Amisulpride vs olanzapine in schizophrenia. Preliminary results on short-term analysis

Atypical antipsychotics for people with both schizophrenia and depression

BACKGROUND

Many people (up to 50%) with schizophrenia also have co-morbid depression. It has been suggested that new atypical antipsychotic drugs are beneficial for people with the two diagnoses.

OBJECTIVES

To assess the effects of atypical antipsychotic drugs on people who have a diagnosis of both schizophrenia and depression.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia's Group Register (to March 2006). We supplemented this by citation searching and personal contact with authors and relevant pharmaceutical companies.

SELECTION CRITERIA

We included randomised clinical trials of atypical antipsychotic drugs used specifically for the treatment of people with a diagnosis of both schizophrenia and depression.

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 (NNT) on an intention-to-treat basis. For continuous data, we calculated weighted mean differences (WMD).

MAIN RESULTS

We found 878 citations but were only able to include three studies (five reports). One trial found no significant difference between quetiapine and haloperidol for the outcome of 'less than 50% reduction in PANSS score' (n=180, RR 0.91 CI 0.8 to 1.0). Those allocated sulpiride had significantly lower depression scores compared with people given chlorpromazine (1 RCT, n=36, WMD CPRS -0.70 CI -1.2 to -0.2). Again, however, in the quetiapine versus haloperidol comparison, the continuous scoring did not highlight differences (1 RCT, n=180, WMD PANSS depression change -0.57 CI -1.4 to 0.30). When clozapine was compared with any other antipsychotic drug plus an antidepressant or placebo, clozapine constantly scored better on Hamilton scores (1 RCT, n=29, WMD vs antipsychotic + mianserin -5.53 CI -8.23 to -2.8; 1 RCT, n=32, WMD vs antipsychotic + meclobemide -4.35 CI -6.7 to -2.03; 1 RCT, n=33, WMD vs antipsychotic + placebo -6.35 CI -8.6 to -4.1).

AUTHORS' CONCLUSIONS

There are too few data to guide patients, carers, clinicians or policy makers. Current practice has to be guided by evidence other than that derived from randomised trials and more trials in this important area are indicated.

Olanzapine for schizophrenia

BACKGROUND

Olanzapine is an atypical antipsychotic reported to be effective without producing disabling extrapyramidal adverse effects associated with older, typical antipsychotic drugs.

OBJECTIVES

To determine the clinical effects and safety of olanzapine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and schizophreniform psychoses.

SEARCH STRATEGY

We updated the first search [Biological Abstracts (1980-1999), The Cochrane Library (Issue 2, 1999), EMBASE (1980-1999), MEDLINE (1966-1999), PsycLIT (1974-1999) and The Cochrane Schizophrenia Group's Register (October 2000)] in October 2004 using the Cochrane Schizophrenia's Group's register of trials. We also searched references of all included studies for further trials, and contacted relevant pharmaceutical companies and authors.

SELECTION CRITERIA

We included all randomised clinical trials comparing olanzapine with placebo or any antipsychotic treatment for people with schizophrenia or schizophreniform psychoses.

DATA COLLECTION AND ANALYSIS

We independently extracted data and, for homogeneous dichotomous data, calculated the random effects relative risk (RR), the 95% confidence intervals (CI) and the number needed to treat (NNT) on an intention-to-treat basis. For continuous data we calculated weighted mean differences.

MAIN RESULTS

Fifty five trials are included (total n>10000 people with schizophrenia). Attrition from olanzapine versus placebo studies was >50% by six weeks, leaving interpretation of results problematic. Olanzapine appeared superior to placebo at six weeks for the outcome of 'no important clinical response' (any dose, 2 RCTs n=418, RR 0.88 CI 0.8 to 0.1, NNT 8 CI 5 to 27). Although dizziness and dry mouth were reported more frequently in the olanzapine-treated group, this did not reach statistical significance. The olanzapine group gained more weight. When compared with typical antipsychotic drugs, data from several small trials are incomplete. With high attrition in both groups (14 RCTs, n=3344, 38% attrition by six weeks, RR 0.81 CI 0.65 to 1.02) the assumptions included in all data are considerable. For the short term outcome of 'no important clinical response', olanzapine seems as effective as typical antipsychotics (4 RCTs, n=2778, RR 0.90 CI 0.76 to 1.06). People allocated olanzapine experienced fewer extrapyramidal adverse effects than those given typical antipsychotics. Weight change data for the short term are not statistically significant but results between three to 12 months suggest a clinically important average gain of four kilograms for people given olanzapine (4 RCTs, n=186, WMD 4.62, CI 0.6 to 8.64). Twenty three percent of people in trials of olanzapine and other atypical drugs left by eight weeks; 48% by three to12 months (11 RCTs, n=1847, RR 0.91 CI 0.82 to 1.00). There is little to choose between the atypicals, although olanzapine may cause fewer extrapyramidal adverse effects than other drugs in this category. Olanzapine produces more weight gain than other atypicals with some differences reaching conventional levels of statistical significance (1 RCT, n=980, RR gain at 2 years 1.73 CI 1.49 to 2.00, NNH 5 CI 4 to 7). There are very few data for people with first episode illness (1 RCT, duration 6 weeks, n=42). For people with treatment-resistant illness there were no clear differences between olanzapine and clozapine (4 RCTs, n=457).

AUTHORS' CONCLUSIONS

The large proportion of participants leaving studies early in these trials makes it difficult to draw firm conclusions on olanzapine's clinical effects. For people with schizophrenia it may offer antipsychotic efficacy with fewer extrapyramidal adverse effects than typical drugs, but more weight gain. There is a need for further large, long-term randomised trials with more comprehensive data.