Perceived Barriers and Facilitators of Clozapine Use: A National Survey of Veterans Affairs Prescribers

Clozapine is an atypical antipsychotic that the US Food and Drug Administration (FDA) approved for use in schizophrenia and suicidality associated with schizophrenia or schizoaffective disorder. Clozapine has been shown to be superior to other antipsychotic treatment for treatment resistant schizophrenia (TRS), which is defined as failure of 2 adequate trials of antipsychotic therapy.¹ Up to 30% of patients with schizophrenia are classified as treatment resistant.²

Clozapine is considered the drug of choice for patients with TRS in both the US Department of Veterans Affairs (VA) policies and other evidence-based guidelines and remains the only antipsychotic with FDA approval for TRS.^2-5 Patients treated with clozapine have fewer psychiatric hospitalizations, fewer suicide attempts, lower rates of nonadherence, and less antipsychotic polypharmacy compared with patients who are treated with other antipsychotic therapy.^6,7 A 2016 study by Gören and colleagues found that in addition to the clinical benefits, there is the potential for cost savings of $22,000 for each veteran switched to and treated with clozapine for 1 year even when accounting for the cost of monitoring and potential adverse event management.⁸ This translates to a total savings of > $80 million if current utilization were doubled and half of those patients continued treatment for 1 year within the Veterans Health Administration (VHA). However, despite evidence supporting use, < 10% of Medicaid-eligible patients and only 4% of patients with schizophrenia in the VHA are prescribed clozapine.^8,9

Clozapine is underutilized for a variety of reasons, including intensive monitoring requirements, potential for severe adverse drug reactions, and concern for patient adherence.⁸ Common adverse effects (AEs) can range from mild to severe and include weight gain, constipation, sedation, orthostatic hypotension, and excessive salivation. Clozapine also carries a boxed warning for agranulocytosis, seizures, myocarditis, other cardiovascular and respiratory AEs (including orthostatic hypotension), and increased mortality in elderly patients with dementia.

Severe agranulocytosis occurs in between 0.05% and 0.86% of patients, which led the FDA to implement a Risk Evaluation and Mitigation Strategy (REMS) program for clozapine prescribing in 2015. Prior to the REMS program, each of the 6 clozapine manufacturers were required to maintain a registry to monitor for agranulocytosis. Per the REMS program requirements, health care providers (HCPs), dispensing pharmacies, and patients must be enrolled in the program and provide an updated absolute neutrophil count (ANC) prior to prescribing or dispensing clozapine. This is potentially time consuming, particularly during the first 6 months of treatment when the ANC must be monitored weekly and prescriptions are restricted to a 7-day supply. With recent changes to the REMS program, pharmacists are no longer permitted to enroll patients in the REMS system. This adds to the administrative burden on HCPs and may decrease further the likelihood of prescribing clozapine due to lack of time for these tasks. Within the VHA, a separate entity, the VA National Clozapine Coordinating Center (NCCC), reduces the administrative burden on HCPs by monitoring laboratory values, controlling dispensing, and communicating data electronically to the FDA REMS program.¹⁰

Despite the various administrative and clinical barriers and facilitators to prescribing that exist, previous studies have found that certain organizational characteristics also may influence clozapine prescribing rates. Gören and colleagues found that utilization at VHA facilities ranged from < 5% to about 20% of patients with schizophrenia. In this study, facilities with higher utilization of clozapine were more likely to have integrated nonphysician psychiatric providers in clinics and to have clear organizational structure and processes for the treatment of severe mental illness, while facilities with lower utilization rates were less likely to have a point person for clozapine management.¹¹

Although many national efforts have been made to increase clozapine use in recent years, no study has examined HCP perception of barriers and facilitators of clozapine use in the VHA. The objective of this study is to identify barriers and facilitators of clozapine use within the VHA as perceived by HCPs so that these may be addressed to increase appropriate utilization of clozapine in veterans with TRS.