Betts 2000.
| Methods | Randomised double‐blind placebo‐controlled parallel trial 3 treatment arms: 1 PCB and 2 LEV Randomisation concealment: allocated sequentially sealed, numbered packages containing either LEV or PCB. Random list generation: computer‐generated random permuted blocks (size 3) Blinding: identical tablets and packages. Investigators were described as blinded to treatment assignment. If treatment code was broken, the patient had to be removed from the trial Baseline = 4 weeks. No titration period. Treatment period = 24 weeks |
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| Participants | All adults. Multicentre across Europe. Total randomised 119 adults 39 adults to PCB 42 adults to LEV 2000‐mg 38 adults to LEV 4000 mg 61% male Age range 16 to 67 years Other AEDs 1 to 3 ≥ 4 seizures in 6 months before study entry Mean duration of epilepsy (± SD) (years): LEV 2000 mg = 21.1 ± 14.4; LEV 4000 mg = 24.6 ± 15.6; PCB = 26.0 ± 13.2 Median of baseline seizure frequency per week: LEV 2000 mg = 1.21; LEV 4000 mg = 1.34; PCB = 1.24 |
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| Interventions | LEV 2000 mg/day LEV 4000 mg/day PCB add‐on |
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| Outcomes | Treatment withdrawal Adverse effects QoL and cognitive effects |
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| Notes | Baseline seizure frequency data were derived from N = 34, N = 36, and N = 36 patients in the LEV 2000 mg, LEV 4000 mg groups, and PCB, respectively In the text for the trial, the number of participants in the inferential ITT population was reported as N = 27, N = 28, and N = 31, in the LEV 2000 mg, LEV 4000 mg, and PCB groups, respectively. In a graph for the trial, the number of participants in the inferential ITT population was reported as N = 26 N = 28, and N = 25, in the LEV 2000 mg, LEV 4000 mg, and PCB groups, respectively All participants had drug‐resistant epilepsy and some had generalised‐onset and unclassified seizures QoL was assessed using the ESI‐55 for 30 to 31 participants in LEV 2000 mg, 26 to 28 participants in LEV 4000 mg, and 28 participants in PCB |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A ‐ Adequate |
| Allocation concealment (selection bias) | Low risk | A ‐ Adequate |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | A ‐ Adequate |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | A ‐ Adequate |
| Incomplete outcome data (attrition bias) All outcomes | High risk | C ‐ Inadequate (for outcome of ≥ 50% reduction in seizure frequency) |
| Selective reporting (reporting bias) | High risk | C ‐ Inadequate (for outcome of ≥ 50% reduction in seizure frequency) |