Published in:
01-11-2002 | Original Research Article
Medication Treatment Patterns following Initiation on Olanzapine versus Risperidone
A Retrospective Analysis
Authors:
Dr Zhongyun Zhao, Sandra L. Tunis, Maureen J. Lage
Published in:
Clinical Drug Investigation
|
Issue 11/2002
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Abstract
Objective
To compare medication treatment patterns for patients with schizophrenia following initiation on olanzapine versus risperidone.
Methods
Retrospective analysis of a large, geographically diverse claims database of insured individuals identified 670 enrollees who: (1) were diagnosed with schizophrenia; (2) were initiated on olanzapine (n = 423) or risperidone (n = 247) monotherapy, and (3) had not been treated with olanzapine or risperidone during 1 year prior to initiation. Multivariate analyses were used to compare olanzapine and risperidone groups on treatment duration, the likelihood of receiving medication for at least 80% of days in the year post-initiation, the likelihood of receiving concomitant anti-Parkinsonian agents, and the likelihood of switching between medications of interest, by controlling for demographics, co-morbidities, and previous medication-use patterns.
Results
Compared with risperidone patients (mean dosage = 3.32 mg/day), patients treated with olanzapine (mean dosage = 10.45 mg/day) experienced a 29.4% increase in treatment duration (162 vs 213 days; p<0.0001), and a significantly higher probability of receiving medication for at least 80% of days in the year post-initiation (Odds Ratio [OR] = 2.057, p = 0.0002). Patients initiated on olanzapine versus risperidone were also found to be significantly less likely to use anti-Parkinsonian medications (OR = 0.639; p = 0.0284) and were significantly less likely to switch to risperidone than vice versa (OR = 0.275; p<0.0001).
Conclusions
Compared with risperidone, patients initiated on olanzapine experienced more favourable medication-use patterns. Olanzapine patients had a significantly longer duration of pharmacotherapy, a significantly higher likelihood of receiving medication treatment for at least 80% of days in the year post-initiation, a significantly lower likelihood of concomitant use of anti-Parkinsonian agents, and a significantly lower probability of switching between medications of interest than risperidone patients. Findings that patients initiated on olanzapine had more favourable medication treatment patterns have important clinical and economic implications. Interruptions in antipsychotic therapy have been previously linked to increases in psychotic symptoms and increased use of costly acute-care services.