Seven RCTs (n= 651) were included in the analysis. Study quality was not clearly reported. Two studies had adequate allocation concealment and six studies were double blind.
Acute treatment (n=187, three trials): Carbamazepine and lithium had similar anti-manic effects. Carbamazepine was found to cause fewer withdrawals from the trials (RR 0.55, 95% CI 0.34 to 0.91, p=0.02; NNH 6.61, 95% CI 0.03 to 0.28). The number of withdrawals due to adverse effects was not found to differ between carbamazepine and lithium, nor did the requirement for rescue medication.
Maintenance Treatment (n=464, four trials): In two trials carbamazepine was found to be equal in efficacy to lithium. The rate of relapse was found to be similar for both medications at one year, but beyond this time there was heterogeneity (I2=75%) between trials. Analysis of pooled results found no difference in withdrawal rates, but lithium was found to induce fewer withdrawals due to adverse effects (RR 1.91, 95% CI 1.02 to 3.57, p=0.04).