Clinical, laboratory, and genetic risk factors for thrombosis in sickle cell disease

The enigma of sickle cell hepatopathy: Pathophysiology, clinical manifestations and therapy

Sickle cell disease (SCD) is one of the most common genetic disorders in the world predominantly affecting economically disadvantaged populations. There is a notable discrepancy between the growing adult SCD population and available diagnostic and therapeutic interventions for SCD. Sickle cell hepatopathy (SCH) is an all-inclusive term to describe the acute and chronic liver manifestations of SCD. The pathophysiology of SCH follows no defined pattern or sequence that poses challenges to clinicians and researchers alike. Evidence is lacking for this underreported disease at various levels from diagnostic to therapeutic options. This paper reviews the basic pathophysiology, clinical features, biochemical and radiological findings of various SCH manifestations and outlines the management of each condition. Old and new therapy options in SCD including hydroxyurea, red blood cell exchange transfusion, ursodeoxycholic acid, voxelotor, l-glutamine and crizanlizumab have been reviewed to investigate the role of these options in treating SCH. The role of liver transplant, haematopoietic stem cell transplant and gene therapy in SCH patients have been reviewed.

Asymptomatic Acute Cerebral Infarction in a Patient with Hemoglobin Köln

Congenital hemoglobin disorders typically present as hemolytic anemia, but there are also numerous reports of thrombotic complications in these diseases, suggesting an associated hypercoagulative state. In hemoglobin Köln, the most common type of unstable hemoglobinopathy worldwide, there have not been many reports of such thrombotic phenomena. We herein describe the case of a patient with hemoglobin Köln demonstrating acute cerebral infarction. His father, who also had hemolytic anemia, presumably hemoglobin Köln, had a history of cerebral infarction. This case suggests that hemoglobin Köln, among other congenital hemoglobin disorders, may be a precipitating factor of thrombotic events.

Hospital acquired venous thromboembolism in children with sickle cell disease

Sickle cell disease (SCD) is well recognized as a hypercoagulablestate, however, it remains unclear whether a subgroup of children with SCD at higher risk of venous thromboembolic event (VTE) during hospitalization may benefit from thromboprophylaxis. Our objectives were to describe the clinical characteristics, outcomes and recurrence of hospital acquired VTE in patients with SCD younger than 21 years. This was a single center retrospective study. Data regarding demographics, reason for admission, location of VTE, risk factors like central venous catheter (CVC), intensive care unit (ICU) admission among others were extracted from electronic medical records over a 10-year study period (2011-2021). Recurrence of VTE at 1 and 5 years was assessed. Descriptive statistics were used as indicated. We identified a total of 20 VTE events over the 10-year study period. Six of these events occurred in those younger than 12 years of age. Fourteen (70%) VTE events occurred in the HbSS or HbSβThal0 genotypes compared to 6 (30%) in HbSC. Most common VTE was isolated pulmonary embolism (PE) (n = 10, 50%). VTE were most often associated with acute chest syndrome (ACS) (n = 14, 70%), ICU admissions (n = 10, 50%) and CVC (n = 5/9, 55%). One patient died from the VTE event. One patient with additional underlying risk factors had a recurrent VTE at 13 months. Our study suggests that ICU admission, ACS and presence of CVC increases the risk of VTE in children and young adults with SCD, but larger studies are indicated to validate our findings.

Neutrophils in sickle cell disease: Exploring their potential role as a therapeutic target

Factors influencing the activation of neutrophils in SCD and the potential neutrophil-mediated ameliorating effects of therapies in SCD.

Evaluating thromboprophylaxis in the sickle cell disease population: Navigating the evidence gap

Sickle cell disease (SCD) arises from beta-globin gene mutations, with global estimates indicating around 500 000 affected neonates in 2021. In the United States, it is considered rare, impacting fewer than 200 000 individuals. The key pathogenic flaw lies in mutant haemoglobin S, prone to polymerization under low oxygen conditions, causing erythrocytes to adopt a sickled shape. This leads to complications like vascular occlusion, haemolytic anaemia, inflammation and organ damage. Beyond erythrocyte abnormalities however, there is a body of literature highlighting the hypercoagulable state that is likely a contributor to many of the complications we see in SCD. The persistent activation of the coagulation cascade results in thromboembolic events, notably venous thromboembolism (VTE) which is independently associated with increased mortality in both adults and children with SCD. While the increased risk of VTE in the SCD population seems well established, there is a lack of guidelines for thromboprophylaxis in this population. This Wider Perspective will describe the hypercoagulable state and increased thrombosis risk in the SCD population, as well as advocate for the development of evidence-based guidelines to aid in the prevention of VTE in SCD.

Assessment of menstrual health in adolescent and young adults with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is associated with hypercoagulability, but adults with SCD also have an increased incidence of bleeding including heavy menstrual bleeding (HMB). HMB is common among adolescent females, but the impact of HMB in pediatric SCD is unclear. The objectives of this study were to examine menstrual health status, knowledge, and quality of life (QOL).

METHODS

We performed a single-institutional multi-clinic cross-sectional study comprised of a five-part survey in pediatric participants with SCD. The survey included the validated Menstrual Bleeding Questionnaire (MBQ) and Self-administered Bleeding Assessment Tool (Self-BAT).

RESULTS

Forty-eight participants with a median age of 16 years (range: 12-21 years) completed the study. The mean age at onset of menarche was 13 ± 1.3 years. On the MBQ, 29% reported heavy/very heavy menstrual flow, 61% reported moderate or severe dysmenorrhea, and 96% had menses lasting less than 1 week. The Self-BAT revealed that 42% of participants reported a history of HMB. Participants with severe dysmenorrhea or HMB had higher MBQ scores, corresponding to worse QOL. Despite this, less than 20% of participants had attempted any hormonal therapy for menstrual regulation. The odds of hormonal therapy utilization were comparable among participants on hydroxyurea versus not on hydroxyurea (odds ratio 1.58, 95% confidence interval [CI]: 0.33-7.56).

CONCLUSIONS

The prevalence of HMB and dysmenorrhea is high among adolescents and young women with SCD. Strategies that incorporate menstrual health assessment into routine medical care in this population would help address this important area of pediatric health.

A-296G variant of THBS1 gene (rs1478605) is associated with a lower frequency of stroke in a Brazilian population with sickle cell anemia

OBJECTIVES

Stroke is a devastating clinical outcome that significantly contributes to the morbidity and mortality of sickle cell anemia (SCA) patients. Despite its advantages in predicting stroke risk, transcranial Doppler screening has limitations that restrict its applicability, highlighting the need for emerging prognostic tools. Thrombospondin-1 plays a crucial role in endothelial injury, platelet adhesion, and nitric oxide metabolism and may be implicated in stroke pathophysiology. Here, we aimed to evaluate the association of THBS1 genetic variations with the occurrence of stroke in SCA patients MATERIALS AND METHODS: By real-time PCR, 512 SCA patients were fully genotyped for THBS1 A-296G (rs1478605) polymorphism RESULTS: THBS1 GG genotype was associated with a lower risk for stroke occurrence [odds ratio (OR): 0.30; 95% confidence interval (CI): 0.11-0.78; P = 0.011], although these findings were not consistent with multivariate logistic regression analysis (OR: 0.73, 95% CI: 0.12 - 4.37; P = 0.736). In agreement, the cumulative incidence of stroke for patients with AG/AA genotypes was higher when compared to the GG genotype (P = 0.018). However, the association was not maintained in the multivariate proportional hazards model (hazard ratio: 0.67, 95% CI: 0.12-3.61; P = 0.643) CONCLUSIONS: In summary, the present study shows that the THBS1 A-296G (rs1478605) polymorphism may be a potential modifier for stroke in SCA.

A comprehensive view of pregnancy in patients with sickle cell disease in high-income countries: the need for robust data and further decline in morbidity and mortality

Sickle cell disease is a major public health concern due to its prevalence and associated morbidities. In high-income countries, diagnosis and treatment advancements have extended patient's lives and enabled women to embrace motherhood. Although the provision of care in specialist centres has reduced maternal-fetal complication rates, the mortality rate among pregnant women with sickle cell disease remains disproportionately high. Complications arise from vaso-occlusive events, worsening organ damage, thrombotic risks, infections, and pregnancy-related issues, such as pre-eclampsia, premature birth, small-for-gestational-age, and pregnancy loss. Effective management during pregnancy includes preconception planning, genetic counselling, education, and collaborative care. There is no consensus on the overall approach to managing pregnant women with sickle cell disease; however, fostering a collaborative relationship between health-care professionals and researchers is crucial for advancing the understanding and management of this illness. The disparities in health-care outcomes associated with ethnicity and economic insecurity affect patients with sickle cell disease but have not been examined extensively. Hence, health-care personnel need sufficient training to address these issues alongside broader societal efforts to confront racism and discrimination. Comprehensive national and global action plans are required to address the multifaceted challenges of sickle cell disease.

Venous thromboembolism prophylaxis practices for patients with sickle cell disease prior to and during the COVID-19 pandemic

Patients with sickle cell disease (SCD) are predisposed to a hypercoagulable state due to alterations in the coagulation system. Despite concern for the development of venous thromboembolism (VTE) in this population, there are no standardized guidelines for routine thromboprophylaxis. The objective of this study was to assess thromboprophylaxis practices of adult and pediatric treaters of SCD before and during the coronavirus disease of 2019 (COVID-19) pandemic. A cross-sectional electronic survey was distributed to pediatric and adult hematology oncology practitioners through seven SCD-specific interest groups between May 29, 2020, and July 13, 2020. Of 93 total responses, 14% ( N  = 13) reported they only treat patients more than 21 years old; 38.7% ( N  = 36) only treat patients 0-21 years old and 47.3% ( N  = 44) reported they treat both. Our study showed that before the COVID-19 pandemic, 96% of adult practitioners would recommend pharmacologic thromboprophylaxis, mechanical thromboprophylaxis or both for hospitalized adults with thromboprophylaxis, but only 76% of pediatric treaters would recommend any thromboprophylaxis in hospitalized children ( P  < 0.0001), with 24% of pediatric treaters choosing no thromboprophylaxis at all. During the COVID-19 pandemic, pharmacologic thromboprophylaxis specifically was recommended for adults by 94% of treaters and for pediatric patients by 76% of treaters. These findings suggest that despite the lack of evidence-based thromboprophylaxis guidelines in adults and children with thromboprophylaxis, subspecialty treaters routinely provide pharmacologic thromboprophylaxis in their adult patients and will modify their practice in pediatric patients who are considered at a high risk for VTE.

Pregnancy-related thromboembolism in women with sickle cell disease: An analysis of National Medicaid Data

Pregnancy and sickle cell disease (SCD) both individually carry a risk of thromboembolism (TE). Pregnancy in people with SCD may further enhance the prothrombotic effect of the underlying disease. The objectives of this study were to determine the rate and risk factors for arterial and venous thrombosis in pregnant people with SCD. Administrative claims data from the United States Centers for Medicare and Medicaid Service Analytic eXtract from 2006 to 2018 were used. The study population included people with SCD from the start of their first identified pregnancy until 1 year postpartum and a control cohort of pregnant people without SCD of similar age and race. Outcomes of interest were identified with ICD-9 or 10 codes. Logistic regression analyses were used to analyze risk factors. We identified infant deliveries in 6388 unique people with SCD and 17 110 controls. A total of 720 venous thromboembolism (11.3%) and 335 arterial TE (5.2%) were observed in people with SCD compared to 202 (1.2%) and 95 (0.6%) in controls. People with SCD had an 8-11 times higher odds of TE compared to controls (p < .001). Within the SCD cohort, age, hemoglobin SS (HbSS) genotype, hypertension, and history of thrombosis were identified as independent risk factors for pregnancy-related TE. Pregnancy-specific factors (pre-eclampsia, eclampsia, multigestational pregnancy) were not associated with TE. In conclusion, the risk of pregnancy-related TE is considerably higher in people with SCD compared with controls without SCD. Hence, people with SCD, particularly those with multiple risk factors may be candidates for thromboprophylaxis during pregnancy and the postpartum period.

Predisposing Factors and Incidence of Venous Thromboembolism among Hospitalized Patients with Sickle Cell Disease

Though patients with sickle cell disease (SCD) are at risk of developing venous thromboembolism (VTE), clear estimates of its incidence and predisposing factors in hospitalized SCD patients are not available. Therefore, this issue was addressed to facilitate an early diagnosis and initiate appropriate prophylactic and treatment strategies. A retrospective observational study was conducted on patients with SCD who were admitted to an academic center in Saudi Arabia over a 10-year period. We identified 1054 admissions of 394 patients with SCD. Of the 3% of patients identified with VTE, 50% experienced pulmonary embolism (PE), 34.3% exhibited deep vein thrombosis (DVT), 6.3% exhibited cerebral vein thrombosis, and 9.4% showed other forms of VTE. In pregnant SCD patients, 6.4% developed a VTE event during their hospital admission. Of the risk factors, high white blood cell count, length of stay, and presence of any additional risk factor for VTE was associated significantly with higher risk of VTE. In our study, this risk seems to be much lower, which is likely attributed to the use of VTE prophylactic strategies implemented in our center. Nevertheless, further studies are needed to establish the ideal prophylactic strategy in patients with SCD.

Genetic Variation and Sickle Cell Disease Severity: A Systematic Review and Meta-Analysis

Importance

Sickle cell disease (SCD) is a monogenic disorder, yet clinical outcomes are influenced by additional genetic factors. Despite decades of research, the genetics of SCD remain poorly understood.

Objective

To assess all reported genetic modifiers of SCD, evaluate the design of associated studies, and provide guidelines for future analyses according to modern genetic study recommendations.

Data Sources

PubMed, Web of Science, and Scopus were searched through May 16, 2023, identifying 5290 publications.

Study Selection

At least 2 reviewers identified 571 original, peer-reviewed English-language publications reporting genetic modifiers of human SCD phenotypes, wherein the outcome was not treatment response, and the comparison was not between SCD subtypes or including healthy controls.

Data Extraction and Synthesis

Data relevant to all genetic modifiers of SCD were extracted, evaluated, and presented following STREGA and PRISMA guidelines. Weighted z score meta-analyses and pathway analyses were conducted.

Main Outcomes and Measures

Outcomes were aggregated into 25 categories, grouped as acute complications, chronic conditions, hematologic parameters or biomarkers, and general or mixed measures of SCD severity.

Results

The 571 included studies reported on 29 670 unique individuals (50% ≤ 18 years of age) from 43 countries. Of the 17 757 extracted results (4890 significant) in 1552 genes, 3675 results met the study criteria for meta-analysis: reported phenotype and genotype, association size and direction, variability measure, sample size, and statistical test. Only 173 results for 62 associations could be cross-study combined. The remaining associations could not be aggregated because they were only reported once or methods (eg, study design, reporting practice) and genotype or phenotype definitions were insufficiently harmonized. Gene variants regulating fetal hemoglobin and α-thalassemia (important markers for SCD severity) were frequently identified: 19 single-nucleotide variants in BCL11A, HBS1L-MYB, and HBG2 were significantly associated with fetal hemoglobin (absolute value of Z = 4.00 to 20.66; P = 8.63 × 10-95 to 6.19 × 10-5), and α-thalassemia deletions were significantly associated with increased hemoglobin level and reduced risk of albuminuria, abnormal transcranial Doppler velocity, and stroke (absolute value of Z = 3.43 to 5.16; P = 2.42 × 10-7 to 6.00 × 10-4). However, other associations remain unconfirmed. Pathway analyses of significant genes highlighted the importance of cellular adhesion, inflammation, oxidative and toxic stress, and blood vessel regulation in SCD (23 of the top 25 Gene Ontology pathways involve these processes) and suggested future research areas.

Conclusions and Relevance

The findings of this comprehensive systematic review and meta-analysis of all published genetic modifiers of SCD indicated that implementation of standardized phenotypes, statistical methods, and reporting practices should accelerate discovery and validation of genetic modifiers and development of clinically actionable genetic profiles.

The Role of Inflammation in The Cellular and Molecular Mechanisms of Cardiopulmonary Complications of Sickle Cell Disease

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in the lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD-associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

Prevalence and Risk Factors for Pulmonary Embolism in Pediatric Sickle Cell Disease: A National Administrative Database Study

Patients with sickle cell disease (SCD) have a high risk for venous thromboembolism which is associated with increased risk of mortality. Studies examining risk of pulmonary embolism (PE) in children with SCD are lacking. This study was conducted in children with SCD between 0-21 years of age using a nationwide administrative database in the United States- Pediatric Health Information System (PHIS) from January 2010 to June 2021. Diagnostic codes and imaging, procedure, and pharmaceutical billing codes were used to identify PE and potential clinical, demographic, and utilization risk factors. Logistic regression analyses were performed to assess association between risk factors and PE. We identified 22,631 unique patients with SCD with a median age of 10.8 years (range: <0.1-20.9). A total of 120 (0.53%) patients developed a PE with median age of 17.4 years (range: 6.6-20.9) at PE diagnosis. Patients with PE had longer hospitalization and more frequent ICU admissions than patients without PE (p < 0.001). Risk factors significantly associated with PE on multivariable analysis included older age, prior history of central venous line (CVL), acute chest syndrome, and apheresis. Mortality was not significantly different between those with and without PE. The prevalence of PE in hospitalized children with SCD was estimated to be 0.53%. Patients with PE had higher healthcare utilization characteristics. Factors significantly associated with PE suggest that the risk for PE in SCD may be related to the severity of disease state. Future trials are needed for risk stratification and PE prevention strategies in children with SCD.

The Genetic Landscape of Ischemic Stroke in Children - Current Knowledge and Future Perspectives

Stroke in childhood has multiple etiologies, which are mostly distinct from those in adults. Genetic discoveries over the last decade pointed to monogenic disorders as a rare but significant cause of ischemic stroke in children and young adults, including small vessel and arterial ischemic stroke. These discoveries contributed to the understanding that stroke in children may be a sign of an underlying genetic disease. The identification of these diseases requires a detailed medical and family history collection, a careful clinical evaluation for the detection of systemic symptoms and signs, and neuroimaging assessment. Establishing an accurate etiological diagnosis and understanding the genetic risk factors for stroke are essential steps to decipher the underlying mechanisms, optimize the design of tailored prevention strategies, and facilitate the identification of novel therapeutic targets in some cases. Despite the increasing recognition of monogenic causes of stroke, genetic disorders remain understudied and therefore under-recognized in children with stroke. Increased awareness among healthcare providers is essential to facilitate accurate diagnosis in a timely manner. In this review, we provide a summary of the main single-gene disorders which may present as ischemic stroke in childhood and describe their clinical manifestations. We provide a set of practical suggestions for the diagnostic work up of these uncommon causes of stroke, based upon the stroke subtype and imaging characteristics that may suggest a monogenic diagnosis of ischemic stroke in children. Current hurdles in the genetic analyses of children with ischemic stroke as well as future prospectives are discussed.

Age- and sex-specific rates of gall bladder disease in children with sickle cell disease

BACKGROUND

Children with sickle cell disease (SCD) have an increased risk for gallstones due to chronic hyperbilirubinemia from hemolysis. Although gallstones are a known complication, there is variability in estimates of disease burden and uncertainty in the association between sex and gall bladder disease (GBD).

METHODS

This was a retrospective cohort study of children with SCD using administrative claims data (January 1, 2014-December 31, 2018). Population-averaged multivariable panel-data logistic regression models were used to evaluate the association between GBD clinical encounters (outcome) and two exposures (age and sex). Annual GBD risk was calculated using predictive margins, adjusting for disease severity, transfusion frequency, and hydroxyurea exposure.

RESULTS

A total of 13,745 individuals (of 21,487 possible) met inclusion criteria. The population was evenly split across sex (49.5% female) with predominantly Medicaid insurance (69%). A total of 946 individuals (6.9%) had GBD, 432 (3.1%) had a gallstone complication, and 487 (3.5%) underwent cholecystectomy. The annual risk of GBD rose nonlinearly from 1 to 5% between ages 1 and 19 years with no difference between males and females. Cholecystectomy occurred primarily in individuals with GBD (87%), and neither age nor sex was associated with cholecystectomy in this population. High disease severity (compared with low) more than doubled the annual risk of GBD at all ages.

CONCLUSIONS

GBD is associated with age but not sex in children with SCD. Neither age nor sex is associated with risk of cholecystectomy. High disease severity increases the rate of GBD at all ages.

Exploring the Complex Network of Heme-Triggered Effects on the Blood Coagulation System

Excess labile heme, occurring under hemolytic conditions, displays a versatile modulator in the blood coagulation system. As such, heme provokes prothrombotic states, either by binding to plasma proteins or through interaction with participating cell types. However, despite several independent reports on these effects, apparently contradictory observations and significant knowledge gaps characterize this relationship, which hampers a complete understanding of heme-driven coagulopathies and the development of suitable and specific treatment options. Thus, the computational exploration of the complex network of heme-triggered effects in the blood coagulation system is presented herein. Combining hemostasis- and heme-specific terminology, the knowledge available thus far was curated and modeled in a mechanistic interactome. Further, these data were incorporated in the earlier established heme knowledge graph, "HemeKG", to better comprehend the knowledge surrounding heme biology. Finally, a pathway enrichment analysis of these data provided deep insights into so far unknown links and novel experimental targets within the blood coagulation cascade and platelet activation pathways for further investigation of the prothrombotic nature of heme. In summary, this study allows, for the first time, a detailed network analysis of the effects of heme in the blood coagulation system.

Sex as an Independent Risk Factor for Venous Thromboembolism in Sickle Cell Disease: A Cross-Sectional Study

Venous thromboembolism (VTE) affects up to 25% of individuals with sickle cell disease (SCD), but risk factors are not well characterized. We sought to measure the prevalence of VTE among SCD patients in our health system and to describe the relationship between medical history, biological sex, and VTE. We performed a retrospective chart review of SCD patients who visited an outpatient hematology clinic within Penn Medicine between June 2014 and June 2019. Demographics and medical history were compared across those with and without a history of VTE. We developed a logistic regression model to describe factors independently associated with VTE. Of 597 patients with SCD who were identified, 147 (24.6%) had a history of VTE; 100 were female and 47 were male. In the regression model, female sex was independently associated with history of VTE (odds ratio 1.91, 95% confidence interval 1.26-2.91), as were pulmonary hypertension, hydroxyurea use, and history of stroke. Among females only, 49.7% were parous and 18.8% had used oral contraceptives, and these proportions did not differ by history of VTE. One-quarter of the SCD patients in our health system had a history of VTE, confirming significantly higher rates than in the general population. Females had twice the odds of VTE compared to males, highlighting an important sex disparity in SCD disease outcomes and raising questions regarding optimal pregnancy and contraceptive care for females with SCD.

COVID-19 outcomes in sickle cell disease and sickle cell trait

Throughout the Coronavirus Disease 2019 (COVID-19) pandemic, understanding the effects of COVID-19 on persons with Sickle Cell Disease (SCD) and Sickle Cell Trait (SCT) has garnered interest. Patients with SCD diagnosed with COVID-19 utilize the emergency department and are hospitalized at significantly higher rates compared to the general population, with vaso-occlusive crisis and acute chest syndrome as the leading presentations. Whether SCD alone increases the likelihood of severe COVID-19 illness remains uncertain; however, potential risk factors for severe disease among patients with SCD include older age, frequent acute care visits for pain, haemoglobin SC disease, and pre-existing end-organ disease. SCT status may also influence COVID-19 outcomes, particularly among those with pre-existing co-morbidities. Corticosteroids in patients with SCD and COVID-19 should be used with extreme caution given strong associations between corticosteroid exposure and severe vaso-occlusive crisis, with prophylactic transfusion administered if corticosteroids are deemed necessary. Hydroxyurea may be protective in COVID-19.

Characteristics and outcomes of stroke hospitalizations in patients with sickle cell disease and moyamoya syndrome

OBJECTIVES

Stroke is the leading cause of death in patients with Sickle cell disease (SCD). Here, we detail the burden of Moyamoya syndrome (MMS) as a cause of stroke in patients with SCD.

MATERIALS AND METHODS

A review of SCD-related hospital discharges was conducted utilizing the National Inpatient Sample. Rates of stroke hospitalization, risk factors, procedures, and outcomes were compared between patients with SCD-MMS and SCD alone. Univariate analyses including T-test, Wilcoxon Rank-Sum test, Chi-square were performed to compare risk factors and outcomes. Multivariable regression was used to identify predictors of stroke unique to each population.

RESULTS

Stroke occurred in 9.8% of SCD-MMS hospitalizations versus 0.5% of those involving patients with SCD alone (OR = 20.71, p < 0.001). Patients with SCD-MMS developed stroke at younger ages and with fewer comorbidities compared to those with SCD alone. Stroke hospitalizations in SCD-MMS involved a greater number of procedures (90.5% vs. 79.3%, p = 0.007), but were more likely to result in favorable discharge (58.5% vs. 44.2%, p = 0.005). The presence of anemia during hospitalization was a significant risk factor for stroke in both cohorts. Long-term antiplatelet use was protective against stroke (OR = 0.42, p = 0.008) only in the SCD-MMS cohort.

CONCLUSIONS

MMS confers a 20-fold increased risk of stroke among patients with SCD and appears to be an important cause of recurrent stroke in this population. Anemia is one of the most significant risk factors for stroke, while antiplatelet use appears to confer a protective benefit.

Venous thromboembolism prophylaxis in hospitalized sickle cell disease and sickle cell trait patients

INTRODUCTION

Sickle trait (Hb SA) or sickle disease (Hb SS) carries increased risk of venous thromboembolism (VTE). Hb SS patients are young and lack common comorbid conditions that qualify them for VTE prophylaxis (VTEP).

METHODS

Retrospective, multicenter analysis of Hb SS/Hb SA adult patients between January 2013 and December 2018.

RESULTS

There were 803 Hb SA (525 patients) and 1020 Hb SS admissions (262 patients). VTEP use was similar between Hb SA and controls (42% vs. 46%; p-value = .06) and Hb SS and controls (45% vs. 42%; p-value = .13). Hb SS/Hb SA patients more frequently received more than half of prescribed doses of VTEP. In multivariate analysis, increasing age and longer hospitalizations were positive predictors. Odds of VTEP use varied with treatment site for Hb SS patients, whereas comorbid conditions, admission hemoglobin and platelet count were not predictive. By contrast, in Hb SA patients, comorbid conditions, higher admission hemoglobin, and higher admission platelet counts raised the odds of VTEP being offered.

CONCLUSIONS

VTEP is underused in Hb SS/Hb SA patients. There may be a trend toward offering more VTEP in Hb SS disease, but not in Hb SA patients, where VTEP prescribing is driven by comorbid conditions rather than genotype. Patient compliance does not appear to play a major role, but intercenter variability suggests provider education may improve VTEP use.

P- and E- selectin in venous thrombosis and non-venous pathologies

Venous thromboembolism is a very common and costly health problem worldwide. Anticoagulant treatment for VTE is imperfect: all have the potential for significant bleeding, and none prevent the development of post thrombotic syndrome after deep vein thrombosis or chronic thromboembolic pulmonary hypertension after pulmonary embolism. For these reasons, alternate forms of therapy with improved efficacy and decreased bleeding are needed. Selectins are a family (P-selectin, E-selectin, L-selectin) of glycoproteins that facilitate and augment thrombosis, modulating neutrophil, monocyte, and platelet activity. P- and E-selectin have been investigated as potential biomarkers for thrombosis. Inhibition of P-selectin and E-selectin decrease thrombosis and vein wall fibrosis, with no increase in bleeding. Selectin inhibition is a promising avenue of future study as either a stand-alone treatment for VTE or as an adjunct to standard anticoagulation therapies.

Thromboprophylaxis Reduced Venous Thromboembolism in Sickle Cell Patients with Central Venous Access Devices: A Retrospective Cohort Study

Sickle cell disease (SCD) induces a chronic prothrombotic state. Central venous access devices (CVADs) are commonly used for chronic transfusions and iron chelation in this population. CVADs are an additional venous thromboembolism (VTE) risk factor. The role of thromboprophylaxis in this setting is uncertain. The objectives are: (1) to determine whether thromboprophylaxis reduces VTE risk in SCD patients with CVAD and (2) to explore characteristics associated with VTE risk. We identified adults with SCD and CVAD intended for chronic use (≥3 months) at two comprehensive SCD centers. Thromboprophylaxis presence; type; intensity; and patient-, catheter-, and treatment-related VTE risk factors were recorded. Among 949 patients, 49 had a CVAD (25 without and 24 with VTE prophylaxis). Thromboprophylaxis type and intensity varied widely. Patients without thromboprophylaxis had higher VTE rates (rate ratio (RR) = 4.0 (95% confidence interval: 1.2−12.6), p = 0.02). Hydroxyurea was associated with lower VTE rates (RR = 20.5 (6.4−65.3), p < 0.001). PICC lines and Vortex and Xcela Power implantable devices were associated with higher rates compared with Port-a-Cath (RR = 5.8 (1.3−25.9), p = 0.02, and RR = 58.2 (15.0−225.0), p < 0.001, respectively). Thromboprophylaxis, hydroxyurea, and CVAD subtype were independently associated with VTE. The potentially protective role of thromboprophylaxis and hydroxyurea for VTE prevention in patients with SCD and CVAD merits further exploration.

Ulcerative colitis in patients with sickle cell disease: a rare but important co-morbidity

COVID-19: Coronavirus disease 2019; HIC: high-income countries; IBD: inflammatory bowel disease; LMIC: low- and middle-income countries; PUCAL: paediatric ulcerative colitis activity index; SCD: sickle cell disease; UC: ulcerative colitis.

Association Between Patent Foramen Ovale and Overt Ischemic Stroke in Children With Sickle Cell Disease

Ischemic stroke is one of the most devastating complications of sickle cell anemia (SCA). Previous studies have shown that intracardiac shunting including patent foramen ovale (PFO) can be a potential risk factor for stroke in children with SCA. This study investigates the association between PFO and overt ischemic stroke in the DISPLACE (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) study cohort of 5,247 children with SCA of whom 1,414 had at least one clinical non-contrast transthoracic echocardiogram. Presence of PFO was taken from the clinical report. Further, we assessed the association between PFO and other clinical and hemolytic factors in children with SCA such as history of abnormal sickle stroke screen [elevated Transcranial Doppler ultrasound (TCD) velocity] and patient's baseline hemoglobin. In 642 children for whom all data were available, the adjusted odds ratio (OR) for overt stroke was higher in those with PFO but this was not statistically significant (OR: 1.49, 95% CI: 0.20-11.03, p = 0.6994). With an OR of 0.85, the study suggested less PFOs in those with abnormal TCD, but this was not statistically significant (95% CI: 0.17-4.25, p = 0.8463). Overall, the prevalence of PFO in this large sub study of non-contrast echocardiography amongst children with SCA is much lower than previous smaller studies using bubble contrast echocardiography. Overt stroke was non-statistically more common in children with SCA and PFO, but there was no evidence that PFO was more common in those with abnormal TCD, the most important pediatric sickle stroke screen.

Predicting risk factors for thromboembolic complications in patients with sickle cell anaemia - lessons learned for prophylaxis

Objective

To assess the clinical and laboratory predictors of venous thromboembolism (VTE) in patients with sickle cell anaemia (SCA) and its relationship to morbidity and mortality.

Methods

This retrospective case–control study analysed data from patients with SCA that experienced VTE compared with matched control patients with SCA but no VTE (2:1 ratio).

Results

A total of 102 patients with SCA were enrolled (68 cases with VTE and 34 controls). Amongst the 68 cases (median age, 29.5 years), 26 (38.2%) presented with isolated pulmonary embolism (PE). A higher prevalence of splenectomy (73.5% versus 35.3%) was observed in the cases compared with the controls. A significantly higher prevalence of central venous catheter (CVC) insertion (42.6% versus 8.8%) was observed in the cases compared with the controls. High white blood cell counts, serum lactic dehydrogenase (LDH), bilirubin and C-reactive protein (CRP) and low haemoglobin (Hb) and HbF were significant risk factors for VTE. Forty-two cases (61.8%) developed acute chest syndrome, 10 (14.7%) had a stroke and seven (10.3%) died.

Conclusions

VTE in patients with SCA has a high impact on morbidity and mortality. PE was the leading presentation of VTE, with CVC insertion, high LDH, bilirubin, CRP and white blood cell counts along with low Hb and HbF constituting other significant risk factors.

Evaluation of point-of-care International Normalized Ratio in sickle cell disease

Background

Point‐of‐care (POC) International Normalized Ratio (INR) measurement provides efficient monitoring of warfarin therapy; however, its reliability may be affected in patients with anemia, such as those with sickle cell disease (SCD).

Objectives

To evaluate the correlation of POC‐INR to clinical laboratory INR (CL‐INR) in SCD and use of a correction factor.

Patient/Methods

In this retrospective study, the accuracy of POC‐INR compared to CL‐INR was evaluated in a cohort of patients with SCD and in a non‐SCD Black cohort.

Results

Despite the difference in anemia, the SCD cohort showed a similar percentage of in‐range POC‐INR values as observed in the non‐SCD cohort (37% vs 42%). The SCD cohort was randomly divided to form discovery and validation cohorts. In the discovery cohort, 86% of POC‐INRs were in range when the POC‐INRs were ˂4.0, but only 24% were in range if POC‐INRs were ≥4.0. A linear regression of CL‐INR versus POC‐INR for POC‐INR values ≥4.0 yielded a coefficient of 0.72 (95% confidence interval, 0.69‐0.75); Multiplying POC‐INR by this correction factor, rounded to 0.7 for ease of use in clinical practice, improved the proportion of in‐range POC‐INR values ≥4.0 from 24% to 100% in the SCD discovery cohort and from 19% to 95% in the SCD validation cohort. Similar findings applied to analyses of the non‐SCD cohort.

Conclusions

POC‐INR and CL‐INR in patients with SCD are similar when POC‐INR is <4.0, and the accuracy of POC‐INR values ≥4.0 can be improved by applying an institution‐specific correction factor.

NLRP3 inflammasome and bruton tyrosine kinase inhibition interferes with upregulated platelet aggregation and in vitro thrombus formation in sickle cell mice

The nucleotide-binding domain leucine-rich repeat containing protein 3 (NLRP3) inflammasome is a critical inflammatory mechanism identified in platelets, which controls platelet activation and aggregation. We have recently shown that the platelet NLRP3 inflammasome is upregulated in sickle cell disease (SCD), which is mediated by Bruton tyrosine kinase (BTK). Here, we investigated the effect of pharmacological inhibition of NLRP3 and BTK on platelet aggregation and the formation of in vitro thrombi in Townes SCD mice. Mice were injected for 4 weeks with the NLRP3 inhibitor MCC950, the BTK inhibitor ibrutinib or vehicle control. NLRP3 activity, as monitored by caspase-1 activation, was upregulated in platelets from SCD mice, which was dependent on BTK. Large areas of platelet aggregates detected in the liver of SCD mice were decreased when mice were treated with MCC950 or ibrutinib. Moreover, platelet aggregation and in vitro thrombus formation were upregulated in SCD mice and were inhibited when mice were subjected to pharmacological inhibition of NLRP3 and BTK. Targeting the NLRP3 inflammasome might be a novel approach for antiplatelet therapy in SCD.

The molecular basis for the prothrombotic state in sickle cell disease

The genetic and molecular basis of sickle cell disease (SCD) has long since been characterized but the pathophysiological basis is not entirely defined. How a red cell hemolytic disorder initiates inflammation, endothelial dysfunction, coagulation activation and eventually leads to vascular thrombosis, is yet to be elucidated. Recent evidence has demonstrated a high frequency of unprovoked/recurrent venous thromboembolism (VTE) in SCD, with an increased risk of mortality among patients with a history of VTE. Here, we thoroughly review the molecular basis for the prothrombotic state in SCD, specifically highlighting emerging evidence for activation of overlapping inflammation and coagulation pathways, that predispose to venous thromboembolism. We share perspectives in managing venous thrombosis in SCD, highlighting innovative therapies with the potential to influence the clinical course of disease and reduce thrombotic risk, while maintaining an acceptable safety profile.