Twenty-four randomised controlled trials (RCTs; n=6,321) were included in the review. Four reported direct comparisons between olanzapine and risperidone (n=853), seven compared olanzapine with haloperidol (n=2,915) and fifteen compared risperidone with haloperidol (n=2,618). One trial had three arms, evaluating olanzapine, risperidone and haloperidol. The duration of the studies ranged from 4 weeks to 12 months.
Short-term outcomes.
Direct comparisons showed a statistically significant (P<0.05) reduction in anticholinergic use with olanzapine compared with risperidone (OR 0.65, 95% CI 0.47, 0.90; 3 RCTs). This was supported by the indirect comparisons for all doses (OR 0.97, 95% CI 0.45, 1.50; 13 RCTs) and for clinically relevant doses (OR 0.88, 95% CI 0.41, 1.34; 5 RCTs).
There were no statistically significant differences in efficacy outcomes, drop-outs (due to adverse events, lack of efficacy or for any reason) or quality of life between olanzapine and risperidone when either direct or indirect comparisons were made.
Long-term outcomes.
Direct comparisons showed olanzapine to be superior to risperidone. Statistically significant differences (P<0.05) were observed in the following:
40% or more improvement in PANSS score (OR 1.63, 95% CI: 1.05, 2.53; 2 RCTs),
50% or more improvement in PANSS score (OR 19.1, 95% CI: 1.09, 3.37; 2 RCTs),
total change in PANSS score (WMD -5.35, 95% CI: -10.15, -0.55; 2 RCTs),
PANSS score negative change (WMD -1.39, 95% CI: -2.66, -0.13; 3 RCTs),
PANSS GPS score (WMD -2.88, 95% CI: -5.20, -0.57; 3 RCTs),
BPRS total change (WMD -3.23, 95% CI: -6.00, -0.46; 2 RCTs), QLS total change (WMD 5.23, 95% CI: 1.32, 9.15; 2 RCTs), QLS interpersonal relations change (WMD 2.53, 95% CI: 0.83, 4.23; 2 RCTs),
anticholinergic use (OR 0.45, 95% CI: 0.29, 0.70; 3 RCTs), and
drop-outs for any reason (OR 0.60, 95% CI 0.42, 0.88; 3 RCTs).
Only anticholinergic use was improved with olanzapine when indirect comparisons were made (3 RCTs for olanzapine and 2 RCTs for risperidone; OR 0.88, 95% CI: 0.41, 1.34).