Risperidone versus olanzapine for schizophrenia

Antipsychotic medication is a mainstay of treatment for schizophrenia and risperidone and olanzapine are the most popular treatment choice of the new generation drugs. To determine the clinical effects, safety and cost effectiveness of risperidone compared with olanzapine for treating schizophrenia. We searched the Cochrane Schizophrenia Group's Register (June 2004) which is based on regular searches of, amongst others, BIOSIS, CENTRAL, CINAHL, EMBASE, MEDLINE and PsycINFO. References of all identified studies were inspected for further trials. We also contacted relevant pharmaceutical companies for additional information. We included all clinical randomised trials comparing risperidone with olanzapine for schizophrenia and schizophrenia-like psychoses. We extracted data independently. For homogenous dichotomous data we calculated random effects, relative risk (RR), 95% confidence intervals (CI) and, where appropriate, numbers needed to treat/harm (NNT/H) on an intention-to-treat basis. For continuous data, we calculated weighted mean differences (WMD). We found no difference for the outcome of unchanged or worse in the short term (n=548, 2 RCTs, RR 1.00 CI 0.88 to 1.15). One study, sponsored by the manufactures of olanzapine, favoured this drug for the outcome of relapse/rehospitalisation by 12 months (n=279, RR 2.16 CI 1.31 to 3.54, NNT 7 CI 4 to 25). Most mental state data showed the two drugs to as effective as each other (n=552, 2 RCTs, RR 'no