Estimating clozapine's cost to the nation.

Clozapine, an effective but expensive drug treatment for patients with severe, chronic schizophrenia who are unresponsive to conventional antipsychotics, is associated with a high risk of agranulocytosis, which is sometimes fatal. Weekly blood tests to detect evidence of this side effect are required. To estimate the number of potential candidates for this treatment and the national cost of administering the drug to this population, the authors used data from three recent patient surveys conducted in New York State. Depending on the criteria used to exclude unsuitable candidates, between 133,000 and 189,000 individuals will be eligible for treatment with clozapine nationally at a cost of $1.2 to $1.7 billion annually.