Abstract
BACKGROUND
Many people with schizophrenia do not achieve a satisfactory treatment response with just antipsychotic drug treatment and various adjunct medications are used to promote additional response. The antiepileptic carbamazepine is one such drug.
OBJECTIVES
To examine whether carbamazepine or oxcarbazepine alone is an effective treatment for schizophrenia and schizoaffective psychoses and whether carbamazepine or oxcarbazepine augmentation of neuroleptic medication is an effective treatment for the same illnesses.
SEARCH METHODS
For the original version we searched The Cochrane Schizophrenia Group's Register of Trials (December 2001), The Cochrane Library (Issue 3, 2001), MEDLINE (1966-2001), EMBASE (1980-2001), Biological Abstracts (1980-2001), PsycLIT (1886-2001) and PSYNDEX (1974-2001). For the most recent update we searched the Cochrane Schizophrenia Group's Register of Trials in July 2012. We also inspected references of all identified studies for further trials and contacted relevant pharmaceutical companies and authors for additional data.
SELECTION CRITERIA
We included all randomised controlled trials (RCTs) comparing carbamazepine or compounds of the carbamazepine family with placebo or no intervention, whether as sole treatment or as an adjunct to antipsychotic medication for the treatment of schizophrenia and/or schizoaffective psychoses.
DATA COLLECTION AND ANALYSIS
We extracted data independently. For homogenous dichotomous data we calculated fixed-effect, risk ratio (RR), with 95% confidence intervals (CIs) on an intention-to-treat basis. For continuous data, we calculated mean differences (MD). We assessed the risk of bias for included studies and created a 'Summary of findings' table using GRADE.
MAIN RESULTS
The updated search did not reveal any further studies that met our inclusion criteria. The number of included studies therefore remains at 10 with the number of participants randomised still 283.One study comparing carbamazepine with placebo as the sole treatment for schizophrenia was abandoned early due to high relapse rate with 26 out of 31 participants relapsing by three months. No effect of carbamazepine was evident with no difference in relapse between the two groups (1 RCT n = 31, RR 1.07 CI 0.78 to 1.45). Another study compared carbamazepine with antipsychotics as the sole treatment for schizophrenia. No differences in terms of mental state were found when comparing 50% reduction in Brief Psychiatric Rating Scale (BPRS) scores (1 RCT n = 38, RR 1.23 CI 0.78 to 1.92). A favourable effect for carbamazepine was found when more people who received the antipsychotic (perphenazine) had parkinsonism (1 RCT n = 38, RR 0.03 CI 0.00 to 0.043). Eight studies compared adjunctive carbamazepine versus adjunctive placebo, we were able use GRADE for quality of evidence for these results. Adding carbamazepine to antipsychotic treatment was as acceptable as adding placebo with no difference between the numbers leaving the study early from each group (8 RCTs n = 182, RR 0.47 CI 0.16 to 1.35, very low quality evidence). Carbamazepine augmentation was superior compared with antipsychotics alone in terms of overall global improvement, but participant numbers were low (2 RCTs n = 38, RR 0.57 CI 0.37 to 0.88). There were no differences for the mental state outcome of 50% reduction in BPRS scores (6 RCTs n = 147, RR 0.86 CI 0.67 to 1.12, low quality evidence). Less people in the carbamazepine augmentation group had movement disorders than those taking haloperidol alone (1 RCT n = 20, RR 0.38 CI 0.14 to 1.02). No data were available for the effects of carbamazepine on subgroups of people with schizophrenia and aggressive behaviour, negative symptoms or EEG abnormalities or with schizoaffective disorder.
AUTHORS' CONCLUSIONS
Based on currently available randomised trial-derived evidence, carbamazepine cannot be recommended for routine clinical use for treatment or augmentation of antipsychotic treatment of schizophrenia. At present large, simple well-designed and reported trials are justified - especially if focusing on people with violent episodes and people with schizoaffective disorders or those with both schizophrenia and EEG abnormalities.
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