Clozapine prescribing barriers in the management of treatment-resistant schizophrenia: A systematic review

Sex differences in clozapine prescription: Results from an Italian 30-year health records registry

BACKGROUND

Clozapine is the only approved medication for treatment-resistant schizophrenia which is equally prevalent on male and female patients. However, studies showed that clozapine is less frequently prescribed to women compared to men.

AIMS

This study aims to investigate the role of sex in clozapine prescription, taking into account potential sociodemographic and clinical confounding factors.

METHODS

Patients aged 18-65, with a diagnosis of schizophrenia spectrum disorders were selected from the 46,222 individuals who had access to outpatient psychiatric services of Ferrara, Italy, from 1991 to 2021. Sociodemographic and clinical information including clozapine prescription timing and dosage were analyzed.

RESULTS

Among 3901 patients with a schizophrenia spectrum disorders, those who had been prescribed clozapine (189, 4.8%) were significantly more likely to be male (57%), younger at admission to care (30 vs 39.7 years old) and with a schizophrenia diagnosis (77% vs. 49%) compared to those without clozapine prescription. Within patients with a diagnosis of schizophrenia (n = 145), women (n = 60, 41%), compared to men, experienced twice the delay to be prescribed clozapine, both from the prescription of the first antipsychotic to clozapine (mean 1265.7 vs 746.6 days in men, p = 0.03) and from the prescription of the third antipsychotic to clozapine (mean 1214.5 vs 725.8 days in men, p = 0.03). Also, within those diagnosed with schizophrenia, women with a diagnosis of schizophrenia were less likely than men to be prescribed clozapine after the first and third antipsychotic considering both crude (HR = 0.66, p = 0.07; HR = 0.53, p = 0.025) and adjusted hazard ratios (HR = 0.65, p = 0.07; HR = 0.51, p = 0.021).

CONCLUSIONS

This study showed disparities based on sex in both the use and timing of clozapine, which disadvantages women diagnosed with schizophrenia. Further interventions are needed to increase awareness of possible sex-based barriers to clozapine use in clinical practice, measurement of sources of gender specific bias, and quality improvement initiatives to continuously address challenges in providing adequate treatment to this vulnerable population.

Elimination of the clozapine risk evaluation and mitigation strategy (REMS) - Improving access to care for those with treatment-refractory schizophrenia

A variety of pharmacological treatment options exist for schizophrenia, although as many as 20 % to 40 % of individuals with schizophrenia experience treatment-refractory symptoms. Typically defined by non-response to at least two sequential, adequate trials of antipsychotics, treatment-refractory schizophrenia represents a significant clinical challenge. Currently, clozapine (Clozaril) is the only evidence-based treatment strategy available for treatment-refractory schizophrenia. Nonetheless, clozapine has long remained underutilized due to administrative barriers such as the Food and Drug Administration (FDA) Risk Evaluation and Mitigation Strategy (REMS) program, a historical requirement for clozapine prescribing. The FDA has eliminated the clozapine REMS program effective February 2025. This editorial provides an update on clozapine and recognizes that elimination of the clozapine REMS program will reduce barriers to clozapine prescribing.

What is the current scope of research assessing patients' and clinicians' perspectives on clozapine treatment? A comprehensive scoping review

OBJECTIVES

Clozapine is continuously underused. The existing systematic reviews addressing barriers to clozapine prescribing primarily focus on clinical staff's attitudes and perceived barriers to prescribing. However, a preliminary literature search revealed additional literature on the subject not previously included in systematic reviews, including literature on patient perspectives. A scoping review is warranted to map the scope of primary studies on patients' and/or clinicians' perspectives on clozapine treatment and to identify gaps in research.

DESIGN

A scoping review was designed and reported in accordance with established guidelines for scoping reviews.

DATA SOURCES

The electronic databases Cochrane Library, CINAHL, Web of Science, PsycINFO, MEDLINE, EMBASE, Google Scholar and two grey literature databases were searched. Furthermore, citation tracking of selected studies was undertaken.

ELIGIBILITY CRITERIA

We included primary, empirical studies reporting clinicians' and/or patients' perspectives on clozapine treatment. No limitation was set for the year of publication or type of primary study.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently screened for studies, extracted the data and coded the content. Findings were summarised visually and narratively.

RESULTS

146 studies were included. Most studies reported on patients' or clinicians' perspectives on active clozapine treatment or on clinicians' perspectives on barriers to clozapine initiation in general. Three gaps in research were identified: (1) clozapine-eligible, yet clozapine-naïve, patients' attitudes towards clozapine commencement, (2) clinicians' reasons for clozapine withholding and perceived facilitators of clozapine treatment in specific patient-cases and (3) patient and clinician perspectives on clozapine discontinuation, continuation and rechallenge in specific patient cases.

CONCLUSIONS

Research on clozapine perspectives tends to repeat itself. Future studies addressing the identified gaps in evidence could provide the insights needed to optimise clozapine utilisation.

Pharmacovigilance in Action: Utilizing VigiBase Data to Improve Clozapine Safety

Purpose

Clozapine is an antipsychotic which was approved in 1989 for treatment-resistant schizophrenia in the United States (US). There were few randomized trials before its approval and potentially lethal clozapine adverse drug reactions (ADRs), such as agranulocytosis and myocarditis were identified by pharmacovigilance. VigiBase, the WHO global database, is a cornerstone of international pharmacovigilance efforts for ADR identification during post-marketing surveillance. This systematic review of the literature explores additional contributions to the knowledge of clozapine ADRs from recent VigiBase studies.

Methods

Using the terms "clozapine AND VigiBase" we conducted an article search in PubMed on September 5, 2024. Of the 29 articles, 11 were excluded and 18 described in the Results section.

Results

All clozapine ADRs were described in two VigiBase studies. One on pregnancy indicated no increased risk with clozapine compared with other antipsychotics; the other reported 191,557 clozapine ADRs, including 22,956 fatal outcomes through January 15, 2023, and paid attention to the reporting style of the top 4 reporting countries (the US, the United Kingdom, Canada and Australia). Infections were described in three VigiBase studies where clozapine treatment was associated with infections, respiratory aspiration, and pneumonia. Rapid titration can lead to localized clozapine-induced inflammations including myocarditis, pericarditis or pancreatitis, or generalized inflammations such as drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Clozapine-induced inflammation was described in four VigiBase studies, two focused on all ages (myocarditis and DRESS) and two on youth (myocarditis and another on pericarditis and pancreatitis). Other specific ADRs were described in nine VigiBase studies (hematological malignancies, rhabdomyolysis, sialorrhea, seizures, diabetes mellitus, drug-induced parkinsonism, withdrawal symptoms, and suicidal behaviors).

Conclusion

The spectrum of respiratory aspiration - aspiration pneumonia - pneumonia and other infections are significant causes of fatal outcomes in clozapine-treated patients. Clozapine had anti-suicidal effects versus other antipsychotics across all VigiBase labels of suicidal behavior.

Medical, Psychiatric, and Sociodemographic Predictors of Clozapine Initiation at an Academic Medical Center

Background and Hypothesis

Clozapine is an effective yet underutilized treatment for treatment-resistant schizophrenia spectrum disorders. This study aimed to identify factors affecting clozapine prescribing patterns among patients with treatment-resistant schizophrenia and schizoaffective disorder at an academic medical center.

Study Design

This retrospective combined cohort and case-control study examined demographic, socioeconomic, medical and psychiatric characteristics to determine predictors of clozapine initiation. Eligible patients had a diagnosis of schizophrenia or schizoaffective disorder with at least two prior antipsychotic trials and were admitted to a University of Utah inpatient psychiatric facility (1/2014-3/2021). Patients who did and did not receive clozapine during the index hospitalization were compared in cohort and case-control study arms.

Study Results

Twelve percent (59/477) of the cohort received clozapine during the index admission. Among the cohort (n = 477), Black patients were twice as likely to receive clozapine than White and Hispanic patients (OR 2.18, 95% CI 1.20-3.97, p = 0.008). In the case-control analysis, patients with a greater number of previous psychiatric admissions (OR 1.14, p = 0.079) and antipsychotic trials (OR 1.40, p = 0.038) had greater odds of receiving clozapine. Homelessness was identified as a predictor against clozapine use (OR 2.77, p = 0.014).

Conclusions

This is the first study to identify homelessness as a predictor against clozapine use, which raises important clinical and ethical considerations. Our findings also add to the literature on clozapine prescribing discrepancies among ethnic-minority patients. Overall, clozapine remains underutilized as the gold-standard treatment for treatment-resistant schizophrenia-spectrum disorders, reinforcing a need to improve evidence-based prescribing.

Can lithium be used in the setting of clozapine commencement in patients with COVID-19 associated neutropenia: A case report

COVID-19 infection may increase the likelihood of neutropenia in patients already on clozapine. In clozapine treated patients experiencing COVID-19 associated neutropenia, adjunct therapy with lithium can be considered.

Non-prescribing of clozapine for outpatients with schizophrenia in real-world settings: The clinicians' perspectives

Clozapine is the gold standard for treating treatment-resistant schizophrenia although continuously underutilized. Previous surveys of clinicians have found that some of the most frequently cited barriers to clozapine prescribing are related to the blood-monitoring requirements. However, these surveys tend to explore general perspectives and may not reflect the true impact of different barriers in real-world outpatient settings. This study aimed to explore this issue. First, by surveying the clinicians responsible for the treatment of 39 clozapine-eligible, yet clozapine-naive, outpatients with schizophrenia. Then, based on the survey results, explanatory interviews with the participating psychiatrists were conducted and analyzed thematically. The most frequently cited reason for non-prescribing of clozapine was the expected non-compliance with blood-monitoring requirements; however, overall stability and/or severe mental illness was chosen as the most important reason in most patient-cases. The qualitative analysis highlighted the combined impact of standard clinical practice, personal experiences, and organizational constraints on clozapine utility.

Comprehensive dissection of prevalence rates, sex differences, and blood level-dependencies of clozapine-associated adverse drug reactions

Clozapine is often underused due to concerns about adverse drug reactions (ADRs) but studies into their prevalences are inconclusive. We therefore comprehensively examined prevalences of clozapine-associated ADRs in individuals with schizophrenia and demographic and clinical factors associated with their occurrence. Data from a multi-center study (n = 698 participants) were collected. The mean number of ADRs during clozapine treatment was 4.8, with 2.4 % of participants reporting no ADRs. The most common ADRs were hypersalivation (74.6 %), weight gain (69.3 %), and increased sleep necessity (65.9 %), all of which were more common in younger participants. Participants with lower BMI prior to treatment were more likely to experience significant weight gain (>10 %). Constipation occurred more frequently with higher clozapine blood levels and doses. There were no differences in ADR prevalence rates between participants receiving clozapine monotherapy and polytherapy. These findings emphasize the high prevalence of clozapine-associated ADRs and highlight several demographic and clinical factors contributing to their occurrence. By understanding these factors, clinicians can better anticipate and manage clozapine-associated ADRs, leading to improved treatment outcomes and patient well-being.

Analytical Performance Evaluation of Three Point-of-Care CBC Analyzers for Management of Clozapine Therapy in Ambulatory Psychiatry Clinics

BACKGROUND

Clozapine is a first-line therapy and the only FDA-approved drug for patients with treatment-resistant schizophrenia (TRS). However, frequent measurement of absolute neutrophil count (ANC) is required to monitor for potential adverse severe neutropenia from clozapine therapy. We evaluated 3 point-of-care (POC) instruments that perform the complete blood count (CBC) with differential to assess their analytical performance and potential to meet the clinical need for clozapine therapy management.

METHODS

A CBC with differential was performed on 104 residual whole blood specimens using 3 CBC analyzers (Sight OLO, PixCell HemoScreen, and Sysmex pocH-100i) to assess analytical precision, linearity, and accuracy vs the ADVIA 2120i and manual differential reference methods. Clinical concordance of ANC between POC devices and manual differential at medical decision points for mild, moderate, or severe neutropenia, and the threshold for clozapine therapy discontinuation (1.0 × 109/L) were determined.

RESULTS

For CBC parameters, a CV ≤ 6.4% was observed on the OLO, CV ≤ 6.2% for the HemoScreen, and CV ≤ 5.1% with the pocH-100i. Each device accurately identified ANC with the greatest mean bias ±0.42 × 109/L using the pocH-100i vs manual differential. For results near the medical decision points (ANC <1.5 × 109/L), clinical concordance of ANC results was 55.6% for the OLO, 89.5% for the HemoScreen, and 82.4% for the pocH-100i.

CONCLUSIONS

The HemoScreen device demonstrated the best clinical concordance in ANC values at medical decision thresholds for clozapine therapy management.

Examining racial disparity in psychotic disorders related ambulatory care visits: an observational study using national ambulatory medical care survey 2010-2015

BACKGROUND

One of the most consistent research findings related to race and mental health diseases is the disproportionately high rate of psychotic disorder diagnoses among people of color, specifically people of African descent. It is important to examine if a similar pattern exists among specific psychotic disorders. We aimed to examine the racial/ethnic differences in ambulatory care visits diagnosed with schizophrenia-spectrum disorders (SSDs).

METHODS

We analyzed data from the National Ambulatory Medical Care Survey (NAMCS) 2010-2015. The study sample included physician office-based visits by individuals diagnosed with SSDs, including schizophrenia, schizoaffective, and unspecified psychotic disorder (n = 1155). We used descriptive and bivariate analysis by race/ethnicity and three multinomial logistic regression models to test the association between the SSDs and race/ethnicity, adjusting for age, gender, insurance, disposition, medication Rx, and co-morbidity, considering the design and weight.

RESULT

Of the 1155 visits for SSDs, 44.8% had schizophrenia, 37.4% had schizoaffective disorder diagnosis, and 19.0% had unspecified psychosis disorder. We found significant racial disparities in the diagnosis of SSDs. Black patients were overrepresented in all three categories: schizophrenia (24%), schizoaffective disorder (17%), and unspecified psychosis disorder (26%). Also, a notable percentage of Black patients (20%) were referred to another physician in cases of schizophrenia compared to other ethnoracial groups (p < 0.0001). Moreover, we found a significant disparity in insurance coverage for schizoaffective disorder, with a higher percentage of Black patients (48%) having Medicaid insurance compared to patients from other ethnoracial groups (p < 0.0001). Black patients had nearly twice the odds of receiving a diagnosis of schizophrenia compared to White patients [AOR = 1.94; 95% CI: 1.28-2.95; P = 0.001]. However, they had significantly lower odds of being diagnosed with schizoaffective disorder [AOR = 0.42, 95% CI: 0.26-0.68; P = 0.003]. Race/ethnicity was not associated with receiving an unspecified psychosis disorder.

CONCLUSIONS

Our results show that SSDs, more specifically schizophrenia, continue to burden the mental health of Black individuals. Validation of our findings requires rigorous research at the population level that reveals the epidemiological difference of SSDs diagnoses in different race/ethnicity groups. Also, advancing our understanding of the nature of disparity in SSDs diagnoses among the Black population requires disentangling etiologic and systemic factors in play. This could include psychological stress, the pathway to care, services use, provider diagnostic practice, and experiencing discrimination and institutional and structural racism.

A Case Study Demonstrating Applications of ChatGPT in the Clinical Management of Treatment-Resistant Schizophrenia

Chat Generative Pre-trained Transformer, also known as ChatGPT, is a new artificial intelligence (AI) program that responds to user inquiry with discourse resembling human language. The range of ChatGPT capabilities caught the interest of the medical world after it demonstrated its ability to pass medical boards examinations. In this case report, we present the clinical treatment of a 22-year-old male diagnosed with treatment-resistant schizophrenia (TRS) and compare the medical management suggested by ChatGPT to current standards of care in order to assess the program's ability to identify the disorder, evaluate potential medical and psychiatric work-up, and develop a treatment plan addressing the distinct nuances of our patient. In our inquiry with ChatGPT, we found that it can accurately identify our patient as having TRS and order appropriate tests to methodically rule out alternative causes of acute psychosis. Furthermore, the AI program suggests pharmacologic treatment options including clozapine with adjuvant medications, and nonpharmacologic treatment options including electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), and psychotherapy which align with current standards of care. Lastly, ChatGPT provides a comprehensive list of side effects associated with antipsychotics and mood stabilizers used to treat TRS. We found both potential for and limitations in the clinical application of ChatGPT to assist in the assessment and management of complex medical conditions. Overall, ChatGPT may serve as a powerful tool to organize medical data in a meaningful and palatable format for medical professionals to reference during patient care.

Pharmacologic Approaches to Suicide Prevention

Suicide is a leading cause of death that is often preventable. This article reviews the role of medications in treating suicidal behavior and in preventing suicide. For an acute suicidal crisis, ketamine, and perhaps esketamine, are emerging as important tools. For patients with chronic suicidality, clozapine remains the only U.S. Food and Drug Administration (FDA) approved antisuicidal medication, and its use is predominantly for patients with schizophrenia and schizoaffective disorder. An abundance of literature supports the use of lithium among patients with mood disorders, including those with major depressive disorder. Despite the black box warning regarding antidepressants and suicide risk among children, adolescents, and young adults, antidepressants are widely used and remain helpful in reducing suicidal thoughts and behaviors, primarily among patients with mood disorders. Treatment guidelines focus on the importance of optimizing treatment of the psychiatric conditions known to be associated with suicide risk. For patients with these conditions, the authors recommend focusing on suicide as an independent treatment target and using an enhanced medication management strategy that includes maintaining a supportive, nonjudgmental therapeutic relationship; flexibility; collaboration; measurement-based care; consideration of combining medications with nonpharmacologic, evidence-based strategies; and ongoing safety planning.

Antipsychotic prescribing practices for outpatients with schizophrenia and reasons for non-clozapine treatment - Data from a Danish quality assessment audit

BACKGROUND

Clozapine is the gold standard for treating treatment-resistant schizophrenia (TRS) although widely underutilised. Both organisational, patient- and clinician related reasons for the underutilisation have been reported, however, the clinical impact of either in real-world settings is not fully elucidated.

AIM

This audit aimed to evaluate the local antipsychotic (AP) prescribing practices for outpatients with schizophrenia and to assess the spectrum and prevalence of journalised reasons for non-clozapine treatment amongst eligible outpatients.

METHODS

Data on demographics, current and former AP treatments, as well as documented reasons for non-clozapine treatment, was extracted through chart audit.

RESULTS

Of the 668 affiliated outpatients with schizophrenia, 43% were treated with AP polytherapy (APP) and 19.6% with clozapine. The most prevalent reason for clozapine discontinuation was related to side effects whereas the most prevalent reason for refusal or omission of clozapine treatment was related to the associated monitoring regimen.

CONCLUSIONS

This audit showed that APP prescribing is a highly prevalent practice in our services when treating outpatients with schizophrenia and that clozapine is underutilised in a 'last resort' manner. The blood-monitoring regimen associated with clozapine treatment was found to be an important factor in the underutilisation. It seemed, however, that the monitoring constituted a barrier for different reasons, requiring different approaches to remedy. Future studies, directly involving both patients and clinicians in the identification and management of the most clinically relevant barriers and their corresponding facilitators, are warranted.

Effects of low-dose combined olanzapine and sertraline on negative and depressive symptoms in treatment-resistant outpatients with acute exacerbated schizophrenia

Background: Treatment-resistant schizophrenia (TRS) is a major clinical challenge. Current antipsychotic medications do not adequately address negative and depressive symptoms in patients with TRS, and novel treatments are thus needed. This study examines the efficacy of low-dose combined olanzapine (OLA) and sertraline on depressive and negative symptoms in patients with TRS. Methods: A total of 34 TRS outpatients with acutely exacerbated schizophrenia were randomly assigned to OLA monotherapy (12.5-20 mg/day) (control group) or low-dose combined OLA (7.5-10 mg/day) and sertraline (50-100 mg/day) (OS group). Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) at baseline and at the end of treatment in weeks 4, 8, 12, and 24. Depressive symptoms and social functioning were also assessed. Results: Compared to the control group, the OS group showed significant improvements in depressive and negative symptoms over time. In addition, the low-dose combination of OLA and sertraline significantly improved social functioning compared with OLA monotherapy. There were no significant between-group differences in psychotic symptom improvement. However, the reduction in Hamilton Depression Rating Scale total score and PANSS negative subscore were not associated with improvements in social functioning, suggesting that these effects of combined treatment are independent. Conclusion: Low-dose combined OLA and sertraline may be effective in the treatment of negative and depressive symptoms compared with standard OLA monotherapy in patients with TRS who are experiencing an acute exacerbation of schizophrenia. Clinical Trial Registration: [ClinicalTrials.gov], identifier [NCT04076371].

Exploration of the Barriers to Clozapine Prescribing in Patients with Treatment-Resistant Schizophrenia: A Qualitative Study

Treatment-resistance schizophrenia (TRS) is one of the psychiatric challenges. While clozapine is an effective treatment for patients with TRS, there are some barriers to clozapine prescribing in these patients. The study aims to explore the barriers from Iranian psychiatrists' points of view. The study was conducted by a qualitative approach using content analysis. The Participants included 12 psychiatrists who were selected purposefully. Data were collected using a semi-structured interview from May to December 2020. All interviews were recorded and transcribed and analyzed qualitatively using constant comparisons. Three main categories emerged concerning barriers to the use of clozapine: drug-related barriers, psychiatrist and health system-related barriers, and patient and family-related barriers. Additionally, specific subcategories within each main category were documented. The present study showed that there are three main groups of barriers to the use of clozapine in patients with TRS. Psychiatrist and health system-related barriers may influence the other two groups of barriers. Further research to investigate the effective strategies to overcome the barriers is recommended.

Clozapine is the approved option in treatment-resistant schizophrenia and requires careful management

Clozapine is the only agent approved for treatment-resistant schizophrenia, but is underprescribed. Its adverse drug event (ADE) profile and patient monitoring requirements can discourage its use, but the benefits of clozapine generally outweigh its risks, as most ADEs are manageable. Careful patient assessment, gradual titration, minimum effective dosages, therapeutic drug monitoring and checks of neutrophils, cardiac enzymes and ADE symptoms are recommended. Neutropenia is common but does not necessarily warrant permanent clozapine cessation.

Evaluation of a collaborative care program for patients with treatment-resistant schizophrenia: Protocol for a multiple case-study. (Preprint)

Background

Approximately one-third of all patients with schizophrenia are treatment resistant. Worldwide, undertreatment with clozapine and other effective treatment options exist for people with treatment-resistant schizophrenia (TRS). In this respect, it appears that regular health care models do not optimally fit this patient group. The Collaborative Care (CC) model has proven to be effective for patients with severe mental illness, both in primary care and in specialized mental health care facilities. The key principles of the CC model are that both patients and informal caregivers are part of the treatment team, that a structured treatment plan is put in place with planned evaluations by the team, and that the treatment approach is multidisciplinary in nature and uses evidence-based interventions. We developed a tailored CC program for patients with TRS.

Objective

In this paper, we provide an overview of the research design for a potential study that seeks to gain insight into both the process of implementation and the preliminary effects of the CC program for patients with TRS. Moreover, we aim to gain insight into the experiences of professionals, patients, and informal caregivers with the program.

Methods

This study will be underpinned by a multiple case study design (N=20) that uses a mixed methods approach. These case studies will focus on an Early Psychosis Intervention Team and 2 Flexible Assertive Community treatment teams in the Netherlands. Data will be collected from patient records as well as through questionnaires, individual interviews, and focus groups. Patient recruitment commenced from October 2020.

Results

Recruitment of participants commenced from October 2020, with the aim of enrolling 20 patients over 2 years. Data collection will be completed by the end of 2023, and the results will be published once all data are available for reporting.

Conclusions

The research design, framed within the process of developing and testing innovative interventions, is discussed in line with the aims of the study. The limitations in clinical practice and specific consequences of this study are explained.

International Registered Report Identifier (IRRID)

DERR1-10.2196/35336