A randomized double-blind study of risperidone and olanzapine in the treatment of schizophrenia or schizoaffective disorder

Objective: The safety and efficacy of risperidone and olanzapine were compa red in a double-blind trial that used doses widely accepted in clinical pra ctice. Method: Subjects (N=377) who met DSM-IV criteria for schizophrenia or schiz oaffective disorder were randomly assigned to receive 2-6 mg/day of risperi done (mean modal dose=4.8 mg/day) or 5-20 mg/day of olanzapine (mean modal dose= 12.4 mg/day) for 8 weeks. Results: The two study groups were similar at baseline except that the olan zapine group was slightly younger than the risperidone group. Seventy-five percent of the participants completed the trial, with no between-treatment differences in the proportion of dropouts. Similar proportions of the rispe ridone and olanzapine groups reported extrapyramidal symptoms (24% and 20%, respectively). Severity of extrapyramidal symptoms was low in both groups, with no between-group differences. Total Positive and Negative Syndrome Sc ale scores and scores on the five Positive and Negative Syndrome Scale fact ors were improved in both groups at week 8 (subjects who completed the stud y) and endpoint jail subjects, including dropouts). There were overall betw een-treatment differences in efficacy. Comparison of individual factors fou nd no significant differences at endpoint; at week 8, however, improvements on Positive and Negative Syndrome Scale factors for positive symptoms and anxiety/depression were greater with risperidone than olanzapine. An increa se in body weight of greater than or equal to7% was seen in 27% of olanzapi ne participants and 12% of risperidone participants. Conclusions: Both treatments were well tolerated and efficacious. The frequ ency and severity of extrapyramidal symptoms were similar in the two treatm ent groups. Greater reductions in severity of positive and affective sympto ms were seen with risperidone than with olanzapine treatment among study co mpleters. There was no measure on which olanzapine was superior. Greater we ight gain was associated with olanzapine than with risperidone treatment.