Mortality in Current and Former Users of Clozapine

Abstract

Clozapine (Clozaril®), a tricyclic dibenzodiazepine, causes fewer extrapyramidal side effects than do other antipsychotic drugs. Because it can induce agranulocytosis, however, clozapine is indicated only for schizophrenia that is not responsive to other therapies. To describe the drug's effects on mortality, we compared rates of various causes of death in 67,072 current and former clozapine users. We linked data from a national registry of clozapine recipients to the National Death Index and Social Security Administration Death Master Files, obtained death certificates, and calculated mortality rates for underlying causes of death using standardization to adjust for age, sex, and race. During 1991–1993, there were 396 deaths in 85,399 person-years for patients ages 10–54 years. Mortality was lower during current clozapine use than during periods of non-use. Mortality from suicide was decreased in current clozapine users by comparison with past users [rate ratio (RR) = 0.17; 95% confidence interval (CI) = 0.10–0.30]. During clozapine use, there were elevations in mortality rates for less common causes of death, including pulmonary embolism (RR for current exposure compared with past clozapine use = 5.2) and respiratory disorders (RR = 2.9). Clozapine appears to reduce mortality in severe schizophrenics, mostly by decreasing suicide rates.