Clinical and economic impact of vagus nerve stimulation therapy in patients with drug-resistant epilepsy.

We evaluated long-term medical and economic benefits of vagus nerve stimulation (VNS) therapy in drug-resistant epilepsy. A pre-post analysis was conducted using multistate Medicaid data (January 1997-June 2009). One thousand six hundred fifty-five patients with one or more neurologist visits with epilepsy diagnoses (ICD-9 345.xx, 780.3, or 780.39), one or more procedures for vagus nerve stimulator implantation, one or more antiepileptic drugs (AEDs), and 6 or more months of continuous Medicaid enrollment pre- and post-VNS were selected. The pre-VNS period was 6 months. The post-VNS period extended from implantation to device removal, death, Medicaid disenrollment, or study end (up to 3 years). Incidence rate ratios (IRRs) and cost differences ($2009) were estimated. Mean age was 29.4 years. Hospitalizations decreased post-VNS compared with pre-VNS (adjusted IRR=0.59, P<0.001). Grand mal status events decreased post-VNS compared with pre-VNS (adjusted IRR=0.79, P<0.001). Average total health care costs were lower post-VNS than pre-VNS ($18,550 vs $19,945 quarterly, P<0.001). VNS is associated with decreased resource utilization and epilepsy-related clinical events and net cost savings after 1.5 years.

Ictal tachycardia: the head-heart connection.

Epileptic seizures can lead to changes in autonomic function affecting the sympathetic, parasympathetic, and enteric nervous systems. Changes in cardiac signals are potential biomarkers that may provide an extra-cerebral indicator of ictal onset in some patients. Heart rate can be measured easily when compared to other biomarkers that are commonly associated with seizures (e.g., long-term EEG), and therefore it has become an interesting parameter to explore for detecting seizures. Understanding the prevalence and magnitude of heart rate changes associated with seizures, as well as the timing of such changes relative to seizure onset, is fundamental to the development and use of cardiac based algorithms for seizure detection. We reviewed 34 articles that reported the prevalence of ictal tachycardia in patients with epilepsy. Scientific literature supports the occurrence of significant increases in heart rate associated with ictal events in a large proportion of patients with epilepsy (82%) using concurrent electroencephalogram (EEG) and electrocardiogram (ECG). The average percentage of seizures associated with significant heart rate changes was similar for generalized (64%) and partial onset seizures (71%). Intra-individual variability was noted in several articles, with the majority of studies reporting significant increase in heart rate during seizures originating from the temporal lobe. Accurate detection of seizures is likely to require an adjustable threshold given the variability in the magnitude of heart rate changes associated with seizures within and across patients.

Clinical outcomes, quality of life, and costs associated with implantation of vagus nerve stimulation therapy in pediatric patients with drug-resistant epilepsy.

BACKGROUND: VNS (Vagus Nerve Stimulation Therapy) is approved in the USA to treat refractory epilepsy as adjunctive to antiepileptic drugs (AEDs) in patients ≥12 years with complex partial seizures. AIMS: To evaluate clinical outcomes, quality-adjusted life years (QALY), and costs associated with VNS in pediatric patients with drug-resistant epilepsy in a real-world setting. METHODS: A retrospective analysis was conducted using Medicaid data (USA). Patients had ≥1 neurologist visits with epilepsy diagnosis (ICD-9 345.xx, 780.3x), ≥1 procedure claims for VNS implantation, ≥1 AEDs, ≥6-months of Pre- and Post-VNS continuous enrollment. Pre-VNS period was 6-months and Post-VNS period extended from implantation until device removal, death, Medicaid disenrollment, or study end (up to 3 years). Incidence rate ratios (IRR) and costs ($2010) were estimated. QALYs were estimated using number of seizure-related events. RESULTS: For patients 1-11 years old (N = 238), hospitalizations and emergency room visits were reduced Post-VNS vs. Pre-VNS (adjusted IRR = 0.73 [95% CI: 0.61-0.88] and 0.74 [95% CI: 0.65-0.83], respectively). Average total healthcare costs were lower Post-VNS vs. Pre-VNS ($18,437 vs. $18,839 quarterly [adjusted p = 0.052]). For patients 12-17 years old (N = 207), hospitalizations and status epilepticus events were reduced Post-VNS vs. Pre-VNS (adjusted IRR = 0.43 [95% CI: 0.34-0.54] and 0.25 [95% CI: 0.16-0.39], respectively). Average total healthcare costs were lower Post-VNS vs. Pre-VNS period ($14,546 vs. $19,695 quarterly [adjusted p = 0.002]). Lifetime QALY gain after VNS was 5.96 (patients 1-11 years) and 4.82 years (patients 12-17 years). CONCLUSIONS: VNS in pediatric patients is associated with decreased resource use and epilepsy-related events, cost savings, and QALY gain.