Time to discontinuation and self-discontinuation of olanzapine and risperidone in patients with schizophrenia in a naturalistic outpatient setting

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