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. |
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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 |
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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). |
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Outcomes | Primary outcome: Seizure frequency (50% reduction of seizures) Secondary outcomes:
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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. |