New study compares effectiveness of clozapine with standard antipsychotics in adults with schizophrenia

In real-world settings, patients with schizophrenia whose symptoms do not respond to standard antipsychotic medications have better outcomes if they are switched to clozapine instead of another standard antipsychotic. They have fewer hospitalizations, stay on the new medication longer, and are less likely to need to use additional antipsychotics. These findings were published today in the American Journal of Psychiatry.

Schizophrenia is a serious mental disorder affecting up to one percent of the adult population. Antipsychotics are effective at relieving symptoms for most patients, but up to 30% do not respond well to standard treatments and are considered to have treatment-resistant schizophrenia. While trials have indicated that clozapine is effective for these cases, the effectiveness of clozapine in clinical practice has not previously been studied in depth.

Often when one traditional antipsychotic medication does not work, clinicians change to another traditional antipsychotic. Clozapine is often seen as a drug of last resort, although it is the only medication approved by the FDA for treatment-resistant schizophrenia.

The new study was conducted using national Medicaid data from 6,246 patients whose treatment patterns were consistent with treatment resistance. It is the largest study directly comparing the effectiveness of clozapine with standard antipsychotics in this population in routine practice settings.

The results are encouraging and timely because the FDA recently broadened access to clozapine. In the past access was limited, in part because of the risk of agranulocytosis, a condition that can make people susceptible to infections. A system has been in place for 25 years to successfully manage the risks of agranulocytosis, using regular monitoring of white blood cell levels. Leading clinicians thus believe the limits on use of clozapine have been overly restrictive. The new FDA rules still require regular blood monitoring, but allow prescribers to make decisions based on benefits and risks for individual patients rather than rigidly following universal standards.

"These results give clinicians important guidance for how to help an extremely vulnerable group of people," said T. Scott Stroup, MD, lead author of the study, and professor of psychiatry at Columbia University Medical Center and a research psychiatrist at New York State Psychiatric Institute. "By helping individuals with treatment-resistant schizophrenia get effective treatment sooner we can expect better outcomes."