Skip to main content
. 2022 Jul 14;2022(7):CD002896. doi: 10.1002/14651858.CD002896.pub3

Handforth 1998.

Study characteristics
Methods Randomised, prospective, double‐blind, active‐control study
Pre‐randomisation baseline period: 12 to 16 weeks
Duration of treatment: 16 weeks. This period included 2, 12, and 16‐week time points.
Participants A multicentre trial (USA)
198 people randomised
High stimulation group: 95 participants; mean age 32.1 years; 51.6% male and 48.4% female; mean seizures/day 1.59; mean duration of epilepsy 22.1 years
Low stimulation group: 103 participants; mean age 34.2 years; 42.7% male and 57.3% female; mean seizures/day 0.97; mean duration of epilepsy 23.7 years
Interventions Comparison of high (on/off cycles of 30 seconds every 5 minutes, each 'on' period consisting of 500 µs duration pulses at 30 Hz frequency) and low stimulation (on/off cycles of 30 seconds every 3 hours, each 'on' cycle of 130 µs duration pulse at 1 Hz frequency) in treatment of refractory focal seizures
All participants had an identical implantation of the vagus nerve stimulation device (NeuroCybernetic Prosthesis, Cyberonics).
Outcomes Primary outcome:
Seizure frequency (50% reduction of seizures)
Secondary outcomes:

  1. Treatment withdrawal

  2. Adverse events

  3. Cognitive impact

  4. Quality of life (QOL) impact
Notes Supported by a grant from Cyberonics, Inc., Webster, TX
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Randomisation schedule was generated by a statistical consultant before study initiation.
Allocation concealment (selection bias) Low risk Telephone communication to obtain randomised treatment assignment
Blinding of participants and personnel (performance bias)
All outcomes Low risk Study personnel and participants were blinded. Identical implants used
Blinding of outcome assessment (detection bias)
All outcomes Low risk The study data were analysed by a blinded interviewer. Identical implants used
Incomplete outcome data (attrition bias)
All outcomes Low risk 4 participants withdrew, but the reasons for exclusion were reported.
Selective reporting (reporting bias) Unclear risk All outcomes stated in the methods section of the paper were reported in the results. There was no protocol available to check a priori outcomes.
Other bias Unclear risk All studies were sponsored by Cyberonics, the manufacturer of the device.