RNS/DBS cohort (standardized difference=-0.065). Patients with VNS were approximately one-third as likely as those who received RNS/DBS to experience depression-related hospitalizations 12 months (3.4% vs. 14.0%; P< 0.001) and 24 months (4.5% vs. 15.6%; p< 0.001) post-index. Mean (SD) depression-related costs among patients in the VNS Cohort were about one-fourth those of patients in the RNS/DBS Cohort at 12 months ($5,240 [$35,872] vs. $22,970 [$78,083]; p=0.0156) and 24 months ($5,656 [$36,104] vs. $24,228 [$79,543]; p=0.0145).