Background: Although efficacy of antipsychotic medications is well documented, their effectiveness in real-world practice is less robust. We examined the effectiveness of olanzapine and risperidone in schizophrenia in a naturalistic setting.
Methods: We used an electronic medical records database at a Veterans Affairs Medical Center to conduct a retrospective study of all new outpatient medication trials of olanzapine (n = 221) and risperidone (n = 274) over a 2-year period beginning January 1999 in patients diagnosed with schizophrenia or schizoaffective disorder. We defined medication discontinuation as a switch between the 2 agents (most switches) or self-discontinuation when a patient is without medication supply for longer than 1 month.
Results: Sample mean age (+/-SD) was 48.4 (+/-11.6) years; 91% were men. Discontinuation rates were high (73%), trending lower in olanzapine (70%) than risperidone (76%) (P = 0.12). Median time to discontinuation was 120 days (95% confidence interval [CI], 105-135), longer for olanzapine (150 days; 95% CI, 120-180) than risperidone (90 days; 95% CI, 71-109) (P = 0.04). Self-discontinuation was high (48%), with no significant difference between olanzapine (50%) and risperidone (46%). Switching rate was 25% and more likely to occur in risperidone (30%) than olanzapine (20%) (odds ratio, 1.72; 95% CI, 1.13-2.61).
Conclusions: Effectiveness of antipsychotic medications in schizophrenia may be hampered by high rates of medication self-discontinuation in outpatient practice settings. Time to discontinuation suggests that olanzapine may be more effective than risperidone. Strategies to address causes of poor adherence should be incorporated in medication algorithms to optimize their effectiveness.