Management of clozapine treatment during the COVID-19 pandemic

Decoding Clozapine-Induced Agranulocytosis: Unraveling Interactions and Mitigation Strategies

Agranulocytosis represents a severe complication associated with the administration of clozapine. Clozapine is an antipsychotic medication that has demonstrated substantial efficacy in remediating refractory schizophrenia and various other psychiatric disorders. Nonetheless, it is crucial to monitor patients for neutropenia regularly during clozapine therapy. Therefore, this article aimed to delve into the prevalence of agranulocytosis during clozapine treatment by scrutinizing the extant literature to discern trends and correlations. This review endeavored to explore factors such as drug interactions, dose-related factors, duration of treatment, and genetic predispositions that could potentially influence the likelihood of patients developing agranulocytosis while undergoing clozapine therapy. Moreover, this review enunciates the ramifications of agranulocytosis on both patients and healthcare providers and meticulously evaluates the strategies to mitigate this risk and ensure optimal patient outcomes.

Vaccination and clozapine use: a systematic review and an analysis of the VAERS database

In the context of COVID-19 concerns related to the potential interactions between clozapine and vaccination arose. With the ultimate goal of deriving recommendations for clinical practice, we systematically reviewed the current evidence regarding altered vaccine effectiveness in clozapine-treated patients and safety aspects of vaccination, such as haematological changes and the impact of vaccines on clozapine blood levels, in clozapine-treated patients. A systematic PRISMA-conform literature search of four databases (PubMed, PsycINFO, EMBASE and Cochrane Library) complemented by a case-by-case analysis of the Vaccine Adverse Event Reporting System (VAERS) database was performed. We then systematically appraised the joint evidence and tried to derive recommendations for clinical practice. 14 records were included in this analysis. These records consisted of 5 original articles and 9 case reports. Among the original articles, two studies provided data on the association between clozapine use and antibody responses to vaccination, both indicating that clozapine use in schizophrenia may be associated with reduced levels of immunoglobulins. Additionally, three studies examined vaccine safety in clozapine-treated patients, with no clinically significant adverse effects directly attributable to the interplay between vaccinations and clozapine. VAERS Analysis encompassed 137 reports and showed no consistent evidence of an increased risk for clozapine blood level increases or adverse events. We found no evidence indicating that clozapine impairs the effectiveness of vaccines. Moreover, no serious safety concerns seem to apply when patients on clozapine are receiving vaccines. However, it is crucial to acknowledge that data on the interaction between clozapine and vaccines remain limited.

Clozapine Serum Concentrations Are Disrupted by SARS-CoV-2 Vaccinations

This paper reports the case of a 27-year-old man with paranoid schizophrenia who was finally stabilized on clozapine medication. After vaccination against severe acute respiratory syndrome coronavirus 2, serum levels of clozapine increased. It is well established that immune responses can trigger cytokine cascades affecting drug metabolism, which, in the case of clozapine treatment, can lead to severe intoxication.

Myocarditis in patients on long-term antipsychotics -mechanism, management and recent updates

Objective

Clozapine is the first atypical antipsychotic drug and was frequently cited as the most effective antipsychotic for treatment-resistant schizophrenia, but it is associated with a concert of significant cardiotoxic side effects. Clozapine-induced Myocarditis (CIM) is diagnosed based on the combination of clinical symptoms, laboratory investigations, radiological findings, and sometimes biopsy. The literature on CIM management and clinical consensus on the best course of action is mixed.

Methodology

An all-language literature search on Medline, Cochrane, Embase, and Google Scholar until April 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "CIM," "clozapine," "cardiotoxicity," and "myocarditis." We explored the literature on CIM for its pathophysiology, diagnosis, monitoring, and management.

Results

The clinical features of CIM may be highly variable, ranging from asymptomatic disease to fulminant heart failure, and cessation of medication was the mainstay treatment of CIM, followed by supportive therapy. Other antipsychotics have also been linked with cardiotoxic side effects.

Conclusion

Despite being the most effective antipsychotic, clozapine is associated with a cardiotoxic side effect. Current literature suggests that these antipsychotic-related cardiotoxic events impact the treatment selection for schizophrenia and other psychotic disorders, and they must be kept in mind while designing new treatment protocols in the future.

Clozapine Therapy and COVID-19: A Systematic Review of the Prevalence Rates, Health Outcomes, Hematological Markers, and Patient Perspectives

BACKGROUND/OBJECTIVES

There have been concerns that clozapine treatment may undermine the capacity of the body to fight infection and increase the vulnerability to contracting COVID-19. This review of recent cohort studies investigated (1) whether people with a severe psychiatric disorder are at increased risk of COVID-19 and complications, (2) the immunological response of clozapine-users who contract COVID-19, and (3) patients' perspectives on COVID-19 and the pandemic response.

METHODS

A systematic search of EMBASE, Medline, Pubmed, and PsycINFO databases using PRISMA guidelines using "COVID-19", "clozapine", and "vaccination" terms.

RESULTS

18 studies (out of 330 identified) met all criteria (N = 119 054 including 8045 on clozapine). There was no strong evidence that clozapine users may be at increased risk of contracting COVID-19 or developing complications after adjusting for medical comorbidities. Hematological studies showed temporary reductions in neutrophils in COVID-19-positive patients and vaccination suggesting a clozapine effect in defence against infection. Vaccination studies did not report major adverse effects. Increased plasma levels of clozapine and neutropenia however point to COVID-19-related interference of clozapine metabolism. Patient surveys reported limited impact on mental health and positive attitudes regarding pandemic response.

CONCLUSION

This review did not find compelling evidence that the immune system of clozapine users put them at risk of COVID-19 and further complications. Evidence of drug-infection interactions however points to the importance of adhering to consensus guidelines about clozapine therapy during the pandemic. More evidence using longitudinal designs is required to examine the longer-term effects of COVID-19 and vaccination in this vulnerable population.

Neutropenia in Patients With Clozapine-Treated Schizophrenia: An Effect of Clozapine or a Consequence of SARS-CoV-2 Infection? A Systematic Review

BACKGROUND

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia. Despite its therapeutic benefits, it is still widely underused, mainly because of its potential to cause agranulocytosis and neutropenia. Prescribing clozapine in COVID-19-positive patients became more challenging because of this potential side effect. This article is a review of literature on the risk of neutropenia associated with clozapine treatment in patients with COVID-19.

AREAS OF UNCERTAINTY

In clozapine-treated COVID-19-positive patients, neutropenia was reported in some cases; is it a consequence of clozapine treatment or of SARS-Co2 infection?

DATA SOURCES

Data were extracted from 2 databases: PubMed/MEDLINE and Google Scholar. We selected all original reports, from March 2020 until May 2022, on neutropenia associated with clozapine treatment in positive COVID-19 patients. Eleven studies were selected for the final analysis.

THERAPEUTIC ADVANCES

Before the COVID-19 pandemic, neutropenia in clozapine-treated patients was reported in 3.8% of cases. During the pandemic, neutropenia rates seemed to be higher. As per the cause of neutropenia, studies reported contradictory results. We aim to clarify rates and causes of neutropenia in clozapine-treated COVID-19-positive patients.

RESULTS

Three hundred eighty-eight articles were initially selected from the 2 databases. After excluding duplicates, unrelated articles, reviews, and guidelines, 11 studies were analyzed, all centered on clozapine treatment, COVID-19 infection, and associated neutropenia.

CONCLUSIONS

Clozapine treatment in COVID-19-positive patients may be associated with a transient reduction of absolute neutrophils count, in some cases reaching neutropenia levels. Neutropenia rates reported in SARS-CoV-2-infected patients are higher than the prepandemic reports; therefore, we assume that the cause might be a result of the immunological interference between clozapine and SARS-CoV-2. Clozapine treatment needs to be continued whenever possible, with dose adjustments in relation to blood test results.

Clozapine and Neutropenia in Patients with Schizophrenia and SARS-CoV-2 Infection

BACKGROUND

Clozapine (CLZ) is used for treatment-resistant schizophrenia (TRS). Adverse reactions to clozapine include neutropenia. In March 2020, WHO declared the COVID-19 pandemic and after, psychiatrists raised concerns regarding continuation of clozapine, due to multiple restrictions. We aimed to provide a study on the association between neutropenia and clozapine in patients with schizophrenia and COVID-19.

AIM

To assess the neutrophil count in patients with schizophrenia treated with clozapine and infected with COVID-19.

METHODS

The study patients with schizophrenia, according to DSM-5, admitted to the Clinical Hospital of Psychiatry and Neurology Brasov, Romania, between April 2020 and October 2021. The inclusion criteria included positive RT-PCR (real-time PCR) test for COVID-19 and treatment with clozapine. We assessed three values of ANC (absolute neutrophil count): before COVID-19 infection (last ANC obtained at mandatory check), during infection and 1 month after resolution (first negative PCR test).

RESULTS

Of the 105 cases, 95 did not have neutropenia. Fifty-nine patients were males (62.1%), mean age was 43.5 years (SD = 12.1) with an average of clozapine treatment of 52.4 months (SD = 11.9). At baseline, they had a small reduction in the ANC mean value (4.41 × 109/l; SD = 2.22) which did not constitute a statistically significant decline from the prior to COVID-19 mean value of 4.66 × 109/l (SD = 2.34; p = 0.45). Values were also normal in the first month after negative PCR testing (4.45 × 109/l; SD = 2.35; p = 0.91). A total of 10 patients (9.5%) had neutropenia. The age, dose of clozapine and duration of treatment were not statistically different compared to the group without neutropenia.

CONCLUSION

Psychiatrists and other health professionals should keep in mind that neutrophil count may decrease during COVID-19 infection in patients taking clozapine and in some cases, neutropenia may even occur. We assumed that neutropenia could be caused by COVID-19 and clozapine interaction.

Clozapine treatment and risk of severe COVID-19 infection

OBJECTIVE

To investigate whether patients with clozapine treatment are at an increased risk of a more severe COVID-19 infection as compared with patients on other antipsychotic drugs.

METHODS

In this register-based cohort study, all residents (age 18 or older) in the Stockholm Region with a psychotic disorder diagnosis and antipsychotic treatment were included (N = 8 233) and followed from 1 March 2020 to 14 January 2021. The exposure was defined as clozapine treatment and the outcome measures (indicating a more severe COVID-19 infection) were: inpatient care, care within intensive care unit or death due to COVID-19 infection. Differences in outcome rates between exposed (n = 966) and unexposed (other antipsychotics; n = 7 267) were examined using Cox proportional hazards models and expressed as hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

No statistically significant differences in outcome rates were found between the two groups of patients after adjusting for age, sex and residence in retirement homes. The adjusted HR for the exposed compared to the unexposed was 0.96 (95% CI: 0.54, 1.70) for inpatient care; 1.69 (0.48, 5.93) for care in intensive care unit (ICU); and 0.86 (0.26, 2.80) for death. Regarding inpatient care, additional adjusting for country of birth, living in socioeconomically vulnerable areas, number of care visits during the previous year, and comorbid medical illnesses did not alter the results.

CONCLUSIONS

Our results may add support to the present guidelines, recommending sustained clozapine treatment during the current COVID-19 pandemic with careful monitoring and readiness to alter drug doses as needed.

Challenges in Prescribing Clozapine in the Era of COVID-19: A Review Focused on Immunological Implications

The global COVID-19 pandemic has disrupted every aspect of the healthcare system. Apart from the issues surrounding COVID-19 itself, care for existing patients has met many challenges. One such challenge is caring for patients who are on clozapine treatment and have been confirmed positive for COVID-19. Schizophrenia has been considered to have a deep connection with the immune system, and clozapine can induce further changes in this system. COVID-19 can ravage the compromised immune system and aggravate tissue damage. The intricate relations between schizophrenia, clozapine, and COVID-19 make it difficult to predict the clinical course of COVID-19 in clozapine-treated patients. However, the rigid prohibition on using clozapine if COVID-19 is confirmed may harm patients. Patients who have to use clozapine are often refractory cases with no alternatives. Therefore, the decision to maintain or stop clozapine must be made after a comprehensive review of the patient’s unique situation. To do this, theoretical and practical issues surrounding the use of clozapine in COVID-19 should be reviewed and discussed. In this review, we gather useful information surrounding this issue and present an overview. Focusing on the immune system, various theoretical possibilities that could arise from schizophrenia, clozapine, and COVID-19 were carefully examined, and practical checklists for the care of these patients were explored. It is hoped that this review will convince many clinicians to pay attention to this momentous issue and facilitate more active sharing of clinical experiences.

Risk mitigation with the use of clozapine - Quo vadimus

The risk of neutropenia decreases significantly after the first year of clozapine initiation, and indefinite hematological monitoring is increasingly questioned. Despite comparable risks of neutropenia, the guidelines for antithyroid drugs - carbimazole and propylthiouracil do not recommend routine hematological monitoring. Assuming a similar pathogenic mechanism, data from antithyroid drugs indicate that neutropenia develops rapidly, and indefinite hematological monitoring misses a large majority of cases in the pre-symptomatic phase. Hence, a more pragmatic strategy of intensive hematological monitoring in the first year of clozapine initiation followed by selective haematological monitoring in case of febrile illnesses or pharyngitis needs to be explored.

Schizophrenia during the COVID-19 pandemic

PURPOSE OF REVIEW

The coronavirus disease 19 (COVID-19) pandemic is having a critical impact on healthcare systems across the world, as well as on mental health in the general population; however, evidence regarding the impact of the COVID-19 pandemic on people living with schizophrenia and on the onset of psychotic symptoms is currently emerging.

RECENT FINDINGS

People living with schizophrenia are at an increased risk of COVID-19 and present worse COVID-19-related outcomes, including mortality. They show low levels of information and of concern regarding the possibility of contagion and infection but presented substantially stable levels of psychotic symptoms and even increased subjective well being during the pandemic. SARS-CoV-2, as well as the prolonged social isolation and the spread of misinformation, appear to be responsible in some cases for the onset of psychotic symptoms.

SUMMARY

Clinicians should inform and educate their patients on the risks related to SARS-CoV-2 infection and COVID-19 and on the precautions that they should adopt to avoid contagion. Particular attention should be devoted to maintaining the continuity of care, especially in frail patients. Telemedicine might represent a valid support, but face-to-face visits in some cases remain essential. The hypothesis of a direct role of viral infection on the onset of psychotic disorders is currently debated, as viral involvement of central nervous system appears to be rather infrequent in COVID-19.

Clozapine, neutropenia and Covid-19: should clinicians be concerned? 3 months report

BACKGROUND

Clozapine is among the most effective antipsychotics used for treatment resistant schizophrenia. Adverse reactions to clozapine include neutropenia. In March 2020, at the start of the Coronavirus -19 pandemic, clinicians raised concerns regarding continuation of antipsychotic treatment, and specifically of clozapine, in patients with coronavirus disease. We aimed here at providing a short report focusing on the association between neutropenia and clozapine in a case series of psychiatric inpatients diagnosed with COVID-19.

PATIENTS & METHODS

We retrospectively inspected data of 10 patients on clozapine, admitted to Highgate Mental Health Centre, Camden & Islington NHS Foundation Trust, between March and July 2020; selection was based on their COVID-19 positive PCR test. We used a linear regression model to estimate whether there was a significant drop in the neutrophil count during SARS-CoV-2 infection.The analysis was done in R using a linear regression to the origin.

RESULTS

Data were collected on 10 patients, of which 7 were males. During COVID-19 infection, neutrophils' count (ANC) was 4.13 ​× ​109/l (SD ​= ​2.70) which constituted a significant drop from a baseline value of 5.2 ​× ​109/l (SD ​= ​2.24). The mean relative reduction in ANC was -0.2729 (SD ​= ​0.1666). The beta value of 0.8377 obtained with the linear regression showed that ANC values during SARS-CoV-2 infection were 83.77% of the baseline ANC showing that within the two time points there was a decrease of 16.23%. The linear regression had a pvalue ​= ​8.96 ​× ​10-8 and an adjusted R2 of 95.94% which shows that the variability of the data is very well explained by the model. We also compared baseline ANC with ANC values approximately a month after resolution of the infection and results indicate that ANC values return to a 95% of baseline.

CONCLUSIONS

Clinicians should bear in mind that a significant drop in neutrophils' count may occur in patients taking clozapine and affected from a SARS-CoV-2 infectionand that this drop is only transitory.

COVID-19 infection causes a reduction in neutrophil counts in patients taking clozapine

BACKGROUND

Monitoring of white cell counts during clozapine treatment leads to cessation of therapy if levels fall below predetermined values. Reductions in white cell counts, driven by lower levels of lymphocytes, have been observed with coronavirus disease 2019 (COVID-19). Neutropenia during COVID-19 has not been reported. We present data for 56 patients who were taking clozapine and had COVID-19.

METHODS

We included patients who were taking clozapine at the time they tested positive for COVID-19. We compared absolute neutrophil counts, lymphocyte counts and white cell counts between baseline and the first week of infection, and baseline and the second week of infection.

RESULTS

We observed reductions in absolute neutrophil counts (p = 0.005), lymphocyte counts (p = 0.003) and white cell counts (p < 0.001) between baseline and the first 7 days of COVID-19. All cell counts had returned to baseline levels by days 8 to 14. Six patients experienced neutropenia (absolute neutrophil counts < 2.0 × 109/L) and of those, 4 underwent mandatory cessation of clozapine. For 3 patients, clozapine treatment had been established for more than 6 months with no previous neutropenia, neutrophil levels returned to baseline within 2 weeks and no further neutropenia was observed on restarting treatment.

LIMITATIONS

This was a retrospective chart review; larger cohorts are required. Clozapine plasma levels were largely not measured by clinicians.

CONCLUSION

These data strongly suggest that mild neutropenia in the acute phase of COVID-19 in patients who are well established on clozapine is more likely to be a consequence of the virus than of clozapine treatment.

Implications of the COVID-19 pandemic for patients with schizophrenia spectrum disorders: narrative review

BACKGROUND

COVID-19 was declared a pandemic in March 2020, by the World Health Organization. The pandemic has had unprecedented worldwide implications, in particular on marginalized populations.

AIMS

The aim of this study is to review the impact of the pandemic on patients with schizophrenia spectrum disorders.

METHOD

A number of databases were searched for this review, including PubMed, EMBASE, PsycINFO and Google Scholar. Search terms included psychosis and COVID-19, schizophrenia and COVID-19, and severe mental illness and COVID-19. We included all English language papers and preprints. The final search was done on 15 July 2020.

RESULTS

Forty-seven relevant studies were identified and included in this review. Studies were summarised into five main subcategories: potential impact of the COVID-19 pandemic on physical health outcomes of patients with schizophrenia spectrum disorders, impact on mental health outcomes, review of case reports and case series to date, treatment recommendation guidelines and risk of increased prevalence of psychosis.

CONCLUSIONS

Patients with schizophrenia spectrum disorders may be vulnerable to the effects of the COVID-19 pandemic. This patient population has a number of risk factors, including psychosocial adversities and illness related factors. Continuous monitoring and long-term studies of the impact of the pandemic on this patient population are required.

Rehabilitation During a Pandemic: Psychiatrists as First Responders?

The South London and Maudsley Community Rehabilitation Psychiatry team aims to provide long-term and holistic care to patients with enduring mental illness. This letter concisely outlines our response to the coronavirus pandemic, including the standard operating procedure we introduced and, at a trust level, the changes made to clozapine monitoring. We were surprised by the expectations of our patients during the pandemic: we found that unwell patients or their carers would contact our service first, ahead of 111, primary care or emergency services for advice and treatment. In response, we took on a deliberative first-responder role. Perhaps this is to be expected for a specialty that provides holistic long-term care to its patients. We think this is of interest to other mental health teams, primary care, community psychiatry teams and the lay reader.

A Basic Review of the Preliminary Evidence That COVID-19 Risk and Severity Is Increased in Vitamin D Deficiency

As the world's attention has been riveted upon the growing COVID-19 pandemic, many researchers have written brief reports supporting the hypothesis that vitamin D deficiency is related to the incidence and severity of COVID-19. The clear common thread among the top risk groups-vitamin D deficiency-may be being overlooked because of previous overstated claims of vitamin D benefits. However, the need to decrease COVID-19 fatalities among high-risk populations is urgent. Early researchers reported three striking patterns. Firstly, the innate immune system is impaired by vitamin D deficiency, which would predispose sufferers to viral infections such as COVID-19. Vitamin D deficiency also increases the activity of the X-chromosome-linked "Renin-Angiotensin" System, making vitamin D deficient individuals (especially men) more susceptible to COVID-19's deadly "cytokine storm" (dramatic immune system overreaction). Secondly, the groups who are at highest risk for severe COVID-19 match those who are at highest risk for severe vitamin D deficiency. This includes the elderly, men, ethnic groups whose skin is naturally rich in melanin (if living outside the tropics), those who avoid sun exposure for cultural and health reasons, those who live in institutions, the obese, and/or those who suffer with hypertension, cardiovascular disease, or diabetes. And thirdly, the pattern of geographical spread of COVID-19 reflects higher population vitamin D deficiency. Both within the USA and throughout the world, COVID-19 fatality rates parallel vitamin D deficiency rates. A literature search was performed on PubMed, Google Scholar, and RSMLDS, with targeted Google searches providing additional sources. Although randomized controlled trial results may be available eventually, the correlational and causal study evidence supporting a link between vitamin D deficiency and COVID-19 risks is already so strong that it supports action. The 141 author groups writing primarily about biological plausibility detailed how vitamin D deficiency can explain every risk factor and every complication of COVID-19, but agreed that other factors are undoubtedly at work. COVID-19 was compared with dengue fever, for which oral vitamin D supplements of 4,000 IU for 10 days were significantly more effective than 1,000 IU in reducing virus replication and controlling the "cytokine storm" (dramatic immune system over-reaction) responsible for fatalities. Among the 47 original research studies summarized here, chart reviews found that serum vitamin D levels predicted COVID-19 mortality rates (16 studies) and linearly predicted COVID-19 illness severity (8 studies). Two causal modeling studies and several analyses of variance strongly supported the hypothesis that vitamin D deficiency is a causal, rather than a bystander, factor in COVID-19 outcomes. Three of the four studies whose findings opposed the hypothesis relied upon disproven assumptions. The literature review also found that prophylactically correcting possible vitamin D deficiency during the COVID-19 pandemic is extremely safe. Widely recommending 2,000 IU of vitamin D daily for all populations with limited ability to manufacture vitamin D from the sun has virtually no potential for harm and is reasonably likely to save many lives.

Clozapine prescribing in COVID-19 positive medical inpatients: a case series

There is both uncertainty regarding the safety of clozapine in COVID-19 patients owing to limited published data and a lack of consensus on continuing clozapine in patients with severe respiratory infections. COVID-19 is known to induce an acute immune response which can affect haematological parameters associated with clozapine monitoring, and systemic infection may reduce clozapine clearance. Clozapine, which has been associated with worse outcomes in some pneumonias, may in theory worsen outcomes in COVID-19. Despite these concerns, there are some data to indicate it is safe to continue clozapine in COVID-19 infection. In this retrospective case series, we describe our experiences of clozapine prescribing and disease progression of eight SARS-CoV-2 positive patients on medical wards in a major London teaching hospital. In four cases clozapine was stopped during the hospital admission. A COVID-19 pneumonia developed in four patients: three of these required intensive care unit admission for an average of 34 days. At the time of writing, three patients had died (two directly from COVID-19 pneumonia), two remained in general hospital wards, two were recovering in the community and one had been transferred to an inpatient psychiatric hospital. Follow-up length varied but in each case was not more than 104 days. Delirium was the most common adverse neuropsychiatric event, and in one case a relapse of psychosis occurred after cessation of clozapine. This retrospective case series illustrates the safe use of clozapine during COVID-19 infection. Our experiences suggest that consideration should be made to continuing clozapine even in those most unwell with COVID-19. We also identify areas which require larger scale hypothesis-testing research.

The effect of COVID-19 on absolute neutrophil counts in patients taking clozapine

Clozapine is associated with haematological side effects, including neutropaenia, which can signal impending life-threatening agranulocytosis. Patients with COVID-19 infection frequently experience lymphopaenia, but not neutropaenia. We present 13 patients established on clozapine who developed COVID-19 infection. There were no significant differences in total white cell or neutrophil counts between pre-COVID-19, intra-COVID-19 or post-COVID-19 periods. We therefore suggest that patients who develop COVID-19 should generally have their clozapine treatment continued. Patients taking clozapine who develop neutroapaenia during COVID-19 infection should be investigated and monitored as in normal practice, because changes in neutrophil counts cannot be assumed to be due to the viral infection.