Benign ethnic neutropenia: what is a normal absolute neutrophil count?

Lower Neutrophil Count Without Clinical Consequence Among Children of African Ancestry Living With HIV in Canada

OBJECTIVE

To investigate the association between African ancestry and neutrophil counts among children living with HIV (CLWH). We also examined whether medications, clinical conditions, hospitalization, or HIV virologic control were associated with low neutrophil counts or African ancestry.

DESIGN

We conducted a secondary analysis of the Early Pediatric Initiation Canada Child Cure Cohort (EPIC4) Study, a multicenter prospective cohort study of CLWH across 8 Canadian pediatric HIV care centers.

METHODS

We classified CLWH according to African ancestry, defined as "African," "Caribbean," or "Black" maternal race. Longitudinal laboratory data (white blood cells, neutrophils, lymphocytes, viral load, and CD4 count) and clinical data (hospitalizations, AIDS-defining conditions, and treatments) were abstracted from medical records.

RESULTS

Among 217 CLWH (median age 14, 55% female), 145 were of African ancestry and 72 were of non-African ancestry. African ancestry was associated with lower neutrophil counts, white blood cell counts, and neutrophil-lymphocyte ratios. Neutrophil count <1.5 × 109/L was detected in 60% of CLWH of African ancestry, compared with 31% of CLWH of non-African ancestry (P < 0.0001), representing a 2.0-fold higher relative frequency (95% CI: 1.4-2.9). Neutrophil count was on average 0.74 × 109/L (95% CI: 0.45 to 1.0) lower in CLWH of African ancestry (P < 0.0001). Neither neutrophil count<1.5 × 109/L nor African ancestry was associated with medications, hospitalizations, AIDS-defining conditions, or markers of virologic control (viral load, sustained viral suppression, and lifetime nadir CD4).

CONCLUSIONS

In CLWH, African ancestry is associated with lower neutrophil counts, without clinical consequences. A flexible evaluation of neutrophil counts in CLWH of African ancestry may avoid unnecessary interventions.

Neutropenia in Childhood-A Narrative Review and Practical Diagnostic Approach

Neutropenia refers to a decrease in the absolute neutrophil count according to age and race norms and poses a common concern in pediatric practice. Neutrophils serve as host defenders and act crucially in acute inflammation procedures. In this narrative review, we systematically present causes of neutropenia in childhood, mainly adopting the pathophysiological classification of Frater, thereby studying (1) neutropenia with reduced bone marrow reserve, (2) secondary neutropenia with reduced bone marrow reserve, and (3) neutropenia with normal bone marrow reserve. Different conditions in each category are thoroughly discussed and practically approached from the clinician's point of view. Secondary mild to moderate neutropenia is usually benign due to childhood viral infections and is expected to resolve in 2-4 weeks. Bacterial and fungal agents are also associated with transient neutropenia, although fever with severe neutropenia constitutes a medical emergency. Drug-induced and immune neutropenias should be suspected following a careful history and a detailed clinical examination. Cytotoxic chemotherapies treating malignancies are responsible for severe neutropenia and neutropenic shock. Rare genetic neutropenias usually manifest with major infections early in life. Our review of taxonomies clinical findings and associates them to specific neutropenia disorders. We consequently propose a practical diagnostic algorithm for managing neutropenic children.

Understanding clozapine-related blood dyscrasias. Developments, genetics, ethnicity and disparity: it's a CIN

Clozapine remains the gold standard intervention for treatment-resistant schizophrenia; however, it remains underused, especially for some minority groups. A significant impediment is concern about propensity to neutropenia. The aim of this article is to provide an update on current knowledge relating to: the pattern and incidence of severe blood dyscrasias; the effectiveness of current monitoring regimes in reducing harm; the mechanisms of and the distinctions between clozapine-induced neutropenia and agranulocytosis; benign ethnic neutropenia; and changes to the monitoring thresholds in the USA and other international variations. These all have implications for the practical use of clozapine; specifically, how barriers to initiating, maintaining and restarting clozapine can be understood and in many cases overcome, especially for patients from minority groups, potentially with simpler approaches than the use of lithium or G-CSF.

Clozapine and neutrophil response in patients of African descent: A six-month, multinational, prospective, open-label clinical trial

INTRODUCTION

Clozapine is the most effective antipsychotic for treatment-resistant schizophrenia, but it is markedly underutilized, particularly in the US Black population, partly because of concern over clozapine-associated low absolute neutrophil count (ANC). People of African descent have a lower normative ANC range than the White population, which is associated with a specific "ACKR1-null" ("Duffy null") CC genotype (SNP rs2814778) on the ACKR1 gene, termed benign ethnic neutropenia (BEN). The range of ANC variability and safety of clozapine have not been established in people with BEN or examined prospectively in people of African descent.

METHODS

We completed a multisite, 6-month, prospective, open-label clinical trial of clozapine treatment in people of African descent with schizophrenia spectrum disorders for whom clozapine was clinically indicated, with or without the ACKR1-null genotype. We examined clozapine safety and weekly ANC during clozapine treatment and evaluated ANC variability by ACKR1-null genotype, sex, study site, and clozapine dosing using repeated measures analysis of covariance. Genotype was assayed using TaqMan® technology.

RESULTS

We enrolled 274 participants, of whom 227 (82.8 %) completed 6 months of clozapine treatment. There was one case of severe neutropenia (<500 cells/mm3) (0.36 %) over 1467.6 person-months of clozapine exposure. This participant recovered without sequelae after discontinuation of clozapine. Of the 249 participants with known genotypes, 199 (79.9 %) had the ACKR1-null genotype. Neutropenia (<1500 cells/mm3) occurred significantly more often in the ACKR1-null group (33 % [65/199]) than in those with the T allele (6 % (3/50); p < 0.001). Fourteen (5 %) patients discontinued due to adverse events. Rates of infection and fever were low and sialorrhea was the commonest side effect (N = 187, 68 %).

CONCLUSION

To our knowledge, this is the largest prospective clozapine trial in people of African descent. Severe neutropenia was rare, despite the high prevalence (80 %) of the ACKR1-null genotype. Our findings suggest that clozapine can be used safely in Black patients including those with BEN.

Safety of BEN guidelines in clozapine treatment: A Canadian perspective

OBJECTIVE

Unidentified benign ethnic neutropenia (BEN) has been recognized as a factor contributing to clozapine underutilization and discontinuation. Guidelines were implemented to accommodate BEN in Canada, and our main objective was to evaluate clozapine's safety in a sample of Canadian psychiatric patients with BEN.

METHOD

A retrospective chart review was conducted at the Centre for Addiction and Mental Health, Toronto, Canada. Through the clozapine clinic registry, participants were identified who (i) received clozapine using the approved BEN guidelines for hematological monitoring, and (ii) had at least one complete blood count pre- and post-clozapine initiation.

RESULTS

Our sample population was comprised of 41 BEN patients who were African-Caribbean (49 %), African (34 %), African-North American (12 %), Middle Eastern (2 %), and Indian-Caribbean (2 %). There was a significant reduction in hematological alerts for these patients while monitored under BEN guidelines (p < 0.001). The mean within-patient ANC value was not significantly different one year after clozapine initiation compared to the pre-clozapine baseline (p = 0.069). None of the patients discontinued clozapine for hematological reasons.

CONCLUSIONS

Findings demonstrated that patients monitored under the modified hematological guidelines for BEN can be safely treated with clozapine. These findings have important clinical ramifications as increased implementation of BEN guidelines may allow for broader use of clozapine.

Duffy-Null Phenotype-Associated Neutropenia is the Most Common Etiology for Leukopenia/Neutropenia Referrals to a Tertiary Children's Hospital

Duffy-null phenotype-associated neutropenia was present in 77.7% of leukopenia/neutropenia referrals to our center in Detroit with a high prevalence in Yemeni (96.6%), African American (91%), and non-Yemeni Middle Eastern (52.9%) patients. Greater availability of Duffy typing in patients with neutropenia but without recurrent/frequent/serious infections may lessen the need for additional consultations and investigations.

Clinical outcomes of patients referred for asymptomatic neutropenia: A focus on racial disparities in hematology

BACKGROUND

Asymptomatic neutropenia is a common hematology referral, though standardized reference ranges and published clinical outcomes are lacking.

METHODS

In our retrospective analysis, we evaluated demographics, laboratory, and clinical outcomes of adult patients referred to an academic hematology practice for evaluation of neutropenia from 2010 to 2018. Primary and secondary outcomes included incidence of hematologic disorders and rates of Duffy-null positivity by race, respectively. In a separate analysis, we reviewed absolute neutrophil count (ANC) reference ranges from publicly available Association of American Medical Colleges Medical School Member laboratory directories to assess institutional variations.

RESULTS

In total, 163 patients were included, with disproportionate number of Black patients referred compared to local demographics. Twenty-three percent of patients (n = 38) were found to have a clinically relevant hematologic outcome (mean ANC of 0.59 × 109 /L), and only six were identified with ANC ≥1.0 × 109 /L. Incidence of hematologic outcomes was lowest among Black patients (p = .05), and nearly all Blacks who underwent Duffy-null phenotype testing were positive (93%), compared to 50% of Whites (p = .04). In separate review of laboratory directories, we confirmed wide variation in ANC lower limit of normal (0.91-2.40 × 109 /L).

CONCLUSION

Hematologic disorders were rare in patients with mild neutropenia and among Blacks, highlighting the need to standardize hematological ranges representative of non-White communities.

Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation: a WorldWide Antimalarial Resistance Network individual patient data meta-analysis

BACKGROUND

The World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance.

METHODS

Uncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/µL and age-stratified values) using estimates derived from the measured WBC value as reference.

RESULTS

Eighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (× 1000 cells/µL) in age groups < 1, 1-4, 5-14 and ≥ 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/µL resulted in parasite density underestimation by a median (IQR) of 26% (4-41%) in infants < 1 year old but an overestimation by 50% (16-91%) in adults aged ≥ 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve precision of parasitaemia estimation. Imprecision of parasite clearance estimates was only affected by the within-patient WBC variability over time, and remained < 10% for 79% of patients.

CONCLUSIONS

Using an assumed WBC value for parasite density estimation from a thick smear may lead to underdiagnosis of hyperparasitaemia and could adversely affect clinical management; but does not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance.

Outcome of COVID-19 mRNA Vaccination in Patients Treated With Clozapine WHO Previously Went Through SARS-COV-2 Infection

BACKGROUND

The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic had multiple consequences for the health care system, especially for patients with mental illnesses. Schizophrenia patients particularly appear to have a higher risk of complications due to coronavirus-19 (COVID-19). Clozapine remains the gold standard for treatment-resistant schizophrenia (TRS). However, the COVID-19 pandemic had an important negative impact on clozapine treatment, mainly because of its administration protocol, which was very difficult to follow during the restrictions imposed in the pandemic, and its side effects in patients with COVID-19 infection. Vaccination is an effective method of avoiding SARS-CoV-2 infection or its severe complications, especially in susceptible populations. Data on adverse events after vaccination against COVID-19 are limited, both in the general population and in schizophrenia patients.

STUDY QUESTION

The study aimed to investigate the safety of COVID-19 vaccination in patients treated with clozapine for hematological parameters.

STUDY DESIGN

We conducted an analytical cross-sectional study between July 1, 2021, and June 30, 2022. We compared 2 groups of COVID-19 vaccinated patients who had previously experienced SARS-CoV-2 infection: The first group was treated with clozapine, whereas the second group was treated with other antipsychotics.

MEASURES AND OUTCOMES

The primary objective was to identify granulocytopenia, leukocytopenia, and lymphocytopenia. The results were measured after the second dose of the Pfizer-BioNTech vaccine.

RESULTS

This study included 100 patients. White blood cell count changes were limited to a few cases of mild granulocytopenia (8.16% in the clozapine group and 3.92% in the nonclozapine group, P = 0.37) with no cases of severe granulocytopenia or agranulocytosis.

CONCLUSIONS

As far as leukocyte counts are concerned, mRNA COVID-19 vaccination seems to be safe in patients treated with clozapine who previously had SARS-CoV-2 infection. Leukocyte changes had no clinical implications.

Re-examining the utility and validity of benign ethnic neutropenia: A narrative literature review

OBJECTIVE

To conduct a narrative literature review of published evidence documenting racial differences in white blood cells (WBCs) resulting in the legitimization of benign ethnic neutropenia (BEN) as a diagnosis.

METHOD

A search of English-language U.S.-based articles was undertaken using the following electronic databases: Medline (1860 to 1990); PsycINFO (1860 to 1990); and EMBASE (1860 to 1990), which resulted in a total of eight studies. A narrative literature review of the eight studies was conducted to assess how race was utilized in the study methods.

RESULTS

Of the eight studies, several themes emerged within the scientific literature that demonstrate imprecise, problematic use of race in research practice. 1) Researchers embedded flawed notions of biological differences between racial groups (mostly focused on Black people compared to white people) within the research hypotheses, methods, and conclusions, 2) studies were unclear on how racial group membership was defined and identified within the study samples, 3) studies did not adequately account for structural or historical determinants of health that may drive racial differences in immune status (i.e., neutropenia).

CONCLUSIONS

Given the limitations in this U.S.-based scientific literature, BEN is a diagnosis of limited construct validity that reinforces false notions of biological race, warrants renaming to remove "ethnic" language (to include "familial" or "hereditary"), and suggests a need for global expansion of the existing absolute neutrophil count reference ranges in the clozapine monitoring guidelines.

Privacy-Aware Early Detection of COVID-19 Through Adversarial Training

Early detection of COVID-19 is an ongoing area of research that can help with triage, monitoring and general health assessment of potential patients and may reduce operational strain on hospitals that cope with the coronavirus pandemic. Different machine learning techniques have been used in the literature to detect potential cases of coronavirus using routine clinical data (blood tests, and vital signs measurements). Data breaches and information leakage when using these models can bring reputational damage and cause legal issues for hospitals. In spite of this, protecting healthcare models against leakage of potentially sensitive information is an understudied research area. In this study, two machine learning techniques that aim to predict a patient's COVID-19 status are examined. Using adversarial training, robust deep learning architectures are explored with the aim to protect attributes related to demographic information about the patients. The two models examined in this work are intended to preserve sensitive information against adversarial attacks and information leakage. In a series of experiments using datasets from the Oxford University Hospitals (OUH), Bedfordshire Hospitals NHS Foundation Trust (BH), University Hospitals Birmingham NHS Foundation Trust (UHB), and Portsmouth Hospitals University NHS Trust (PUH), two neural networks are trained and evaluated. These networks predict PCR test results using information from basic laboratory blood tests, and vital signs collected from a patient upon arrival to the hospital. The level of privacy each one of the models can provide is assessed and the efficacy and robustness of the proposed architectures are compared with a relevant baseline. One of the main contributions in this work is the particular focus on the development of effective COVID-19 detection models with built-in mechanisms in order to selectively protect sensitive attributes against adversarial attacks. The results on hold-out test set and external validation confirmed that there was no impact on the generalisibility of the model using adversarial learning.

Health inequalities in the management of chronic hepatitis B virus infection in patients from sub-Saharan Africa in high-income countries

Chronic hepatitis B virus disproportionately affects migrant communities in high-income countries, reflecting increased migration from sub-Saharan Africa. Chronic hepatitis B virus is endemic in sub-Saharan Africa, yet the natural history of chronic infection experienced by patients remains incompletely understood, with evidence of variability across genotypes and regions within sub-Saharan Africa. Clinical guidelines recommending treatment thresholds are not specific to sub-Saharan African patients and are based on natural history studies from Western Pacific Asian countries. Access to standard of care treatment is available for sub-Saharan African people with chronic hepatitis B virus infection in high-income countries; however, the evidence base for these treatments was not established in this cohort and areas of uncertainty remain, particularly regarding HCC surveillance and treatment discontinuation. Participation in phase III clinical trials for chronic hepatitis B therapies is almost non-existent amongst sub-Saharan African patients, even when residing in high-income countries that participate in multicentre trials. Engagement with sub-Saharan African patients with chronic hepatitis B in high-income countries is challenging because of the stigma associated with the diagnosis, absence of routine screening systems and the complexities involved in navigating the healthcare system. Nonetheless, improved engagement is critical if we are to achieve global hepatitis B virus elimination.

Prevalence of neutropenia among adult Arabs in Qatar: Relation to other hematological parameters and anthropometric data

Neutropenia ranges from a normal variant to life-threatening acquired and congenital disorders. This study aims at providing baseline information regarding the prevalence and spectrum of neutropenia in the Arab blood donors who are living in Qatar. This retrospective cohort study was conducted to review the data of healthy Arab individuals (≥18 years) who donated blood between January 1, 2015 to May 15, 2019. A complete blood count was performed using automated analyzers. The prevalence of neutropenia was 10.7%. The prevalence in females was 32% and in males, it was 6%. Absolute neutrophil count (ANC) below 1 × 109/L was detected in 10% of Arab females and 1.8 % of Arab males. In females, the neutropenic group had significantly lower hemoglobin (Hb) levels and higher red cell distribution width, and lower total white blood cells and lymphocyte counts (P < .001) compared to the group with ANC > 1.5 × 109/L. Significant correlations were found between the ANC and Hb (r = 0.33, P < .05) and ANC and total white blood cells (r = 0.45, P < .01). The prevalence of neutropenia is considerably high in Arab adult females compared to other ethnic groups. Besides the genetic constitution of Arabs, the lower Hb and higher red cell distribution width in females suggest that iron deficiency could contribute to the development of neutropenia.

Frequency of benign neutropenia among Black versus White individuals undergoing a bone marrow assessment

Healthy individuals in the United States identified as having Black race have lower neutrophil counts, on average, than individuals identified as having White race, which could result in more negative diagnostic evaluations for neutropenia. To test this hypothesis, the proportion of evaluations where the final diagnosis was clinically insignificant neutropenia for Black and White individuals who underwent an evaluation by a haematologist that included a bone marrow (BM) biopsy to investigate neutropenia was assessed. 172 individuals without prior haematological diagnoses who underwent a haematological evaluation to investigate neutropenia. Individuals diagnosed with clinically insignificant neutropenia between Black and White individuals were compared using a propensity-score-adjusted logistic regression. Of 172 individuals, 42 (24%) were classified as Black race, 86 (50%) were males, and the 79 (46%) were over 18 years old. A BM biopsy did not identify pathology in 95% (40 of 42) of Black individuals and 68% (89 of 130) of White Individuals. Black individuals (25 of 42 [60%]) received a final diagnosis of clinically insignificant neutropenia, compared to White individuals (12 of 130 [9%]) (adjusted odds ratio =7.9, 95% CI: 3.1 - 21.1). We conclude that black individuals were more likely to receive a diagnosis of clinically insignificant neutropenia after haematological assessment.

Effects of Prophylactic Administration of Granulocyte Colony-Stimulating Factor on Peripheral Leukocyte and Neutrophil Counts Levels After Chemotherapy in Patients With Early-Stage Breast Cancer: A Retrospective Cohort Study

Background

Both chemotherapy-induced neutropenia (CIN) and febrile neutropenia (FN) frequently occur and can lead to dose-limiting toxicity and even fatal chemotherapy side effects. The prophylactic use of recombinant human granulocyte colony-stimulating factor (rhG-CSF), including pegylated rhG-CSF (PEG-rhG-CSF), significantly reduces the risks of CIN and FN during chemotherapy in early-stage breast cancer (ESBC) patients. However, whether the prophylactic use of granulocyte colony-stimulating factor (G-CSF), especially PEG-rhG-CSF, can influence white blood cell (WBC) counts and absolute neutrophil counts (ANCs) after finishing the chemotherapy remains unknown. Therefore, exploring the development and recovery tendency of WBC counts and ANCs during and after chemotherapy is crucial.

Objective

We aimed to investigate the variation tendency and recovery of WBC counts and ANCs during and after chemotherapy and evaluate the independent factors influencing leukopenia and neutropenia lasting longer after chemotherapy. We also aimed to provide individualized prophylactically leukocyte elevation therapy for breast cancer patients.

Methods

This single-center retrospective cohort study evaluated 515 ESBC patients who received rhG-CSF or PEG-G-CSF for prophylaxis after adjuvant or neoadjuvant chemotherapy. Blood test reports were analyzed during chemotherapy, and on a 12-month follow-up period after finishing the chemotherapy. The WBC counts and ANCs were measured to assess their variation tendency characteristics and to identify independent factors that influenced the occurrence of leukopenia and neutropenia lasting longer than 12 months after chemotherapy.

Results

Prophylaxis with rhG-CSF or PEG-rhG-CSF kept the mean values of WBC counts and ANCs within the normal range during chemotherapy, but a significant difference in WBC levels was detected before the end of the last chemotherapy compared to the prechemotherapy period (baseline) (p < 0.001). During the 12-month follow-up after the end of the last chemotherapy, WBC counts and ANCs gradually recovered, but the group that used only PEG-rhG-CSF (long-acting group, p _WBC = 0.012) or rhG-CSF (short-acting group, p _WBC = 0.0005) had better leukocyte elevation effects than the mixed treatment group (PEG-rhG-CSF mixed rhG-CSF). Besides, the short-acting group had a better neutrophil elevation effect than the longer-acting (p _ANC = 0.019) and mixed (p _ANC = 0.002) groups. Leukopenia was still present in 92 (17.9%) patients and neutropenia in 63 (12.2%) 12 months after the end of the last chemotherapy. The duration of leukopenia over 12 months was closely associated with the baseline WBC level (p < 0.001), G-CSF types (p = 0.027), and surgical method (p = 0.041). Moreover, the duration of neutropenia over 12 months was closely related to the baseline ANC (p < 0.001), G-CSF types (p = 0.043), and molecular typing (p = 0.025).

Conclusion

The prophylactic application of G-CSF effectively stabilized the WBC counts and ANCs during chemotherapy in ESBC patients. Nevertheless, the recovery of WBC counts and ANCs after chemotherapy varied between different G-CSF treatment groups. The risk of leukopenia and neutropenia persisting for more than 12 months after chemotherapy was associated with G-CSF types, the baseline level of WBC count/ANCs, surgical method, and molecular typing.

Ceftriaxone-Induced Reversible Agranulocytosis: A Case Report and Review of Drug-Induced Agranulocytosis

In the modern era of medicine, agranulocytosis is a rare occurrence. Despite significant improvement in patient survival, it still carries significant mortality. Agranulocytosis is most commonly caused by chemotherapeutic agents and numerous non-chemo drugs. As it can develop anytime during treatment and patients can remain asymptomatic, frequent cell count monitoring is an essential tool to make a timely diagnosis. An appropriate drug switch, work up to rule out infection and granulocyte colony-stimulating factor (G-CSF) injection in high-risk cases is the management. The patient should be kept under observation till the resolution of agranulocytosis. We present a case of ceftriaxone-induced agranulocytosis which was completely reversible upon stoppage of drug and granulocyte colony-stimulating factor administration. The pathogenesis of ceftriaxone-induced agranulocytosis is unknown. It is suggested to occur either by an immunologic mechanism or because of direct drug toxicity.

Genetic Influence on Frequencies of Myeloid-Derived Cell Subpopulations in Mouse

Differences in frequencies of blood cell subpopulations were reported to influence the course of infections, atopic and autoimmune diseases, and cancer. We have discovered a unique mouse strain B10.O20 containing extremely high frequency of myeloid-derived cells (MDC) in spleen. B10.O20 carries 3.6% of genes of the strain O20 on the C57BL/10 genetic background. It contains much higher frequency of CD11b⁺Gr1⁺ cells in spleen than both its parents. B10.O20 carries O20-derived segments on chromosomes 1, 15, 17, and 18. Their linkage with frequencies of blood cell subpopulations in spleen was tested in F₂ hybrids between B10.O20 and C57BL/10. We found 3 novel loci controlling MDC frequencies: Mydc1, 2, and 3 on chromosomes 1, 15, and 17, respectively, and a locus controlling relative spleen weight (Rsw1) that co-localizes with Mydc3 and also influences proportion of white and red pulp in spleen. Mydc1 controls numbers of CD11b⁺Gr1⁺ cells. Interaction of Mydc2 and Mydc3 regulates frequency of CD11b⁺Gr1⁺ cells and neutrophils (Gr1⁺Siglec-F^- cells from CD11b⁺ cells). Interestingly, Mydc3/Rsw1 is orthologous with human segment 6q21 that was shown previously to determine counts of white blood cells. Bioinformatics analysis of genomic sequence of the chromosomal segments bearing these loci revealed polymorphisms between O20 and C57BL/10 that change RNA stability and genes’ functions, and we examined expression of relevant genes. This identified potential candidate genes Smap1, Vps52, Tnxb, and Rab44. Definition of genetic control of MDC can help to personalize therapy of diseases influenced by these cells.

Clozapine- and non-clozapine-associated neutropenia in patients with schizophrenia: a retrospective cohort study

INTRODUCTION

The antipsychotic drug clozapine remains underutilized partly because of the risk of life-threatening adverse effects, such as neutropenia. Therefore, an extensive hematological monitoring program was set up to detect neutropenia.

METHODS

In this retrospective cohort study, we used registry-based data from the Capital Region of Denmark to investigate incidence rates of neutropenia among patients with a diagnosis of schizophrenia or other psychotic disorders and treated with clozapine for the first time. In a within-subject design, we compared rates of neutropenia in time periods where patients were exposed to clozapine versus time periods, where they were not exposed to clozapine. We also investigated whether the lengths of clozapine-associated neutropenia (CAN) were related to discontinuation of clozapine treatment.

RESULTS

Data from 520 clozapine users were included. The incidence rate of CAN was 3.2 cases per 100 person-years (95% confidence interval [CI]: 2.1-4.8) throughout the entire study. There was no significant difference in incidence rates of neutropenia during clozapine exposure and non-clozapine exposure, with an incidence rate ratio of 0.7 (95% CI: 0.4-1.3). One episode of severe neutropenia was detected. Episodes of CAN with only one sub-threshold neutrophil count were not associated with higher clozapine discontinuation (26%) than CAN episodes of more than one sub-threshold neutrophil count (28%).

CONCLUSION

In the present study, we could not confirm that clozapine treatment was associated with neutropenia.

Obesity and the Bidirectional Risk of Cancer and Cardiovascular Diseases in African Americans: Disparity vs. Ancestry

Cardiovascular disease (CVD) and cancer often occur in the same individuals, in part due to the shared risk factors such as obesity. Obesity promotes adipose inflammation, which is pathogenically linked to both cardiovascular disease and cancer. Compared with Caucasians, the prevalence of obesity is significantly higher in African Americans (AA), who exhibit more pronounced inflammation and, in turn, suffer from a higher burden of CVD and cancer-related mortality. The mechanisms that underlie this association among obesity, inflammation, and the bidirectional risk of CVD and cancer, particularly in AA, remain to be determined. Socio-economic disparities such as lack of access to healthy and affordable food may promote obesity and exacerbate hypertension and other CVD risk factors in AA. In turn, the resulting pro-inflammatory milieu contributes to the higher burden of CVD and cancer in AA. Additionally, biological factors that regulate systemic inflammation may be contributory. Mutations in atypical chemokine receptor 1 (ACKR1), otherwise known as the Duffy antigen receptor for chemokines (DARC), confer protection against malaria. Many AAs carry a mutation in the gene encoding this receptor, resulting in loss of its expression. ACKR1 functions as a decoy chemokine receptor, thus dampening chemokine receptor activation and inflammation. Published and preliminary data in humans and mice genetically deficient in ACKR1 suggest that this common gene mutation may contribute to ethnic susceptibility to obesity-related disease, CVD, and cancer. In this narrative review, we present the evidence regarding obesity-related disparities in the bidirectional risk of CVD and cancer and also discuss the potential association of gene polymorphisms in AAs with emphasis on ACKR1.

Preoperative Leukocytosis Among Female Patients Predicts Poor Postoperative Outcomes Following EVAR For Intact Infrarenal AAA

OBJECTIVES

Elevated white blood count (WBC) can be predictive of adverse outcomes following vascular interventions, but the association has not established using multi-institutional data. We evaluated the predictive value of preoperative WBC after endovascular abdominal aortic aneurysm repair (EVAR) for non-ruptured abdominal aortic aneurysms (AAA) in a nationally representative surgical database.

METHODS

Patients with non-ruptured AAA undergoing EVAR were identified in the vascular-targeted National Surgical Quality Improvement Program (NSQIP) database. Baseline characteristics were compared between patients with WBC < 10 K/μL and WBC ≥ 10 K/μL. Multivariable logistic regression analyses were performed to assess the odds of outcomes. The primary outcome was 30-day mortality. Multiple secondary outcomes including length of stay (LOS) > 1 week, 30-day readmission, lower extremity (LE) ischemia, ischemic colitis, myocardial infarction (MI) and others were assessed based on WBC and patient sex.

RESULTS

A total of 10955 patients were included with a mean WBC 7.7 ± 2.7 K/μL. Patients with WBC ≥ 10 K/μL were younger (71.8 ± 9.5 years versus 74.1 ± 8.7 years; P < .001) and were more likely to be diabetic, on steroids, smokers, functionally dependent and presenting emergently (all P ≤ .009). Aneurysm diameter was larger in WBC ≥ 10 K/μL patients (5.9 ± 1.5 cm versus 5.7 ± 1.5 cm; P < .001). Patients with WBC ≥ 10 K/μL had more mortality (2.4% vs 1.3%), LOS > 1 week (13.5% versus 6.7%), 30-day readmissions (9.8% versus 7.3%), LE ischemia (2.3% vs 1.4%), ischemic colitis (1.2% vs 0.5%), and MI (2.0% vs 1.1% ) (all P ≤ .008). Female patients with WBC ≥ 10 K/μL, compared to male patients with WBC ≥ 10 K/μL had more adverse events including mortality, LOS > 1 week, 30-day readmission, LE ischemia (all P ≤ .025). With each incremental increase in WBC by 1K/μL, the adjusted odds ratio of adverse outcomes for all patient was higher (mortality: 1.05 [95% CI, 1.00-1.10], readmission: 1.03 [95% CI, 1.00-1.06], LOS > 1 week: 1.08 [95% CI, 1.05-1.10] and ischemic colitis: 1.11 [95% CI, 1.05-1.16]; all P < .05). The effect was more pronounced in female patients and statistically significant.

CONCLUSIONS

WBC is a predictor of adverse outcomes in patients undergoing EVAR for non-ruptured AAA. After adjusting for associated risk factors, the effect of increasing WBC was more prominent for female patients. Preoperative WBC should be used as a prognostic factor to predict adverse outcomes among EVAR patients.

Neutropenia in Children Treated With Ketogenic Diet Therapy

OBJECTIVES

The objectives were to investigate the relationship between ketogenic diet therapy and neutropenia in children with epilepsy.

METHODS

A retrospective chart review of children who initiated ketogenic diet at the Hospital for Sick Children between January 1, 2000, and May 1, 2018 was performed. Factors associated with the development of neutropenia during ketogenic diet therapy were evaluated and the relationship between development of a significant or suspected infection and neutrophil count was analyzed.

RESULTS

One hundred two children met inclusion criteria and were followed on the diet for up to 24 months. Thirteen of 102 (13%) children were neutropenic at diet initiation. In the remaining 89 children, 27 developed neutropenia. Developing neutropenia was significantly associated with the ketogenic diet at 6 (13%), 12 (23%), and 24 (25%) months follow-up. Developing neutropenia was associated with higher urinary ketones (OR = 4.26, 95% CI: 1.27, 14.15) and longer duration of ketogenic diet therapy (OR = 3.29, 95% CI: 1.42, 7.96). There was no significant association between development of a clinically significant infection and neutropenia.

CONCLUSION

Ketogenic diet therapy is associated with neutropenia in children with epilepsy, however, it does not have a significant clinical impact. Concern regarding neutropenia should not discourage the use of the ketogenic diet in children.

Detectable Unmetabolized Folic Acid and Elevated Folate Concentrations in Folic Acid-Supplemented Canadian Children With Sickle Cell Disease

Sickle cell disease (SCD) is an inherited hemoglobinopathy caused by a variant (rs344) in the HBB gene encoding the β-globin subunit of hemoglobin. Chronic hemolytic anemia and increased erythropoiesis and RBC turnover in individuals with SCD can result in increased needs for folate and other B-vitamins. We assessed B-vitamin status, and the distribution of folate forms, including unmetabolized folic acid (UMFA), in Canadian children with SCD supplemented with 1 mg/d folic acid (current routine practice). Non-fasted serum and plasma samples were analyzed for concentrations of folate, and vitamins B-2, B-6, and B-12. Eleven individuals (45% male; SCD type: HbSS n = 8, HbSC n = 2, HbSβ⁰-Thal n = 1), with a median (IQR) age of 14 (7, 18) years, were included. Total folate concentrations were 3-27 times above the deficiency cut-off (10 nmol/L), and 64% of children had elevated folate levels (>45.3 nmol/L). UMFA (>0.23 nmol/L) was detected in all children, and 36% of participants had elevated levels of UMFA (>5.4 nmol/L). All children were vitamin B-12 sufficient (>150 pmol/L), and the majority (55%) had sufficient B-6 status (>30 nmol/L). Among this sample of Canadian children with SCD, there was limited evidence of B-vitamin deficiencies, but UMFA was detectable in all children.

Clozapine Metabolism is Associated With Absolute Neutrophil Count in Individuals With Treatment-Resistant Schizophrenia

Up to one-third of those with schizophrenia fail to respond to standard antipsychotics and are considered to have treatment-resistant schizophrenia, a condition for which clozapine is the only evidence-based medication. While up to 60% of treated individuals obtain therapeutic benefits from clozapine, it is currently underprescribed worldwide, partly because of concerns related to its broad adverse effect profile. In particular, the potential effects of clozapine on the immune system have gained relevance after a recent study showed that drug plasma concentrations were inversely correlated with neutrophil counts in individuals routinely undergoing treatment. Seeking to investigate this relationship in more detail, we extracted metabolic, immune, and genetic data from a UK cohort of long-term clozapine users linked to a clozapine monitoring service, CLOZUK2 (N = 208). Whilst a correlation analysis was compatible with the original results, a multiple linear regression accounting for dose and other confounding factors additionally allowed us to estimate the decrease in absolute neutrophil counts to approximately 141 cells/mm3 for every 0.1 mg/L increase in clozapine concentration. However, this association was attenuated after controlling for the metabolic ratio between clozapine and its main metabolite, norclozapine, which was itself negatively associated with neutrophil concentrations. Further analyses revealed that these relationships are likely moderated by genetic factors, as three pharmacogenomic SNPs previously associated to norclozapine plasma concentrations and the metabolic ratio (rs61750900, rs2011425 and rs1126545) were shown to be independently associated with a variation in neutrophil counts of about 400 cells/mm3 per effect allele. Such results are compatible with an effect of norclozapine, but not necessarily clozapine, on immune cell counts, and highlight the need for further investigations into the potential role of genetic determinants of clozapine pharmacokinetics in the occurrence of adverse effects during treatment.

When non-Whiteness becomes a condition

The term "benign ethnic neutropenia" describes the phenotype of having an absolute neutrophil count (ANC) <1500 cells/μL with no increased risk of infection. It is most commonly seen in those of African ancestry. In addition, ANC reference ranges from countries in Africa emphasize that ANC levels <1500 cells/μL are common and harmless. The lower ANC levels are driven by the Duffy null [Fy(a-b-)] phenotype, which is protective against malaria and seen in 80% to 100% of those of sub-Saharan African ancestry and <1% of those of European descent. Benign ethnic neutropenia is clinically insignificant, but the average ANC values differ from what are typically seen in those of European descent. Thus, the predominantly White American medical system has described this as a condition. This labeling implicitly indicates that common phenotypes in non-White populations are abnormal or wrong. We believe that it is important to examine and rectify practices in hematology that contribute to systemic racism.

HLA-DQB1 6672G>C (rs113332494) is associated with clozapine-induced neutropenia and agranulocytosis in individuals of European ancestry

The atypical antipsychotic clozapine is the only effective medication for treatment-resistant schizophrenia. However, it can also induce serious adverse drug reactions, including agranulocytosis and neutropenia. The mechanism by which it does so is largely unknown, but there is evidence for contributing genetic factors. Several studies identified HLA-DQB1 variants and especially a polymorphism located in HLA-DQB1 (6672G>C, rs113332494) as associated with clozapine-induced agranulocytosis and neutropenia. We analysed the risk allele distribution of SNP rs113332494 in a sample of 1396 controls and 178 neutropenia cases of which 60 developed agranulocytosis. Absolute neutrophil counts of 500/mm³ and 1500/mm³ were used for defining agranulocytosis and neutropenia cases, respectively. We also performed association analyses and analysed local ancestry patterns in individuals of European ancestry, seeking replication and extension of earlier findings. HLA-DQB1 (6672G>C, rs113332494) was associated with neutropenia (OR = 6.20, P = 2.20E-06) and agranulocytosis (OR = 10.49, P = 1.83E-06) in individuals of European ancestry. The association signal strengthened after including local ancestry estimates (neutropenia: OR = 10.38, P = 6.05E-08; agranulocytosis: OR = 16.31, P = 1.39E-06), with effect sizes being considerably larger for agranulocytosis. Using local ancestry estimates for prediction, the sensitivity of rs113332494 increased from 11.28 to 55.64% for neutropenia and from 16.67 to 53.70% for agranulocytosis. Our study further strengthens the evidence implicating HLA-DQB1 in agranulocytosis and neutropenia, suggesting components of the immune system as contributing to this serious adverse drug reaction. Using local ancestry estimates might help in identifying risk variants and improve prediction of haematological adverse effects.

Dynamics of leucocyte DNA thioguanine nucleotide levels during maintenance therapy of childhood acute lymphoblastic leukemia

PURPOSE

Methotrexate (MTX)/6-Mercaptopurine (6MP)-based maintenance therapy is crucial to cure childhood acute lymphoblastic leukemia (ALL). Cytotoxicity is mediated by incorporation of thioguanine nucleotides (TGN) into DNA (DNA-TG) with higher levels in leucocytes being associated with reduced relapse risk. To further understand the dynamics of DNA-TG formation, we measured DNA-TG levels in leucocyte subsets during maintenance therapy and in the months following its discontinuation.

METHODS

DNA-TG levels were measured in leucocytes (DNA-TG_Total), polymorph nucleated granulocytes (neutrophils, eosinophils, basophils [DNA-TG_PMN]) and mononucleated cells (lymphocytes, monocytes [DNA-TG_MNC]) in 1013 samples from 52 patients on ALL maintenance therapy (951 samples during therapy and 62 samples after therapy discontinuation, respectively).

RESULTS

Median DNA-TG_Total, DNA-TG_PMN and DNA-TG_MNC during maintenance therapy were 539, 563 and 384 fmol/µg DNA, respectively. DNA-TG_PMN displayed more pronounced fluctuation than DNA-TG_MNC (range 0-3084 [interquartile range IQR 271-881] versus 30-1411 [IQR 270-509] fmol/µg DNA). DNA-TG_Total was more strongly correlated with DNA-TG_PMN (r_S = 0.95, p < 0.0001) than DNA-TG_MNC (r_S = 0.73, p < 0.0001). DNA-TG_PMN correlated less with DNA-TG_MNC (r_S = 0.64, p < 0.0001) and to a much lesser extent with absolute neutrophil count (r_S = 0.35, p < 0.0001). Following discontinuation of therapy, DNA-TG_PMN was rapidly eliminated, and not measurable beyond day 22 after discontinuation, whereas DNA-TG_MNC was slowly eliminated, and five patients demonstrated a measurable DNA-TG_MNC more than 365 days after therapy discontinuation.

CONCLUSION

Fluctuations in DNA-TG_Total are predominantly caused by corresponding fluctuations in DNA-TG_PMN, thus DNA-TG_Total measures recent TGN incorporation in these short-lived cells. Measurement of DNA-TG_Total at 2-4 weeks intervals provides a reliable profile of DNA-TG levels.

Students' perceptions on race in medical education and healthcare

Major racial disparities continue to exist in our healthcare education, from the underrepresentation of ethnic minorities when teaching about clinical signs to health management in primary and secondary care. A multi-centre group of students discuss what needs to change in medical education to cultivate physicians who are better prepared to care for patients of all backgrounds. We argue that the accurate portrayal of race in medical education is a vital step towards educating medical students to consider alternative explanations to biology when considering health inequities.

Benign ethnic neutropenia in a South African population, and its association with HIV acquisition and adverse event reporting in an HIV vaccine clinical trial

Benign ethnic neutropenia (BEN) is defined as a neutrophil count of <1.5×10⁹ cells/L in healthy individuals and is more common in populations of certain ethnicities, e.g. African or Middle Eastern ethnicity. Neutrophil values are commonly included in eligibility criteria for research participation, but little is known about the relationship between BEN, HIV acquisition, and the occurrence of adverse events during clinical trials. We investigated these relationships using data from an HIV vaccine efficacy trial of healthy adults from 5 South African sites. We analysed data from the double-blind, placebo-controlled, randomized trial HVTN 503, and its follow-on study HVTN 503-S to assess the prevalence of BEN, its association with HIV infection, and adverse event reporting. These data were then compared with a time- and age-matched, non-pregnant cohort from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007–2008 in the United States (US). The 739 South African participants had a median age of 22.0 years (interquartile range = 20–26) and 56% (n = 412) were male. Amongst the US cohort of 845 participants, the median age was 26 (IQR: 21–30) and the majority (54%, 457/745) were also male. BEN was present at enrolment in 7.0% (n = 52) of South African participants (6% in the placebo group versus 8% in the vaccine group); 81% (n = 42) of those with BEN were male. Pretoria North had the highest prevalence of BEN (11.6%, 5/43), while Cape Town had the lowest (0.7%, 1/152). Participants with BEN had a lower median neutrophil count (1.3 vs. 3.2x10⁹ cells/L; p<0.001) and BMI (20.8 vs. 22.3 kg/m²; p<0.001) when compared to those without BEN. A greater proportion of Black South Africans had neutrophil counts <1.5×10⁹ cells/L compared to US non-Hispanic Whites from the NHANES cohort (7% [52/739] vs. 0.6% [3/540]; p<0.001). BEN did not increase the odds for HIV infection (adjusted odds ratio [aOR]: 1.364, 95% confidence interval [95% CI]: 0.625–2.976; p = 0.4351). However, female gender (aOR: 1.947, 95% CI: 1.265–2.996; p = 0.0025) and cannabis use (aOR: 2.192, 95% CI: 1.126–4.266; p = 0.0209) increased the odds of HIV acquisition. The incidence rates of adverse events were similar between participants in the placebo group with BEN, and those without: 12.1 (95% CI: 7.3–20.1) vs. 16.5 (95% CI: 14.6–18.7; p = 0.06) events per 100 person-years (py) were noted in the infections and infestations system organ class, respectively. The vaccine group had an event incidence rate of 19.7 (95% CI: 13.3–29.2) vs. 14.8 (95% CI: 13.0–16.8; p = 0.07) events per 100py in the group with, and without BEN, respectively. BEN is more prevalent in Black South Africans compared to US Non-Hispanic Whites. Our data do not support excluding populations from HIV vaccine trials because of BEN. BEN was not associated with increased risk for HIV infection or Adverse events on a vaccine trial. Predictors of HIV infection risk were females and cannabis use, underlying the continued importance of prevention programmes in focusing on these populations.

Hot topics in coagulation testing: Important considerations for testing children for bleeding/thrombotic disorders

The accurate use and interpretation of diagnostic investigations are essential for safe and effective patient care. Appropriate application and interpretation of coagulation testing can be challenging, and many controversies exist relating to the standardization of testing procedures, the application of relevant tests to different patient populations and the interpretation of test results. We present a list of the most prominent controversies in coagulation testing and have selected three specific examples (age-appropriate reference ranges, therapeutic anticoagulation monitoring and tests of thrombin generation) for closer discussion, highlighting examples with a paediatric framework. We discuss the limitations of discrete age-partitioned reference intervals, given the established principle of developmental haemostasis; the difficulties in establishing normative data across different laboratories; important pre-analytical variables affecting coagulation testing; the challenges in interpreting APTT and anti-Xa assays for monitoring unfractionated heparin therapy in different clinical situations; and the limitations in interpreting tests of thrombin generation due to current available thrombin-specific substrates and the complicating factor of variable alpha2-macroglobulin levels. These controversies are demonstrated using paediatric examples, but raise important implications for coagulation testing in patients of all ages and highlight the pressing need for further research in these areas.

How I investigate neutropenia

Neutropenia is a common laboratory finding in adults and children. Its underlying causes are extremely heterogeneous and include benign conditions, autoimmune disorders, infections, and malignancies. The clinical laboratory plays a central role in the diagnosis of these disorders, including data derived from hematology, microbiology, molecular biology/cytogenetics, and clinical chemistry. The purpose of this review is to (a) highlight the clinical, hematologic, and molecular genetic features of the major entities resulting in neutropenia and (b) outline an algorithm-based approach to permit the classification of neutropenias.

The Duffy-null genotype and risk of infection

Many medical treatments, from oncology to psychiatry, can lower white blood cell counts and thus access to these treatments can be restricted to individuals with normal levels of white blood cells, principally in order to minimize risk of serious infection. This adversely affects individuals of African or Middle Eastern ancestries who have on average a reduced number of circulating white blood cells, because of the Duffy-null (CC) genotype at rs2814778 in the ACKR1 gene. Here, we investigate whether the Duffy-null genotype is associated with the risk of infection using the UK Biobank sample and the iPSYCH Danish case-cohort study, two population-based samples from different countries and age ranges. We found that a high proportion of those with the Duffy-null genotype (21%) had a neutrophil count below the threshold often used as a cut-off for access to relevant treatments, compared with 1% of those with the TC/TT genotype. In addition we found that despite its strong association with lower average neutrophil counts, the Duffy-null genotype was not associated with an increased risk of infection, viral or bacterial. These results have widespread implications for the clinical treatment of individuals of African ancestry and indicate that neutrophil thresholds to access treatments could be lowered in individuals with the Duffy-null genotype without an increased risk of infection.

ASHP Therapeutic Position Statement on the Use of Antipsychotic Medications in the Treatment of Adults with Schizophrenia and Schizoaffective Disorder

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

Awan Z, Abouzaid AA, Elbahaie HM, Al Amoudi SM, Andarawi M, F Shehata S. The Prevalence of Isolated Neutropenia at High Altitude in Southern Saudi Arabia: Does Altitude Affect Leucocyte Count?

INTRODUCTION

Isolated neutropenia is a common problem in hematology practice. Benign ethnic neutropenia (BEN) is the common form of neutropenia worldwide and it affects mainly African and Middle Eastern ethnicities. Most cases of isolated mild and moderate neutropenia are benign and associated with no clinical significance. The aim of this study was to estimate the prevalence of isolated neutropenia at high-altitude southern Saudi Arabia.

METHODS

A large dataset of complete blood counts (CBCs) was analyzed for walk-in patients of both genders, of age ranges from 12 to 60 years doing blood tests at a commercial lab for high altitude - 2,270 meters above sea level - (HA) group, and from sea level SL group. Abnormal biochemical or CBC results were excluded before analysis.

RESULTS

For HA group, 3123 CBCs were analyzed and for SL group 18,427 CBCs were analyzed. The prevalence of mild neutropenia, defined as absolute neutrophil count (ANC) in the range of 1.0-.5× 109/L, was 12.4% (n=399) versus 5.6% (n=1025), while moderate neutropenia, defined as ANC of 0.5-1 × 109/L, was present 6% (n=191) versus 1.45% (n=269) in the high altitude and sea level groups, respectively. Severe neutropenia, defined as neutrophil count less than 0.5-1 × 109/L, was rare in both groups.

CONCLUSION

Isolated neutropenia is common in Saudis living at high altitude. While benign ethnic neutropenia (BEN) is thought to be the major contributing factor to this high prevalence, other factors including environmental factors and altitude are possible contributing factors along with underlying ethnic neutropenia.

Systematic review of racial disparities in clozapine prescribing

OBJECTIVE

To conduct a systematic review of published evidence on clozapine prescribing disparities across racial and ethnic categories, estimate the size of these disparities, and assess possible causes to inform future monitoring and intervention.

METHODS

Electronic databases (MEDLINE, Embase, PsycINFO, Web of Science) were searched for directly relevant studies. Three independent reviewers selected studies: (1) of US samples; (2) directly addressed ethnic and/or racial disparities in prescribing of antipsychotic medications; (3) identified specific ethnic and/or racial groups (e.g. White, Blacks, Hispanics, non-Hispanic etc.); (4) reported clozapine prescription rates and (5) reported relevant covariates (i.e. gender, age, co-morbidities etc.).

FINDINGS

16 studies met our eligibility criteria. All studies reported clozapine underutilization in ethnic and racial minority patients when compared to their white counterparts. These findings remained consistent despite different time periods, designs, data set types, and after controlling for relevant covariates such as: length of hospital stay, institutional setting, and disease severity.

CONCLUSION

The reasons for underutilization of clozapine in minority patients remain unclear. Various contributors can be categorized as: clinician-related factors (e.g. prescriber lack of experience), patient-related factors (e.g. distrust or suspicion of clinician), and institution-related factors (e.g. state operated facilities). Direct examination of these factors can help inform efforts to reduce clozapine prescription disparities.

Avoiding Peg-Filgrastim Prophylaxis During the Paclitaxel Portion of the Dose-Dense Doxorubicin-Cyclophosphamide and Paclitaxel Regimen: A Prospective Study

PURPOSE

The use of growth factors adds considerable expense and some toxicity to adjuvant breast cancer chemotherapy. We tested the feasibility and safety of omitting routine peg-filgrastim use during the paclitaxel portion of the dose-dense doxorubicin-cyclophosphamide-paclitaxel regimen.

PATIENTS AND METHODS

This was a prospective, single-arm study in which patients 18 to 65 years of age who completed 4 cycles of dose-dense doxorubicin-cyclophosphamide for stage I-III breast cancer received paclitaxel 175 mg/m² every 2 weeks. Peg-filgrastim was administered after paclitaxel only if patients had had febrile neutropenia in a prior cycle or at investigator discretion if patients had infections or treatment delays of > 1 week. Once a patient received peg-filgrastim, it was administered in all future cycles. The primary end point was the rate of paclitaxel completion within 7 weeks from cycle 1 day 1 to cycle 4 day 1. If ≥ 100 out of 125 patients completed 4 cycles of paclitaxel without dose delay, the regimen would be considered feasible.

RESULTS

The enrollment goal of 125 patients was met. Median age was 46 years (range, 21-65 years), and 112 patients (90% [95% CI, 83% to 94%]) completed dose-dense paclitaxel within 7 weeks. Omission of peg-filgrastim was not causally related to noncompletion of paclitaxel in any patients. The most common reasons for dose reduction or delays were nonhematologic. One patient experienced febrile neutropenia but was able to complete paclitaxel on time. Eight patients (6.4%) received peg-filgrastim during the trial. Overall, peg-filgrastim was administered in only 4.3% of paclitaxel cycles.

CONCLUSION

Omission of routine peg-filgrastim during dose-dense paclitaxel according to a prespecified algorithm seems to be safe and feasible and was associated with a 95.7% reduction in the use of peg-filgrastim relative to the current standard of care.

Time- and Race-Specific Haematological Reference Intervals for Healthy Volunteer Trials: A Retrospective Analysis of Pooled Data From Multiple Phase I Trials

Most UK hospitals, laboratories, and research institutions use uniform reference intervals (RI) that do not take into account known diurnal and racial variation in total white blood cells (WBC) count and its constituent parameters. These risks of excluding potentially suitable ethnic minority volunteers from participating in phase I clinical trials could call into question the validity of a trial’s findings or limit its scientific applications and ability to accurately observe drug effects upon WBC parameters. This study pools data from multiple phase I trials, assesses the effects of race and time of day on WBC count, and compares it to the existing literature to establish race and time-specific RIs. A total 13,332 venous blood samples obtained from 7,157 healthy male and female volunteers at the time of screening or admission (predosing) who took part in 35 phase I trials over a period of seven years were pooled and the data were analyzed using generalised estimating equation models. Adjusted RI of total WBC count and its individual parameters were then calculated according to time of day (morning vs. evening) for both black and nonblack populations. This study indicates that black individuals on average had lower total WBC, neutrophil, monocyte, eosinophil, and basophil counts than individuals from nonblack racial groups. Black volunteers had higher mean lymphocyte counts relative to their nonblack counterparts. These differences were deemed statistically significant. Statistically significant increases in total WBC, neutrophil, lymphocyte, and monocyte counts were also observed over the course of daily sampling. Eosinophil counts decreased during this time period, but this finding was only statistically significant in the nonblack population. Despite an observed mild diurnal increase in basophil count in both populations, this was not considered statistically significant. This high-powered study adds significant weight to the known evidence for diurnal and racial variation in WBC parameters. Importantly, it proposes specific RIs that more precisely reflect race and time of day. These could ensure increased participation of black volunteers in clinical trials for improved population representation. Furthermore, the proposed RIs allow for more accurate postdose safety monitoring and reporting, and ensure improved monitoring of postdose WBC count changes.

Prediction of leukocyte counts during paediatric acute lymphoblastic leukaemia maintenance therapy

Maintenance chemotherapy with oral 6-mercaptopurine and methotrexate remains a cornerstone of modern therapy for acute lymphoblastic leukaemia. The dosage and intensity of therapy are based on surrogate markers such as peripheral blood leukocyte and neutrophil counts. Dosage based leukocyte count predictions could provide support for dosage decisions clinicians face trying to find and maintain an appropriate dosage for the individual patient. We present two Bayesian nonlinear state space models for predicting patient leukocyte counts during the maintenance therapy. The models simplify some aspects of previously proposed models but allow for some extra flexibility. Our second model is an extension which accounts for extra variation in the leukocyte count due to a treatment adversity, infections, using C-reactive protein as a surrogate. The predictive performances of our models are compared against a model from the literature using time series cross-validation with patient data. In our experiments, our simplified models appear more robust and deliver competitive results with the model from the literature.

Normalcy, Race, and Biomedical Technology in Brazil: The Case of Low White Blood Cell Count

This article explores the intersection between low-complexity biomedical technologies and ideas about race in Brazil. Using ethnographic material collected in the northeastern city of Salvador on the clinical management of low white blood cell count (leukopenia), and debates involving doctors, biomedical scientists, and social movement activists on establishing racialized parameters in complete blood count tests, I explore how the notion of normalcy is connected to ideas about racial difference. Taken both at a population and individual bodily level, normalcy serves to contrast local history, portrayed as the result of widespread admixture between groups, with other national contexts, such as that of the United States. While a material body that cannot be classified as racially pure is seen as normal in the contemporary Brazilian context, nevertheless these pure racial types feature discursively as existing in a long lost past of Brazil's history. At the same time, normalcy can also be locally challenged by certain actors, such as social movement activists, who underline the specific experience of certain racialized bodies, questioning the overarching national narratives of admixture and arguing for the need to recognize these bodies as normal as well, particularly in the context of political struggle for the reduction of social inequalities. These two ways in which normalcy appears articulated with local meanings of race gives way to seemingly contradictory and confronting discourses. Thus, racial categories that are explicitly not identified with admixture are seen as a thing of the past (the history of the Nation) and a thing of the future (a more racially equal country). This can be better comprehended by the process through which different historical discourses on racial difference in Brazil appear in connection with, or as a proxy for, ideas such as nation, population or gender, originating from different places and moments in history.

Time to viral rebound and safety after antiretroviral treatment interruption in postpartum women compared with men

OBJECTIVE(S)

The short-term safety of treatment interruptions, a necessary part of cure studies, is not well established, particularly in women. We explored viral rebound kinetics and safety in a group of postpartum women discontinuing ART and compared results to men in historical interruption trials.

DESIGN

Prospective evaluation of time to virologic rebound.

METHODS

One thousand and seventy-six asymptomatic, virally suppressed, postpartum women living with HIV enrolled in the PROMISE trial with baseline CD4 cell counts at least 350 cells/μl underwent antiretroviral treatment (ART) discontinuation. Proportion with virologic suppression at weeks 4 and 12 were compared with participants in ACTG treatment interruption trials (91% male population).

RESULTS

In PROMISE, using interval censored methods, the estimated median time to HIV viral rebound was 2 weeks. An estimated 6% of women would remain virally suppressed at 30 weeks. Of those who had viral rebound by 30 weeks (N = 993), less than 4% experienced grade 3 or higher laboratory events, and 1% experienced WHO stage 2 or higher clinical events. Overall, less than 1% of participants progressed from WHO Stage 1 to Stage 2 or higher after discontinuation of ART, and 3.9% experienced a decline in CD4 cell count to less than 350 cells/μl or local treatment guidelines. A significantly higher proportion of women in PROMISE (25.4%) were virologically suppressed (<400 copies/ml) at 12 weeks compared with ACTG NWCS 371 participants (6.4%).

CONCLUSION

Temporary treatment interruptions in healthy, HIV-infected women with high CD4 cell counts can be well tolerated. Potential sex differences need to be considered in cure studies examining time to virologic rebound.

Comparing Ethnicity-Specific Reference Intervals for Clinical Laboratory Tests from EHR Data

BACKGROUND

The results of clinical laboratory tests are an essential component of medical decision-making. To guide interpretation, test results are returned with reference intervals defined by the range in which the central 95% of values occur in healthy individuals. Clinical laboratories often set their own reference intervals to accommodate variation in local population and instrumentation. For some tests, reference intervals change as a function of sex, age, and self-identified race and ethnicity.

METHODS

In this work, we develop a novel approach, which leverages electronic health record data, to identify healthy individuals and tests for differences in laboratory test values between populations.

RESULTS

We found that the distributions of >50% of laboratory tests with currently fixed reference intervals differ among self-identified racial and ethnic groups (SIREs) in healthy individuals.

CONCLUSIONS

Our results confirm the known SIRE-specific differences in creatinine and suggest that more research needs to be done to determine the clinical implications of using one-size-fits-all reference intervals for other tests with SIRE-specific distributions.

Benign ethnic neutropenia

Benign ethnic neutropenia (BEN) is one of the most common causes of chronic neutropenia seen in individuals of African, Middle Eastern and West Indian descent, affecting many individuals worldwide. Despite its prevalence, many physicians are not familiar with this benign condition, resulting in unnecessary evaluation and testing for neutropenia in otherwise healthy individuals. Clinically, patients with BEN are at no increased risk of infection despite their neutropenia. Implications of this condition are highlighted in those patients receiving therapies that have a known side effect of neutropenia, most commonly chemotherapy agents. Studies have suggested that disparities in survival among those patients receiving chemotherapy between patients of European decent and African decent may be attributed to measured neutropenia in these populations, questioning whether BEN could be an influential factor. This review encompasses all aspects of benign ethnic neutropenia, providing information about this condition and helping to guide clinical decision-making as to when an aggressive work up and referral are indicated and when it is appropriate to monitor. Additionally, we review the role of genetic studies in identifying the genes related to BEN, summarize the theories that offer the most accepted mechanisms behind the condition, and address the importance of pursuing larger studies to assess the implication of BEN in oncology patients as well as patients taking neutropenia-causing medications.