Risperidone versus typical antipsychotic medication for schizophrenia

Risperidone is one of the 'new generation' antipsychotics. As well as its reputed tendency to cause fewer movement disorders than the older drugs such as chlorpromazine and haloperidol, it is claimed that risperidone may improve negative symptoms.

To evaluate the effects of risperidone for schizophrenia in comparison to 'conventional' neuroleptic drugs.

The original electronic searches of Biological Abstracts (1980-1997), Cochrane Schizophrenia Group's Register (1997), The Cochrane Library (1997, Issue 1), EMBASE (1980-1997), MEDLINE (1966-1997), PsycLIT (1974-1997), and SCISEARCH (1997) were updated with a new electronic search of the same databases in 2002. The search term used in the update was identical to that used in 1997. Any new studies or relevant references were added to the review. In addition, references of all identified studies were searched for further trial citations. Pharmaceutical companies and authors of trials were also contacted.

All randomised trials comparing risperidone to any 'conventional' neuroleptic treatment for people with schizophrenia or other similar serious mental illnesses.

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were also independently extracted. Where possible, sensitivity analyses on dose of risperidone, haloperidol and duration of illness were undertaken for the primary outcomes of clinical improvement, side effects (movement disorders) and acceptability of treatment. For homogeneous dichotomous data the Relative Risk (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat/harm (NNT/H) were calculated on an intention-to-treat basis.

In the short-term, risperidone was more likely to produce an improvement in the Positive and Negative Syndrome Scale (PANSS) when compared with haloperidol (n=2368, 9 RCTs, RR not 20% improved 0.72 CI 0.59 to 0.88 NNT 8). A similar, favourable outcome for risperidone was found in long-term studies (n=859, 2RCTs RR not 20% improved 0.51 CI 0.38 to 0.67 NNT 4;n=675 1RCT, RR not improved 40% 0.75 CI 0.66 to 0.84 NNT 5; n=675, 1 RCT, RR not 60% improved 0.90 CI 0.84 to 0.96, NNT 11). Risperidone was also more likely to reduce relapse at one year follow up, compared with haloperidol (n=367, 1 RCT, RR 0.64 CI 0.41 to 0.99, NNT 7). Less people allocated risperidone left studies before completion, both for short-term (n=3066, 16 RCTs, RR 0.76 CI 0.63 to 0.92, NNT 6) and long-term trials (n=1270, 4RCTs, RR 0.55 CI 0.42 to 0.73 NNT 4). For general movement disorders results favoured risperidone. People given risperidone had significantly fewer general movement disorders (including extrapyramidal side effects) than those receiving older typical antipsychotics (n=2702, 10 RCTs, RR 0.63 CI 0.56 to 0.71, NNT 3). Significantly fewer people given risperidone used antiparkinsonian drugs (n=2524, 11 RCTs, RR 0.66 CI 0.58 to 0.74, NNT 4). As regards body weight, however, four studies (n=1708) found people were more likely to gain weight if allocated risperidone compared to typical antipsychotics (RR 1.55 CI 1.25 to 1.93, NNH 3). Risperidone was no more or less likely than haloperidol to cause sexual problems such as erectile dysfunction (n=106, 2 RCTs, RR 1.55 CI 0.58 to 4.20). Finally, some results found risperidone was more likely to cause rhinitis than conventional antipsychotics (n=656, 3 RCTs, RR1.99 CI 1.24 to 3.19, NNH 3).

Risperidone may be more acceptable to those with schizophrenia than older antipsychotics and have marginal benefits in terms of limited clinical improvement. Its adverse effect profile may be better than haloperidol. With the addition of more studies to this review, the publication bias evident in previous versions is no longer a significant issue. Any marginal benefits this drug may have have to be balanced against its greater cost and increased tendency to cause side effects such as weight gain. Recent important longer term data favouring risperidone's effect on relapse needs to be replicated by researchers independently of the manufacturers of the drug.