Sixteen RCTs (n=8,222 at baseline) were included in the review. Sample sizes at baseline ranged from 85 to 1,493. Follow-up ranged from six weeks to 18 months.
The most consistent global outcome was that patients in olanzapine treatment groups continued treatment for a longer time or with better adherence than those treated with other second-generation antipsychotics.
Acute phase patients showed no differences between comparators in clinical global impression (two RCTs), overall symptoms of psychosis (five RCTs), depression or mania (one RCT). One study appeared to find a more stable response to treatment for risperidone versus olanzapine.
Results of trials in chronic patients were mixed. There was evidence for superior or equal effectiveness of olanzapine, quetiapine and risperidone from different trials. The most consistent differences in tolerability were increased weight gain and adverse impact on serum lipids in groups treated with olanzapine (eight RCTs found such an effect, one found equivalence with risperidone). A number of other differences in safety outcomes were reported by single trials.
No significant differences between second-generation antipsychotics were found in the use of concomitant medications