Cost-effectiveness of clozapine monitoring after the first 6 months.
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 bench-mark 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 alternative 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.
Zhang
M
M
Veterans Affairs Health Services Research and Development Field Program, Veterans Affairs Medical Center, Little Rock, Ark, USA.
Owen
R R
RR
Pope
S K
SK
Smith
G R
GR
D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems / Q000191:economics*; D017668:Age of Onset; D000380:Agranulocytosis / Q000139:chemically induced / Q000453:epidemiology / Q000401:mortality; D003024:Clozapine / Q000009:adverse effects* / Q000191:economics / Q000627:therapeutic use*; D003362:Cost-Benefit Analysis; D016527:Drug Costs; D016903:Drug Monitoring / Q000191:economics*; D006801:Humans; D015994:Incidence; D007958:Leukocyte Count / Q000191:economics; D008875:Middle Aged; D019057:Quality-Adjusted Life Years; D012559:Schizophrenia / Q000097:blood / Q000188:drug therapy* / Q000191:economics
D003024:Clozapine