Risperidone versus olanzapine for schizophrenia.Cochrane Database Syst Rev. 2005 Apr 18CD
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.
DATA COLLECTION AND ANALYSIS
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 <20% decrease PANSS by eight weeks' 1.01 CI 0.87 to 1.16). At least two thirds of people given risperidone or olanzapine experienced an adverse event (n=300, 2 RCTs, RR 1.16 CI 0.70 to 1.94). About 20% had anticholinergic symptoms (n=719, 3 RCTs, RR 1.12 CI 0.77 to 1.63) and 20% of both groups experienced insomnia (n=594, 3 RCTs, RR 1.33 CI 0.95 to 1.85) and approximately 33% sleepiness (n=719, 4 RCTs, 0.99 CI 0.79 to 1.23). One third of people given either drug experienced some extrapyramidal symptoms (n=893, 3 RCTs, RR 1.18 CI 0.75 to 1.88) but 25% of people using risperidone require medication to alleviate extrapyramidal adverse effects (n=419, 2 RCTs, RR 1.76 CI 1.25 to 2.48, NNH 8 CI 4 to 25). People allocated to risperidone were less likely to gain weight compared with those given olanzapine and the weight gain resulting from olanzapine can be considerable and of rapid onset (n=377, 1 RCT, RR gain more than 7% of their baseline weight 0.40 CI 0.23 to 0.70, NNT 8 CI 6 to 17). Risperidone may cause more sexual dysfunction than olanzapine (n=370, 2 RCTs, RR abnormal ejaculation 4.36 CI 1.38 to 13.76, NNH 20 CI 6 to 176; n=31, 1 RCT, RR impotence 2.43 CI 0.24 to 24.07). Within trials both drugs are associated with equal attrition (n=1217, 7 RCTs, RR leaving the study early 1.17 CI 0.92 to 1.49).