The study was terminated by the sponsor due to persistent delays in recruitment and data availability, including access to the healthcare resource utilization database, which made it difficult to generate meaningful outcomes.

This is a UK, multi-center, non-interventional study based on the use of health service administrative and medical records (paper-based and/or electronic, as applicable) along with the use of prospectively collected subject-reported outcomes on experience with use of VNS therapy using validated and bespoke self-completion questionnaires. Data for hospital resource utilisation will be extracted from the Hospital Episode Statistics (HES) database.

Failure to control seizures in subjects with treatment resistant epilepsy can have a significant burden on the healthcare system. Vagus Nerve Stimulation (VNS) is an adjunctive treatment for patients with drug resistant epilepsy and is reported to reduce the frequency of seizures in adults and children. However, real-world data on healthcare resource utilization by patients with treatment-resistant epilepsy and their clinical outcomes prior to and post VNS device implantation in the UK are limited. The current study aims to describe the resource utilization and clinical outcomes prior to and following the implantation of different VNS devices (Demipulse®/Aspire HC®, Aspire SR® and SenTiva®) in subjects with drug resistant epilepsy

Inclusion Criteria:

Living subjects who meet all of the following criteria will be considered for enrolment:

• Clinical diagnosis of drug resistant epilepsy
• Subjects who have had their first VNS device (Demipulse®/Aspire HC®, Aspire SR® and SenTiva®) implanted at least 18 months prior to their enrolment in the study data (with no change in generator, battery or lead).
• For SenTiva® and Aspire SR®, AutoStim was first activated within 1 month of implantation.
• For SenTiva®, scheduled dosing mode was activated within 1 month of implantation.
• Subjects must be able and willing to provide informed consent; subjects aged 7-12 years old and 13-15 years old will be provided with appropriate information and consent forms to explain the study in age appropriate language. These subjects will be asked to provide their assent to take part in the study, with consent provided by their parent/carer. Subjects under 7 years will be included in the study with consent from their parent/carer. For adult subjects (≥16 years) lacking the mental capacity to consent, advice about participation will be sought from an appropriate consultee, according to the Mental Capacity Act 2005.
• Adult and paediatric subjects (aged over 2.5 years at study enrolment) with available medical records for at least 12 months prior to VNS device implantation.

Exclusion Criteria:

• Subjects whose medical records are not available for review.
• Deceased subjects.

Male and female adult (aged ≥16 years at VNS implantation) and paediatric (aged 1-15 years at VNS implantation) subjects with epilepsy who have had a VNS device Demipulse®/Aspire HC®, Aspire SR® or SenTiva® implanted will be involved in this study.