Venous Thromboembolism in Children with Sickle Cell Disease: A Retrospective Cohort Study

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.

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.

Thrombosis risk with haemoglobin C trait and haemoglobin C disease: A systematic review

The thrombotic risk with haemoglobin C trait (HbAC) or haemoglobin C disease (HbCC) is unclear. However, individuals with HbCC have demonstrated chronic haemolysis, higher blood viscosity and altered rheology when compared to individuals with wild-type haemoglobin (HbAA). These physiological alterations may theoretically translate to increased risk of thrombosis; therefore, a systematic literature review was performed to investigate the possible association between HbAC and/or HbCC and thrombosis. Twenty-two studies met inclusion criteria representing 782 individuals with HbAC (n = 694) or HbCC (n = 88). Fifteen studies described the presence/absence of venous thromboembolism (VTE) in patients with HbAC (n = 685) or HbCC (n = 79), while seven studies described patients with HbAC (n = 9) or HbCC (n = 9) and arterial thrombosis. Most (n = 20) studies were case reports or case series; however, two studies suggested a potential increased VTE risk with HbAC compared to HbAA in (i) all patients (OR 2.2, 95% CI: 0.9-5.5) and in (ii) pregnant individuals (RR 3.7, 95% CI 0.9-16). This review is the largest assessment of patients with HbC trait or disease and thrombosis to date; despite its limitations, the findings suggest HbC may be a predisposing risk factor to thrombosis. Prospective cohort studies are warranted to definitively elucidate the risk of thrombosis in this population.

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.

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.

Use of infusion ports in patients with sickle cell disease: Indications and complications

BACKGROUND

Peripheral venous access in patients with sickle cell disease (SCD) can become difficult over time due to frequent access and scarring. Infusion ports provide reliable central venous access. Deep venous thrombosis (DVT) and infections are complications associated with SCD and infusion ports.

METHODS

We performed a 17.5-year single-institution retrospective chart review (January 2000 to July 2018) with literature review regarding use of infusion ports in patients with SCD.

RESULTS

We identified 32 patients with infusion ports placed for a total of 63 devices (48 for chronic transfusion [CT] and 15 for poor venous access [PVA], not on CT) for a total of 99,272 catheter days. The mean age at first insertion was 8 years (range 1-20 years). Complications included malfunction, infection, thrombosis, difficult access, and pain over infusion port site. The rate of infection was 0.2 per 1000 catheter days. Thrombosis was identified in three devices (5%) in three patients (9%), with a rate of 0.03 per 1000 catheter days. There was no difference in complications by site in either the left or right subclavian vein (p = 1). The rate of premature removal was 0.36 per 1000 catheter days, which was higher among patients with infusion ports solely for PVA (0.87 per 1000 catheter days) compared with those placed for CT (0.29 per 1000 catheter days).

CONCLUSION

Infusion ports in patients with SCD was associated with low rates of thrombosis, infection, and malfunction, and may be considered as an alternative to frequent intravenous access, especially in patients requiring CT.

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.

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

Sickle cell disease (SCD) patients are at a four- to 100-fold increased risk for thrombosis compared with the general population, although the mechanisms and risk factors are not clear. We investigated the incidence and predictors for thrombosis in a retrospective, longitudinal cohort of 1193 pediatric and adult SCD patients treated at our institution between January 2008 and December 2017. SCD diagnosis and thrombotic complications were identified using International Classification of Diseases coding and verified through medical chart review. Clinical and laboratory data were extracted from the medical records. With a median follow-up of 6.4 years, 208 (17.4%) SCD patients experienced 352 thrombotic events (64 strokes, 288 venous thromboembolisms [VTE]). Risk factors for stroke included older age and HbSS/Sβ0-genotype and a lower hemoglobin (Hb) F% in the subset of HbSS/Sβ0-genotype patients (P < .05). VTE risk was independently associated with lower estimated glomerular filtration rate, hydroxyurea (HU) use, HbSS/Sβ0 genotype, and higher white blood cell (WBC) counts and Hb (P ≤ .03). Two thrombomodulin gene variants previously associated with thrombosis in the general African American population, THBD rs2567617 (minor allele frequency [MAF] 0.25; odds ratio [OR], 1.5; P = .049) and THBD rs1998081 (MAF, 0.24; OR, 1.5; P = .059), were associated with thrombosis in this cohort. In summary, thrombotic complications are common, and several traditional and SCD-specific risk factors are associated with thrombotic risk. Future studies integrating clinical, laboratory, and genetic risk factors may improve our understanding of thrombosis and guide intervention practices in SCD.

Venous Thromboembolism among Noncritically Ill Hospitalized Children: Key Considerations for the Pediatric Hospital Medicine Specialist

Venous thromboembolism (VTE) is a leading cause of morbidity and preventable harm among noncritically ill hospitalized children. Several clinical factors relevant to the noncritically ill hospitalized child significantly increase the risk of VTE including the presence of central venous catheters, systemic inflammation, and prolonged immobilization. Although risk mitigation strategies have been described, the diagnosis, treatment, and prevention of VTE require standardization of institutional practices combined with multidisciplinary collaboration among pediatric hospitalists, hematologists, and other care providers. In this narrative review, we summarize the epidemiology of VTE, risk models identifying high-risk conditions associated with VTE, and prevention and treatment strategies. We further describe successful quality improvement efforts implementing institutional VTE risk stratification and thromboprophylaxis procedures. Finally, we highlight unique challenges facing pediatric hospital medicine specialists in the era of the COVID-19 pandemic, including caring for adults admitted to pediatric hospital units, and describe future research opportunities for VTE in the noncritically ill hospitalized child.

Venous thromboembolism in children with central nervous system tumors: Comparison of an institutional cohort to a national administrative database

BACKGROUND

Central nervous system (CNS) tumors are the second most common malignancy of childhood, and published data on venous thromboembolism (VTE) rate and risk factors for these patients are outdated or incomplete. Here, we determine the cumulative incidence and risk factors for VTE in this population.

PROCEDURE

VTE diagnosis and associated clinical risk factors were abstracted and analyzed for two cohorts of children (0-21 years) diagnosed with CNS tumors between January 1, 2010 to September 30, 2018. The first study was a retrospective single institution cohort study. The initial observations were confirmed across multiple pediatric hospitals using the Pediatric Health Information System (PHIS) administrative database.

RESULTS

The single-institution cohort included 338 patients aged 3 days to 20.9 years (median age, 8.6 years); VTE developed in eight (2.4%) patients. The PHIS cohort included 17 634 patients aged from 0 to 21.9 years (median: 9.5 years); VTE developed in 354 (2.0%) patients. Univariate analysis for the single-institution cohort identified central venous catheter (CVC) placement as a risk factor for VTE (odds ratio [OR] 8.40, 95% confidence interval [CI] 1.43-49.41, P = .0186). Multivariable analysis of the PHIS dataset identified CVC placement (OR 1.97, 95% CI 1.57-2.46; P < .0001), obesity (OR 2.96, 95% CI 1.21-7.26; P = .0177), and more than one hospital admission (OR 3.54, 95% CI 2.69-4.64; P < .0001) as significant predictors of VTE. VTE diagnosis was not associated with increased mortality in either cohort.

CONCLUSIONS

The VTE rate in children with CNS tumors is low (2%). CVC placement was identified as a modifiable risk factor in both cohorts.

Risk Factors for the Development of Hospital-Associated Venous Thromboembolism in Adult Patients Admitted to a Children's Hospital

BACKGROUND AND OBJECTIVES

Hospital-associated venous thromboembolism (HA-VTE) is a leading cause of preventable in-hospital mortality in adults. Our objective was to describe HA-VTE and evaluate risk factors for its development in adults admitted to a children's hospital, which has not been previously studied. We also evaluated the performance of commonly used risk assessment tools for HA-VTE.

METHODS

A case-control study was performed at a freestanding children's hospital. Cases of HA-VTE in patients ≥18 years old (2013-2017) and age-matched controls were identified. We extracted patient and HA-VTE characteristics and HA-VTE risk factors on the basis of previous literature. Thrombosis risk assessment was performed retrospectively by using established prospective adult tools (Caprini and Padua scores).

RESULTS

Thirty-nine cases and 78 controls were identified. Upper extremities were the most common site of thrombosis (62%). Comorbid conditions were common (91.5%), and malignancy was more common among case patients than controls (P = .04). The presence of a central venous catheter (P < .01), longer length of stay (P < .01), ICU admission (P = .005), and previous admission within 30 days (P = .01) were more common among case patients when compared with controls. Median Caprini score was higher for case patients (P < .01), whereas median Padua score was similar between groups (P = .08).

CONCLUSIONS

HA-VTE in adults admitted to children's hospitals is an important consideration in a growing high-risk patient population. HA-VTE characteristics in our study were more similar to published data in pediatrics.

American Society of Hematology 2019 guidelines for sickle cell disease: cardiopulmonary and kidney disease

BACKGROUND

Prevention and management of end-organ disease represent major challenges facing providers of children and adults with sickle cell disease (SCD). Uncertainty and variability in the screening, diagnosis, and management of cardiopulmonary and renal complications in SCD lead to varying outcomes for affected individuals.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about screening, diagnosis, and management of cardiopulmonary and renal complications of SCD.

METHODS

ASH formed a multidisciplinary guideline panel that included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Mayo Evidence-Based Practice Research Program supported the guideline development process, including performing systematic evidence reviews up to September 2017. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE evidence-to-decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 10 recommendations for screening, diagnosis, and management of cardiopulmonary and renal complications of SCD. Recommendations related to anticoagulation duration for adults with SCD and venous thromboembolism were also developed.

CONCLUSIONS

Most recommendations were conditional due to a paucity of direct, high-quality evidence for outcomes of interest. Future research was identified, including the need for prospective studies to better understand the natural history of cardiopulmonary and renal disease, their relationship to patient-important outcomes, and optimal management.

Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework

It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.

Treatment-Related Outcomes in Paget-Schroetter Syndrome-A Cross-Sectional Investigation

OBJECTIVE

To investigate treatment-related outcomes, namely radiological clot resolution, post-thrombotic syndrome (PTS), and health related quality-of-life (HRQoL) scores, in children with Paget-Schroetter syndrome (PSS) undergoing multidisciplinary management, including anticoagulation and decompressive rib-resection surgery, with or without thrombolytic therapy.

STUDY DESIGN

We identified all patients treated for PSS at our institution between the years 2010 and 2017. Baseline clinical and radiologic data were abstracted from medical records. Two validated survey instruments to quantify PTS and HRQoL were mailed to eligible patients. Standard statistical methods were used to summarize these measures.

RESULTS

In total, 22 eligible patients were identified; 10 were treated with thrombolysis followed by anticoagulation and rib resection, and 12 were treated with anticoagulation and rib resection alone. Nineteen patients responded to the survey instruments. Median age at deep vein thrombosis diagnosis and survey completion were 16.3 and 20.4 years, respectively. Nineteen of 22 patients had thrombus resolution on radiologic follow-up. Fourteen of 19 survey respondents reported signs/symptoms of PTS of which the majority (12/14) reported mild PTS. Aggregate total, physical, and psychosocial HRQoL scores reported were 90.6, 96.7, and 93.3, respectively. Thrombolytic therapy was not associated with a significant improvement in radiologic, clinical or HRQoL outcomes.

CONCLUSIONS

Most patients with PSS had complete thrombus resolution on imaging. Only 11% of survey respondents reported moderate PTS. The entire cohort reported excellent HRQoL scores. The role for thrombolytic therapy in the management of childhood PSS remains incompletely elucidated.

Impact of erythrocytapheresis on natural anticoagulant levels in children with sickle cell disease: A pilot study

Venous thromboembolism (VTE) is being increasingly recognized in children with sickle cell disease (SCD). In a retrospective cohort study, we identified bilateral central venous catheter (CVC) placement as an independent risk factor for VTE. At our institution, the only indication for bilateral CVC placement in children with SCD is erythrocytapheresis. To investigate the impact of erythrocytapheresis on coagulation, we measured levels of natural anticoagulants in 11 patients with SCD on chronic erythrocytapheresis, immediately before and after apheresis. We demonstrated a statistically significant reduction in most parameters. Additional studies are needed to further investigate the exact etiology and clinical impact of this acute decrease.

Overcoming challenges of venous thromboembolism in sickle cell disease treatment

INTRODUCTION

Venous thromboembolism (VTE) is a common comorbid condition found in sickle cell disease (SCD) and is associated with increased mortality for adults with SCD. The pathophysiology that leads to the thrombophilic state in SCD has been previously reviewed; however, evidence-based guidelines to aid in diagnosis, prevention, and management of VTE are lacking. Areas covered: This review article will cover the pathophysiology underlying the hypercoagulable state, the epidemiology of VTE, and management strategies of VTE in SCD. Expert opinion: Providers should have a high suspicion for diagnosing VTE to help reduce morbidity and mortality in the SCD population. Unlike other thrombophilias, the risk of life-threatening anemia while being treated with anticoagulation is compounded with the potential complications surrounding red blood cell transfusions in this population (i.e. alloimmunization, hyperhemolysis) and this provides another complexity to managing VTE in this population. Clinical trials evaluating the risk and benefit of treatment and treatment duration are needed.