Four RCTs (n=1,095) were included. Three studies compared oxcarbazepine to placebo. One study compared oxcarbazepine to carbamazepine. Studies were considered to be of poor to moderate quality. Three studies had adequate blinding and two studies had adequately described randomisation method, adequate allocation concealment or were free of selective reporting of outcomes. One study was free of other likely bias. Follow-up ranged from 10 to 112 days. There were some discrepancies in the relative risks reported in the text and forest plots (figures presented here were from the forest plots).
In adult patients, oxcarbazepine was associated with a greater chance of a 50% or greater reduction in seizure frequency at all doses: 600mg (RR 2.1, 95% CI 1.3 to 3.4, NNT=7; one trial), 1,200mg (RR 3.2, 95% CI 2.1 to 5.0, NNT=4; one trial) and 2,400mg (RR 3.9, 95% CI 2.6 to 6.0, NNT=3; one trial). The same applied to children who took doses of 30mg to 46mg per day (RR reported in the forest plots 1.9, 95% CI 1.3 to 2.8, NNT=5; one trial).
In adults, oxcarbazepine was associated with a greater chance of no seizures during follow-up at higher doses: 1,200mg (RR 17.6, 95% CI 2.4 to 130.4, NNT not reported; one trial) and 2,400mg (RR 25.4, 95% CI 6.3 to 103.1, NNT=5; two trials). There was no evidence of a difference in absence of seizures when the dose of 600mg of oxcarbazepine was compared to placebo in children on doses of 30mg to 46mg per day.
In adult patients, higher doses of oxcarbazepine were associated with significantly more adverse events than placebo: 1,200mg (RR 1.2, 95% CI 1.1 to 1.3, NNH=7; one trial) and 2,400mg (RR 1.3, 95% CI 1.2 to 1.4, NNH=5; two trials). There was no evidence of significant differences at the lower dose of 600mg of oxcarbazepine in adults or among children who took 30mg to 46mg per day.
Dropout rates from adverse events were significantly higher with higher doses of oxcarbazepine: 1,200mg (RR 4.2, 95% CI 2.5 to 7.0; one trial) and 2,400mg (RR 7.7, 95% CI 4.7 to 12.6; one trial). Dropouts were also significantly higher in children at a dose of 30mg to 46mg per day (RR 3.3, 95% CI 1.1 to 9.7; one trial). There was no evidence of a difference in dropout rates from adverse events with the lower dose (600mg) of oxcarbazepine in adults.
One trial found no evidence of significant differences in outcomes when oxcarbazepine was compared with carbamazepine.
There was no evidence of significant heterogeneity in the one subgroup analysis where two trials were combined.