SAN FRANCISCO – A trio of psychiatrists urged colleagues at the annual meeting of the American Psychiatric Association to embrace the venerable antipsychotic clozapine in patients with treatment-resistant schizophrenia. They cautioned that clinicians may overestimate the true risk of the adverse effect of neutropenia in minority populations.
“Although clozapine is known to be a life-improving and even potentially lifesaving treatment, it remains underutilized in the U.S.,” said Claire C. Holderness, MD, a psychiatrist at Columbia University Irving Medical Center, New York. “It’s been estimated that between 35% and 40% of all patients with schizophrenia should be considered for a clozapine trial. However, only 4%-5% of patients with schizophrenia in the U.S. have ever received clozapine. This is in sharp contrast to other industrialized countries where approximately 20% or more of patients with schizophrenia are treated with clozapine.”
According to Dr. Holderness, research has shown that clozapine is even less likely to be prescribed to racial and ethnic minorities. A 2022 systematic review, for example, found that Black patients in the United States had between one-third and two-thirds the odds of being treated with the drug, compared with White patients after adjustment for potential confounders such as demographics. Hispanic/Latino patients were also less likely than Whites to be prescribed the drug.
As Dr. Holderness put it, the drug “been shown to be more effective in treatment-resistant schizophrenia than any other antipsychotic medication. Clozapine is also the most cost-effective treatment for treatment-resistant schizophrenia.” So why does this disparity exist despite clozapine’s benefits?
A 2018 systematic review of barriers to the drug’s usage identified several factors: “mandatory blood testing, fear of serious side-effects and lack of adherence by the patients, difficulty in identifying suitable patients, service fragmentation, and inadequate training in or exposure to using clozapine.” A 2016 British study, meanwhile, looked at the reasons that 45% of 316 patients stopped clozapine before 2 years. More than half of these patients stopped because of adverse effects.
Risk of neutropenia
At the APA presentation, psychiatrist Laura Clarke, MD, also of Columbia University Irving Medical Center, noted that there’s concern about one adverse effect in particular: neutropenia, or an abnormally low white blood cell count. Clozapine, she said, has a boxed warning about severe neutropenia that can lead to death.
However, she cautioned that white blood cell counts can be misleading. Some people in non-White ethnic groups have a condition known as benign ethnic neutropenia: their white blood cell counts are abnormal by the standards of people of European heritage, but they’re otherwise healthy. “These individuals do not show an increased risk of infections, and their response to infection is similar to those without them,” she said.
As many as 25%-50% of people of African ancestry may have benign ethnic neutropenia, making their blood levels appear abnormally low. Others with higher levels of the condition include certain Middle Eastern ethnicities and other ethnic groups with darker skin.
In these patents, “clinicians may avoid prescribing clozapine out of the mistaken concern that it can worsen neutropenia,” Dr. Clarke said. In fact, benign ethnic neutropenia “does not increase the risk of clozapine-induced severe neutropenia.”
Dr. Clarke highlighted drug use guidelines from the Clozapine Risk Evaluation and Mitigation Strategy, a Food and Drug Administration–mandated safety program designed to prevent severe neutropenia in patients taking clozapine. The guidelines note that the recommended absolute neutrophil count monitoring algorithm differs when patients are diagnosed with benign ethnic neutropenia.
Dr. T. Scott Stroup
T. Scott Stroup, MD, MPH, a psychiatrist at Columbia University, New York, urged his colleagues to consider clozapine early on in treatment-resistant schizophrenia. “Don’t go through three, four, or five antipsychotics. Even after trying two, I’d encourage people to [try clozapine].”
However, he acknowledged that “not everyone believes that. Many of my colleagues think that, before you try clozapine, you should have a trial of long-acting injectable medications to rule out pseudo–treatment resistance. I don’t totally agree with that, but I’ve more or less lost that battle,” he added.
In the big picture, Dr. Stroup said, clozapine “is good when other things aren’t working efficacy wise.”
Dr. Holderness and Dr. Clarke have no disclosures. Dr. Stroup discloses grants from the National Institutes of Health and royalties from APA Publishing and UpToDate.