Aripiprazole versus other atypical antipsychotics for schizophrenia

Background In many countries of the industrialised world second generation ( atypical) antipsychotics have become first line drug treatments for people with schizophrenia. The question as to whether, and if so how much, the effects of the various second generation antipsychotics differ is a matter of debate. In this review we examine how the efficacy and tolerability of aripiprazole differs from that of other second generation antipsychotics. Objectives To evaluate the effects of aripiprazole compared with other atypical antipsychotics for people with schizophrenia and schizophrenia-like psychoses. Search strategy We searched the Cochrane Schizophrenia Group Trials Register ( March 2007) which is based on regular searches of BIOSIS, CENTRAL, CINAHL, EMBASE, MEDLINE and PsycINFO. Selection criteria We included all randomised trials comparing oral aripiprazole with oral forms of amisulpride, clozapine, olanzapine, quetiapine, risperidone, sertindole, ziprasidone or zotepine in people with schizophrenia or schizophrenia-like psychoses. Data collection and analysis We extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated weighted mean differences ( MD) again based on a random-effects model. Main results The review currently includes four trials with 1404 participants on two out of eight possible comparisons - aripiprazole versus olanzapine and aripiprazole versus risperidone. The overall number of participants leaving the studies early was considerable (38.5%), limiting the validity of the findings, but with no significant differences between groups. Aripiprazole was less efficacious than olanzapine in terms of the general mental state (PANSS total score: n=794, 2 RCTs, MD 4.96 CI 1.85 to 8.06), but it was associated with fewer side-effects such as cholesterol increase, weight gain, sedation and prolactin associated side-effects. Compared with risperidone there was no difference in efficacy ( PANSS total score: n=372, 2 RCTs, MD 1.50 CI -2.96 to 5.96). Dystonia, QTc abnormalities, prolactin and cholesterol increase were less frequent in the aripiprazole group, while tremor was more frequent in the aripiprazole group compared with those allocated risperidone. Authors' conclusions Aripiprazole may be somewhat less effective than olanzapine, but more tolerable in terms of metabolic effects and sedation. There is no evidence for a difference in efficacy compared to risperidone, but for better tolerability in terms of dystonias, cholesterol prolactin increase and QTc prolongation. Randomised evidence comparing aripiprazole with other second generation antipsychotic drugs is currently not available.