Clozapine revisited: Impact of clozapine vs olanzapine on health care use by schizophrenia patients on Medicaid.

Background: Our purpose was to evaluate health care use and cost patterns for clozapine compared with olanzapine in the treatment of schizophrenia.

Methods: Health care outcomes were measured over a 1-year posttreatment period for episodes of antipsychotic therapy initiated between 1997 and 2002. Four episode categories were defined: restart after lapse in therapy, switch after break, switch without break, and augmentation. We estimated the impact of clozapine or olanzapine using mixed model regression for costs by type of service and days of uninterrupted drug therapy. Time to admission in an acute hospital, psychiatric hospital, or longterm care facility, and time to suicide attempt were compared using Cox proportional hazards models.

Results: Clozapine increased duration of therapy and decreased risk of psychiatric hospitalization or suicide attempts compared to olanzapine. However, increased drug costs and use of community mental health centers (CMHC) for complete blood count (CBC) monitoring overwhelmed any offsetting savings.

Conclusions: Clozapine is more expensive than olanzapine over the first year of treatment, primarily due to frequent CMHC visits required for CBC monitoring. However, fewer psychiatric hospitalizations, reduced suicide attempts, and longer duration of treatment should generate more benefits over time, which could eventually outweigh clozapine's higher first-year costs.