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October 1996

Cost-effectiveness of Clozapine Monitoring After the First 6 Months

Author Affiliations

From the Veterans Affairs Health Services Research and Development Field Program, Veterans Affairs Medical Center, Little Rock, Ark (Drs Zhang, Owen, and Smith); and Centers for Mental Healthcare Research (Drs Zhang, Owen, and Smith) and Center for Outcomes Research and Effectiveness (Drs Zhang, Owen, and Smith and Ms Pope), Department of Psychiatry, University of Arkansas for Medical Sciences, Little Rock.

Arch Gen Psychiatry. 1996;53(10):954-958. doi:10.1001/archpsyc.1996.01830100104013

Background:  Clozapine is effective in treating patients with schizophrenia who do not respond to conventional neuroleptic drugs. The drug is unique in that it is available only with a US Food and Drug Administration-mandated system for weekly monitoring of patients' white blood cell counts. No study has been conducted to evaluate the cost-effectiveness of this mandatory monitoring system.

Methods:  A benchmark case was established by utilizing cumulative incidence rates of agranulocytosis from a recent study with a large sample of clozapine-treated patients. We assumed a 20% mortality among patients with agranulocytosis, $30.61 in monitoring costs each week, and 14.4 years of remaining life expectancy after detection of agranulocytosis. Based on these benchmark assumptions, cost-effectiveness ratios in dollars per quality-adjusted life-year were calculated for the first, second, and third 6-month periods during which a patient was receiving clozapine. Sensitivity analyses were performed with more conservative assumptions in 5 alternative scenarios.

Results:  In the benchmark case, costs per quality-adjusted life-year gained were $61 694, $925 418, and $420 644 for the first, second, and third 6-month periods of clozapine treatment, respectively. In the aIternative scenarios, these costs ranged from $7923 to $46 056 for the first 6-month period and from $54 025 to $690 850 for the second and third 6-month periods.

Conclusions:  While the costs of monitoring patients with schizophrenia in the first 6-month period of clozapine treatment seem to be justifiable, monitoring thereafter may not be cost-effective because of the very low incidence of agranulocytosis in the later periods.

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