Markers of severe vaso-occlusive painful episode frequency in children and adolescents with sickle cell anemia

Unraveling the Complexity of Vaso-Occlusive Crises in Sickle Cell Disease: Insights from a Resource-Limited Setting

Background/Objectives: This study investigated vaso-occlusive crises (VOCs) in sickle cell disease in Lubumbashi, Democratic Republic of Congo, aiming to understand the disease complexities amidst limited resources. With sickle cell hemoglobinopathies on the rise in sub-Saharan Africa, this nine-year study explored factors associated with VOCs and hematological components. Methods: This study comprised 838 patients, analyzing VOCs and hematological changes over time. Demographic characteristics and blood composition changes were carefully categorized. A total of 2910 crises were observed and managed, with analyses conducted on severity, localization, and age groups using statistical methods. Results: The majority of crises were mild or moderate, primarily affecting osteoarticular regions. Statistical analysis revealed significant disparities in crisis intensity based on location and age. The association between blood samples and the number of comorbidities was investigated. Significant positive associations were found for all parameters, except monocytes, indicating a potential link between blood variables and complication burden. Survival analysis using Cox regression was performed to predict the probability of experiencing a second crisis. No significant effects of medication or localization were observed. However, intensity (p < 0.001), age (p < 0.001), and gender (p < 0.001) showed significant effects. Adjusted Hazard Ratios indicated increased risk with age and male gender and reduced risk with mild or severe crisis intensity compared to light. Conclusions: This research sheds light on the complexities of VOCs in resource-limited settings where sickle cell disease is prevalent. The intricate interplay between clinical, laboratory, and treatment factors is highlighted, offering insights for improved patient care. It aims to raise awareness of patient challenges and provide valuable information for targeted interventions to alleviate their burden.

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.

Gene expression changes in sickle cell reticulocytes and their clinical associations

Transcriptional changes in compensatory erythropoiesis in sickle cell anemia (SCA) and their disease modulation are unclear. We detected 1226 differentially expressed genes in hemoglobin SS reticulocytes compared to non-anemic hemoglobin AA controls. Assessing developmental expression changes in hemoglobin AA erythroblasts for these genes suggests heightened terminal differentiation in early erythroblasts in SCA that diminishes toward the polychromatic to orthochromatic stage transition. Comparison of reticulocyte gene expression changes in SCA with that in Chuvash erythrocytosis, a non-anemic disorder of increased erythropoiesis due to constitutive activation of hypoxia inducible factors, identified 453 SCA-specific changes attributable to compensatory erythropoiesis. Peripheral blood mononuclear cells (PBMCs) in SCA contain elevated proportions of erythroid progenitors due to heightened erythropoiesis. Deconvolution analysis in PBMCs from 131 SCA patients detected 54 genes whose erythroid expression correlated with erythropoiesis efficiency, which were enriched with SCA-specific changes (OR = 2.9, P = 0.00063) and annotation keyword "ubiquitin-dependent protein catabolic process", "protein ubiquitination", and "protein polyubiquitination" (OR = 4.2, P = 7.5 × 10-5). An erythroid expression quantitative trait locus of one of these genes, LNX2 encoding an E3 ubiquitin ligase, associated with severe pain episodes in 774 SCA patients (OR = 1.7, P = 3.9 × 10-5). Thus, erythroid gene transcription responds to unique conditions within SCA erythroblasts and these changes potentially correspond to vaso-occlusive manifestations.

Does TGFBR3 Polymorphism Increase the Risk of Silent Cerebral Infarction in Egyptian Children with Sickle Cell Disease?

OBJECTIVES

To evaluate the relationship between TGFBR3 rs284875 single nucleotide polymorphism (SNP) state and silent cerebral infarction (SCI) in asymptomatic patients with sickle cell disease (SCD).

METHODS

A cross-sectional study was conducted on 50 children with SCD above 2 y of age followed up at the hematology outpatient clinic of Alexandria University Children's Hospital in Egypt. Twenty-four healthy children were included as a control group. All patients included in the study were subjected to complete history and clinical examination. Real-time polymerase chain reaction was performed on patients and controls for identification of SNP rs284875 of the TGFBR3 gene. A magnetic resonance imaging (MRI) of the brain were performed only on patients for detection of SCI.

RESULTS

Fifty SCD patients were enrolled (26 males and 24 females), with a median age of 10.9 y (2.3-17.8 y), and 24 children as healthy control for the studied SNP. Thirty-five (70%) patients had homozygous SCD, while 30% had sickle β-thalassemia. The brain MRI was normal in all the patients except for 2 patients who had features of SCI. The TGFBR3 rs284875 SNP was detected in 15 (30%) patients in the homozygous state (GG) versus only 1 (4.2%) child from the control group (p = 0.003). The prevalence of SCI was low in the study population and there was no statistically significant relationship between the TGFBR3 rs284875 SNP status and the presence of SCI in the brain MRI (p = 0.621).

CONCLUSIONS

This study confirmed a low prevalence of SCI in the SCD patient included in the study. The TGFBR3 rs284875 SNP did not significantly increase SCI among those patients.

The pleiotropic effects of α-thalassemia on HbSS and HbSC sickle cell disease: Reduced erythrocyte cation co-transport activity, serum erythropoietin, and transfusion burden, do not translate into increased survival

α-Thalassemia is one of the most important genetic modulators of sickle cell disease (SCD). Both beneficial and detrimental effects have been described previously. We use a 12-year data set on a large cohort of patients with HbSS (n = 411) and HbSC (n = 146) to examine a wide range of these clinical and laboratory associations. Our novel findings are that α-thalassemia strongly reduces erythrocyte potassium chloride co-transporter (KCC) activity in both HbSS and HbSC (p = .035 and p = .00045 respectively), suggesting a novel mechanism through which α-thalassemia induces a milder phenotype by reducing red cell cation loss. This may be particularly important in HbSC where reduction in mean cell hemoglobin concentration is not seen and where KCC activity has previously been found to correlate with disease severity. Additionally, we show that α-thalassemia not only increases hemoglobin in patients with HbSS (p = .0009) but also reduces erythropoietin values (p = .0005), demonstrating a measurable response to improved tissue oxygenation. We confirm the reno-protective effect of α-thalassemia in patients with HbSS, with reduced proteinuria (p = .003) and demonstrate a novel association with increased serum sodium (p = .0004) and reduced serum potassium values (p = 5.74 × 10^-10 ). We found patients with α-thalassemia had a reduced annualized transfusion burden in both HbSS and HbSC, but α-thalassemia had no impact on annualized admission rates in either group. Finally, in a larger cohort, we report a median survival of 62 years in patients with HbSS (n = 899) and 80 years in those with HbSC (n = 240). α-thalassemia did not influence survival in HbSS, but a nonsignificant trend was seen in those with HbSC.

Demand-only patient-controlled analgesia for treatment of acute vaso-occlusive pain in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a chronic illness that is associated with frequent admissions for vaso-occlusive episodes (VOE). Opioids are frequently utilized in pain management, but dosing is often provider dependent. Opioids cause both short-term and long-term side effects, so the minimal effective dose is desired. This study examined demand-only patient-controlled analgesia (PCA) in pediatric patients.

METHODS

A new clinical practice guideline (CPG) for a single institution was implemented, which eliminated basal infusion dosing for PCAs on hospital admission. The primary aim of this retrospective study was to evaluate length of stay (LOS) before and after implementation of a CPG of demand-only PCA and, in a selected subpopulation, addition of short-term methadone. Secondary aims included opioid utilization, acute chest syndrome (ACS), and hypoxia. Inclusion criteria included SCD, ≤21 years of age, uncomplicated VOE admission, and ≥ 3 and ≤ 8 hospital admissions for SCD pain control within one calendar year.

RESULTS

LOS decreased postintervention (7.2 ± 5.1 vs 4.5 ± 3.8 days, P < 0.001). Mean total opioid utilization in morphine equivalents mg/kg markedly decreased between the cohorts (13.3 ± 33.8 vs 3.6 ± 3.0, P < 0.001). ACS (21.9% vs 2.8%, P = 0.004) and hypoxia (28% vs 6.9%, P< 0.001) decreased significantly as well.

CONCLUSION

Bolus PCA dosing of opioids resulted in decreased LOS and reductions in opioid utilization, hypoxia, and ACS.

Determinants of severity in sickle cell disease

Sickle cell disease is a very variable condition, with outcomes ranging from death in childhood to living relatively symptom free into the 8^th decade. Much of this variability is unexplained. The co-inheritance of α thalassaemia and factors determining HbF levels significantly modify the phenotype, but few other significant genetic variants have been identified, despite extensive studies. Environmental factors are undoubtedly important, with socio-economics and access to basic medical care explaining the huge differences in outcomes between many low- and high-income countries. Exposure to cold and windy weather seems to precipitate acute complications in many people, although these effects are unpredictable and vary with geography. Many studies have tried to identify prognostic factors which can be used to predict outcomes, particularly when applied in infancy. Overall, low haemoglobin, low haemoglobin F percentage and high reticulocytes in childhood are associated with worse outcomes, although again these effects are fairly weak and inconsistent.

Vasoconstriction Response to Mental Stress in Sickle Cell Disease: The Role of the Cardiac and Vascular Baroreflexes

Recent studies have shown that individuals with sickle cell disease (SCD) exhibit greater vasoconstriction responses to physical autonomic stressors, such as heat pain and cold pain than normal individuals, but this is not the case for mental stress (MTS). We sought to determine whether this anomalous finding for MTS is related to inter-group differences in baseline cardiac and vascular autonomic function. Fifteen subjects with SCD and 15 healthy volunteers participated in three MTS tasks: N-back, Stroop, and pain anticipation (PA). R-R interval (RRI), arterial blood pressure and finger photoplethysmogram (PPG) were continuously monitored before and during these MTS tasks. The magnitude of vasoconstriction was quantified using change in PPG amplitude (PPGa) from the baseline period. To represent basal autonomic function, we assessed both cardiac and vascular arms of the baroreflex during the baseline period. Cardiac baroreflex sensitivity (BRSc) was estimated by applying both the "sequence" and "spectral" techniques to beat-to-beat measurements of systolic blood pressure and RRIs. The vascular baroreflex sensitivity (BRSv) was quantified using the same approaches, modified for application to beat-to-beat diastolic blood pressure and PPGa measurements. Baseline BRSc was not different between SCD and non-SCD subjects, was not correlated with BRSv, and was not associated with the vasoconstriction responses to MTS tasks. BRSv in both groups was correlated with mean PPGa, and since both baseline PPGa and BRSv were lower in SCD, these results suggested that the SCD subjects were in a basal state of higher sympathetically mediated vascular tone. In both groups, baseline BRSv was positively correlated with the vasoconstriction responses to N-back, Stroop, and PA. After adjusting for differences in BRSv within and between groups, we found no difference in the vasoconstriction responses to all three mental tasks between SCD and non-SCD subjects. The implications of these findings are significant in subjects with SCD since vasoconstriction reduces microvascular flow and prolongs capillary transit time, increasing the likelihood for vaso-occlusive crisis (VOC) to be triggered by exposure to stressful events.

A polygenic score for acute vaso-occlusive pain in pediatric sickle cell disease

Individuals with monogenic disorders can experience variable phenotypes that are influenced by genetic variation. To investigate this in sickle cell disease (SCD), we performed whole-genome sequencing (WGS) of 722 individuals with hemoglobin HbSS or HbSβ0-thalassemia from Baylor College of Medicine and from the St. Jude Children's Research Hospital Sickle Cell Clinical Research and Intervention Program (SCCRIP) longitudinal cohort study. We developed pipelines to identify genetic variants that modulate sickle hemoglobin polymerization in red blood cells and combined these with pain-associated variants to build a polygenic score (PGS) for acute vaso-occlusive pain (VOP). Overall, we interrogated the α-thalassemia deletion -α3.7 and 133 candidate single-nucleotide polymorphisms (SNPs) across 66 genes for associations with VOP in 327 SCCRIP participants followed longitudinally over 6 years. Twenty-one SNPs in 9 loci were associated with VOP, including 3 (BCL11A, MYB, and the β-like globin gene cluster) that regulate erythrocyte fetal hemoglobin (HbF) levels and 6 (COMT, TBC1D1, KCNJ6, FAAH, NR3C1, and IL1A) that were associated previously with various pain syndromes. An unweighted PGS integrating all 21 SNPs was associated with the VOP event rate (estimate, 0.35; standard error, 0.04; P = 5.9 × 10-14) and VOP event occurrence (estimate, 0.42; standard error, 0.06; P = 4.1 × 10-13). These associations were stronger than those of any single locus. Our findings provide insights into the genetic modulation of VOP in children with SCD. More generally, we demonstrate the utility of WGS for investigating genetic contributions to the variable expression of SCD-associated morbidities.

Clinical and Laboratory Predictors of Painful Vaso-Occlusive Crisis Among Sickle Cell Disease Patients: A Single-Center Study in Saudi Arabia

Introduction Vaso-occlusive crisis (VOC) episodes are considered to be the cause of 95% of hospitalizations for sickle cell disease (SCD) patients. The frequency of VOC is significantly associated with higher or lower lactate dehydrogenase levels, higher hemoglobin concentration, higher white blood cell, and neutrophil count, and lower platelet counts. In this study, we highlighted the association and predictors of VOC episodes in Saudi Arabia. Methods This is a retrospective observational study that was conducted in a period from January 2018 to December 2019 which included patients who were admitted and treated as sickle cell disease patients were included in this study. Retrieved data included patients' age, sex, and other demographic data items as well as the clinical history of SCD. The patients were divided into two groups. Those patients who developed one or two VOC episodes in the period between 2018-2019 were considered mild in severity and patients who developed three or more VOC episodes in the period between 2018-2019 were categorized as moderate to severe. Results A total of ninety-four patients (58 males and 36 females) with a male to female ratio of 1.6 were included in this study. The prevalence of patients who had severe vaso-occlusive crisis was 39.4% while mild-moderate were detected among 60.6% of the patients. It was found that there was no significant difference between the frequency of vaso-occlusive crisis and all the hematological parameters (all p>0.05). It was found that the risk of having vaso-occlusive crisis for those patients who were admitted more than three times was 30 times higher than those patients who were admitted by three times or less [adjusted odds ratio (AOR) = 30.081; 95% confidence interval (CI) = 8.204 - 110.3; p<0.001)]. Conclusion It was found that those patients who had three times VOC episodes in our studied period are more liable to have frequent episodes in the future which might necessitate urgent intervention for these patients.

Voxelotor: alteration of sickle cell disease pathophysiology by a first-in-class polymerization inhibitor

Sickle cell disease, despite its recognition as a severely debilitating genetic condition affecting hundreds of thousands of neonates throughout the world each year, was not a target of pharmaceutical research focus for most of its 100-year existence in the medical consciousness. This has changed in recent years as many novel therapeutics are currently under investigation, with three new disease-modifying drugs achieving FDA approval in the last 4 years. One of these drugs, voxelotor, is especially encouraging as an inhibitor of sickling for its ability to safely improve the chronic hemolytic anemia of sickle cell disease. This was demonstrated during all clinical phases of investigation by an average improvement in hemoglobin of greater than 1 g/dL, as well as statistically significant improvements in established markers of hemolysis. While anemia itself represents a potential cause of morbidity, it is more importantly a marker of the hemolysis known to cause the long-term vascular and organ damage that makes sickle cell disease so debilitating and frequently fatal early in life. Given the recency of the approval, there has not been sufficient long-term follow-up to demonstrate improvement in the chronic sequelae of sickle cell disease as a result of voxelotor-induced improvements in hemolytic anemia. There is hope, however, based on the experience with hydroxyurea improving morbidity and mortality via reductions in sickling and improved rheology, that voxelotor may have similar long-term benefits by positively manipulating the kinetics of hemoglobin polymerization. This review aims to summarize the targeted pathobiology of sickle cell disease, the mechanism of action of voxelotor, and the safety and efficacy data from preclinical to late clinical stage investigations of this long-awaited medication, in the hopes of better informing the decision-making process behind prescribing or not prescribing it for patients in need of intervention.

Alpha thalassemia, but not βS-globin haplotypes, influence sickle cell anemia clinical outcome in a large, single-center Brazilian cohort

Alpha thalassemia and beta-globin haplotype are considered classical genetic disease modifiers in sickle cell anemia (SCA) causing clinical heterogeneity. Nevertheless, their functional impact on SCA disease emergence and progression remains elusive. To better understand the role of alpha thalassemia and beta-globin haplotype in SCA, we performed a retrospective study evaluating the clinical manifestations of 614 patients. The univariate analysis showed that the presence of alpha-thalassemia -3.7-kb mutation (αα/-α and -α/-α) decreased the risk of stroke development (p = 0.046), priapism (p = 0.033), and cholelithiasis (p = 0.021). Furthermore, the cumulative incidence of stroke (p = 0.023) and cholelithiasis (p = 0.006) was also significantly lower for patients carrying the alpha thalassemia -3.7-kb mutation. No clinical effects were associated with the beta-globin haplotype analysis, which could be explained by the relatively homogeneous haplotype composition in our cohort. Our results reinforce that alpha thalassemia can provide protective functions against hemolysis-related symptoms in SCA. Although, several genetic modifiers can impact the inflammatory state of SCA patients, the alpha thalassemia mutation remains one of the most recurrent genetic aberration and should therefore always be considered first.

Standardized microfluidic assessment of red blood cell-mediated microcapillary occlusion: Association with clinical phenotype and hydroxyurea responsiveness in sickle cell disease

OBJECTIVES

We present a standardized in vitro microfluidic assay and Occlusion Index (OI) for the assessment of red blood cell (RBC)-mediated microcapillary occlusion and its clinical associations in sickle cell disease (SCD).

METHODS

Red blood cell mediated microcapillary occlusion represented by OI and its clinical associations were assessed for seven subjects with hemoglobin-SC disease (HbSC), 18 subjects with homozygous SCD (HbSS), and five control individuals (HbAA).

RESULTS

We identified two sub-populations with HbSS based on the OI distribution. HbSS subjects with relatively higher OIs had significantly lower hemoglobin levels, lower fetal hemoglobin (HbF) levels, and lower mean corpuscular volume (MCV), but significantly higher serum lactate dehydrogenase levels and absolute reticulocyte counts, compared to subjects with HbSS and lower OIs. HbSS subjects who had relatively higher OIs were more likely to have had a concomitant diagnosis of intrapulmonary shunting (IPS). Further, lower OI associated with hydroxyurea (HU) responsiveness in subjects with HbSS, as evidenced by significantly elevated HbF levels and MCV.

CONCLUSIONS

We demonstrated that RBC-mediated microcapillary occlusion and OI associated with subject clinical phenotype and HU responsiveness in SCD. The presented standardized microfluidic assay may be useful for evaluating clinical phenotype and assessing therapeutic outcomes in SCD, including emerging targeted and curative treatments that aim to improve RBC deformability and microcirculatory health.

Age of first pain crisis and associated complications in the CASiRe international sickle cell disease cohort

Pain is a hallmark of Sickle Cell Disease (SCD) affecting patients throughout their life; the first pain crisis may occur at any age and is often the first presentation of the disease. Universal newborn screening identifies children with SCD at birth, significantly improving morbidity and mortality. Without early screening, diagnosis is generally made after disease manifestations appear. The Consortium for the Advancement of Sickle Cell Research (CASiRe) is an international collaborative group evaluating the clinical severity of subjects with SCD using a validated questionnaire and medical chart review, standardized across 4 countries (United States, United Kingdom, Italy and Ghana). We investigated the age of first pain crisis in 555 sickle cell subjects, 344 adults and 211 children. Median age of the first crisis in the whole group was 4 years old, 5 years old among adults and 2 years old among children. Patients from the United States generally reported the first crisis earlier than Ghanaians. Experiencing the first pain crisis early in life correlated with the genotype and disease severity. Early recognition of the first pain crisis could be useful to guide counseling and management of the disease.

Polymorphisms of the receptor for advanced glycation end products as vasculopathy predictor in sickle cell disease

BACKGROUND

The genetic variants of the receptor for advanced glycation end products (RAGE) gene have been associated with vascular disease risk. The objective of this work was to explore the association of three single-nucleotide polymorphisms (SNPs) of RAGE gene (374T/A, 429T/C, and G82S) with vascular complications in SCD.

METHODS

The study was conducted on 40 children with SCD and 40 healthy children served as controls. All participants were genotyped for the three studied RAGE polymorphisms by polymerase chain reaction (PCR).

RESULTS

Regarding 374T/A polymorphism, the frequency of TA, TT genotypes and T allele were higher in patients (p < 0.001). T allele was associated with higher incidence of sickling crisis and stroke (p < 0.05). In the subgroup analyses of 429T/C polymorphism, an association between C allele and SCD vascular complications was observed (p < 0.05). Concerning the frequency of G82S genotypes of RAGE, GG variant was detected in 39 (97.5%) of the patients, as compared with 40 (100%) of controls (p = 0.3). A regression analysis proved that HbS%, serum ferritin, and the -374T and 429C alleles were significant independent predictors of frequent sickling episodes (p < 0.05).

CONCLUSIONS

The C allele of -429T/C and T allele of 374T/A RAGE polymorphisms may be considered as predictors for vascular dysfunction in SCD.

IMPACT

The C allele of -429T/C and T allele of 374T/A RAGE polymorphisms may be considered as predictors for vascular dysfunction in SCD patients. To our knowledge, our study is the first exploring the association of three single-nucleotide polymorphisms of RAGE gene (374T/A, 429T/C, and G82S) with vascular complications in SCD. Early identification of patients carrying these genetic variants might be of great importance not only to identify subjects at risk of vasculopathy but also to direct them to RAGE-targeted treatments.

An evaluation of ticagrelor for the treatment of sickle cell anemia

INTRODUCTION

Ticagrelor is an antiplatelet agent approved for the treatment of patients with an acute coronary syndrome or a history of myocardial infarction. Considering the evidence demonstrating that ticagrelor-mediated inhibition of platelet activation and aggregation have beneficial effects in the treatment of thrombotic conditions, clinical studies have been conducted to evaluate the use of this drug for the treatment of sickle cell disease (SCD), demonstrating satisfactory tolerability and safety.

AREAS COVERED

Clinical investigation has characterized the pharmacokinetic and pharmacodynamical profile, as well as the efficacy and safety of ticagrelor to prevent painful vaso-occlusive crisis (painful episodes and acute chest syndrome) in SCD patients.

EXPERT OPINION

While phase 1 and 2 clinical trials demonstrated satisfactory tolerability and safety, the conclusion of phase 3 clinical trials is crucial to prove the efficacy of ticagrelor as a therapeutic option for the treatment of SCD. Thus, it is expected that ticagrelor, especially in combination with other drugs, will improve the clinical profile and quality of life of patients with SCD.

Cost of health care for paediatric patients with sickle cell disease: An analysis of resource use and costs in a European country

BACKGROUND

While multiple studies have examined the cost of health care for one aspect of sickle cell disease care, few have focussed on the overall cost of comprehensive care for sickle cell disease.

METHODS

We conducted a retrospective cohort study of children with sickle cell disease treated in a comprehensive care centre from 1 January 2015 to 31 December 2016. Health care utilisation of included patients was based upon data from two main sources. The clinical practice guideline was used to determine the expected resource use of routine comprehensive care (planned elective care), and the financial claims database was used to estimate real-world resource use associated with acute and inpatient care (additional care).

RESULTS

A total of 125 children with sickle cell disease were analysed. Expenditures for these patients averaged €5049 [standard deviation (SD) €1634] per child per year. Total yearly costs per patient varied considerably, ranging from €669 to €84 010, and less than 15% of patients were responsible for 50% of the health care costs. The majority (37%) of costs was associated with inpatient hospital care, which increased by age group, 27% with diagnostics, 19% with treatment, 11% with outpatients' visits and 6% with emergency care.

CONCLUSION

We have described real-world resource use and expenditures for children with sickle cell disease in a European comprehensive care centre. It seems that costs of a comprehensive approach with effective management in the outpatient setting is favourable when compared to episodic health care.

A Healthcare Improvement Initiative to Increase Multidisciplinary Pain Management Referrals for Youth with Sickle Cell Disease

BACKGROUND

Chronic pain is a complex integration of biological, psychological, and social variables. Multidisciplinary pain management experts design interventions that treat the multidimensional experience. Children and adolescents with sickle cell disease (SCD) are at risk for chronic pain. Increased risk is associated with multiple characteristics including sickle cell genotype, age, gender, frequency of hospitalization, duration of hospitalization, and certain comorbid diagnoses. Referral to pain management professionals for this population is often delayed.

AIMS

To increase multidisciplinary pain management referrals for youth with SCD identified to be at risk for chronic pain.

DESIGN

Implementation research.

SETTING

One pediatric, academic medical facility serving as a regional sickle cell treatment center in the Midwest.

PARTICIPANTS

Children greater than 2 years of age and less than 21 years of age with laboratory confirmed SCD.

METHODS

Implementation of an evidence-based screening tool using the consolidated framework for implementation research (CFIR) to guide project planning, design, and evaluation. The CFIR model was paired with the Plan-Do-Study-Act (PDSA) quality improvement methodology to operationalize workflow and sustain project aims.

RESULTS AND CONCLUSIONS

Eighty-four percent of all eligible patients were screened during their routine sickle cell appointments resulting in a 110% increase in multidisciplinary pain management referrals. Future interventions and PDSA cycles are targeted at improving attendance at scheduled appointments, reducing hospitalizations, decreasing 30-day readmissions, and shortening length of stay.

Review/overview of pain in sickle cell disease

Sickle cell disease (SCD) is a highly complex inherited disorder of hemoglobin structure. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of the disease. Its manifestations could be acute, chronic, nociceptive, neuropathic that could occur singly or in various combinations. Pain continues to be the major factor of SCD phenotypic complications and the most common cause of admissions to the Emergency Department and/or the hospital. Although progress has been made in understanding the pathophysiology of SCD as well as in developing curative therapies such as hematopoietic stem cell transplantation and gene therapy, effective pain management continues to lag behind. Palliative therapies continue to be the major approach to the management of SCD and its complications. The advent of hydroxyurea made partial success in preventing the frequency of vaso-occlusive crises and l-glutamine awaits post-trial confirmation of benefits. The search for additional pharmacotherapeutic agents that could be used singly or in combination with hydroxyurea and/or l-glutamine awaits their dawn hopefully in the near future. The purpose of this review is to describe the various manifestations of SCD, their pathophysiology and their current management. Recent impressive advances in understanding the pathophysiology of pain promise the determination of agents that could replace or minimize the use of opioids.

Physical Activity and Pain in Youth With Sickle Cell Disease

Study objectives were to examine the relationships between physical activity, pain, and psychological distress in youth 8 to 17 years of age with sickle cell disease. Participants were 206 youth with sickle cell disease (M = 11.73 years, 54.9% female, 99.5% African American). Caregivers and youth completed a clinical psychosocial screening battery. Results revealed frequent pain (37.6%), moderate median pain intensity, and elevated median pain interference in youth. Lower caregiver-reported physical activity was associated with worse pain outcomes. Increased anxiety was also associated with worse pain outcomes. A better understanding of the relationship between physical activity/inactivity and pain will guide multifactorial treatment interventions.

End points for sickle cell disease clinical trials: patient-reported outcomes, pain, and the brain

To address the global burden of sickle cell disease (SCD) and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to: patient-reported outcomes (PROs), pain (non-PROs), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the PROs, pain, and brain panels, as well as relevant findings and recommendations from the biomarkers panel. The panels identify end points, where there were supporting data, to use in clinical trials of SCD. In addition, the panels discuss where further research is needed to support the development and validation of additional clinical trial end points.

Correlates of successful transition in young adults with sickle cell disease

The transition period from pediatric care to adult care for patients with sickle cell disease (SCD) is associated with increased mortality and morbidity. Identification of risk factors for unsuccessful transition may aid in developing strategies to improve the transition process and health outcomes in this population. We examined factors associated with unsuccessful transition from pediatric to adult care for patients with SCD at the Johns Hopkins Hospital. We found that public insurance and increased hospitalization rates were associated with poor transition to adult care. The findings provide possible areas of intervention.

Sickle cell disease subjects and mouse models have elevated nitrite and cGMP levels in blood compartments

The hypothesis of decreased nitric oxide (NO) bioavailability in sickle cell disease (SCD) proposes that multiple factors leading to decreased NO production and increased consumption contributes to vaso-occlusion, pulmonary hypertension, and pain. The anion nitrite is central to NO physiology as it is an end product of NO metabolism and serves as a reservoir for NO formation. However, there is little data on nitrite levels in SCD patients and its relationship to pain phenotype. We measured nitrite in SCD subjects and examined its relationship to SCD pain. In SCD subjects, median whole blood, red blood cell and plasma nitrite levels were higher than in controls, and were not associated with pain burden. Similarly, Townes and BERK homozygous SCD mice had elevated blood nitrite. Additionally, in red blood cells and plasma from SCD subjects and in blood and kidney from Townes homozygous mice, levels of cyclic guanosine monophosphate (cGMP) were higher compared to controls. In vitro, hemoglobin concentration, rather than sickle hemoglobin, was responsible for nitrite metabolism rate. In vivo, inhibition of NO synthases and xanthine oxidoreductase decreased nitrite levels in homozygotes but not in control mice. Long-term nitrite treatment in SCD mice further elevated blood nitrite and cGMP, worsened anemia, decreased platelets, and did not change pain response. These data suggest that SCD in humans and animals is associated with increased nitrite/NO availability, which is unrelated to pain phenotype. These findings might explain why multiple clinical trials aimed at increasing NO availability in SCD patients failed to improve pain outcomes.

Combined and differential effects of alpha-thalassemia and HbF-quantitative trait loci in Senegalese hydroxyurea-free children with sickle cell anemia

BACKGROUND

Our objective was to investigate the combined and differential effects of alpha-thalassemia -3.7 kb deletion and HbF-promoting quantitative trait loci (HbF-QTL) in Senegalese hydroxyurea (HU)-free children and young adults with sickle cell anemia (SCA).

PROCEDURE

Steady-state biological parameters and vaso-occlusive crises (VOC) requiring emergency admission were recorded over a 2-year period in 301 children with SCA. The age of the first hospitalized VOC was also recorded. These data were correlated with the alpha-globin and HbF-QTL genotypes. For the latter, three different genetic loci were studied (XmnI, rs7482144; BCL11A, rs1427407; and the HBS1L-MYB region, rs28384513) and a composite score was calculated, ranging from zero (none of these three polymorphisms) to six (all three polymorphisms at the homozygous state).

RESULTS

A positive clinical impact of the HbF-QTL score on VOC rate, HbF, leucocytes, and C-reactive protein levels was observed only for patients without alpha-thalassemia deletion. Conversely, combination of homozygous -3.7 kb deletion with three to six HbF-QTL was associated with a higher VOC rate. The age of the first hospitalized VOC was delayed for patients with one or two alpha-thalassemia deletions and at least two HbF-QTL.

CONCLUSION

Alpha-thalassemia -3.7 kb deletion and HbF-QTL are modulating factors of SCA clinical severity that interact with each other. They should be studied and interpreted together and not separately, at least in HU-free children.

Angiopoietin-2 as a Marker of Retinopathy in Children and Adolescents With Sickle Cell Disease: Relation to Subclinical Atherosclerosis

OBJECTIVES

Angiopoietin-2 (Ang-2) is a multifaceted cytokine that functions in both angiogenesis and inflammation. A proangiogenic state has been found in adults with sickle cell disease (SCD), mainly because of elevated Ang-2 levels. We determined Ang-2 level in 40 children and adolescents with SCD compared with 40 healthy controls and assessed its relation to retinopathy as well as carotid intimamedia thickness (CIMT).

METHODS

Hematologic profile, serum ferritin, and serum Ang-2 were measured. CIMT was assessed using high-resolution ultrasound. Fundus examination was performed followed by fundus fluorescein angiography. Optical coherence tomography angiography (OCTA) was used to find small vascular changes not clinically manifested.

RESULTS

Ang-2 levels and CIMT were significantly higher in SCD patients compared with controls. The incidence of nonproliferative retinopathy was 45%. SCD patients with retinopathy were older in age with a history of sickling crisis of >3 attacks per year and had a higher incidence of sickle cell anemia than sickle β-thalassemia. Ang-2 cutoff value 9000 pg/mL could significantly detect the presence of retinopathy among SCD patients with 100% sensitivity and specificity. Serum Ang-2 levels were positively correlated with HbS and CIMT. Logistic regression analysis revealed that Ang-2 and HbS significantly contribute to retinopathy among patients with SCD.

CONCLUSIONS

Elevated Ang-2 highlights the role of angiogenesis in the pathophysiology of SCD and may be considered a promising marker for screening of patients at risk of sickle retinopathy and vascular dysfunction.

Elevated tricuspid regurgitation velocity in congenital hemolytic anemias: Prevalence and laboratory correlates

Elevated tricuspid valve regurgitation jet velocity (TRV ≥ 2.5 m/s) is associated with mortality among adults with sickle cell disease (SCD), but correlative biomarkers are not studied according to treatment exposure or genotypes. To investigate the associations between biomarkers and TRV elevation, we examined the relationship between TRV and hemolytic, inflammatory, and cardiac biomarkers, stratified by disease-modifying treatments and SCD genotype. In total, 294 participants with SCD (mean age, 11.0 ± 3.7 years) and 49 hereditary spherocytosis (HS; mean age, 22.9 ± 19.75 years) were included for comparison and enrolled. TRV was elevated in 30.7% of children with SCD overall: 18.8% in HbSC/HbSβ⁺ -thalassemia, 28.9% in untreated HbSS/HbSβ⁰ -thalassemia, 34.2% in HbSS/HbSβ⁰ -thalassemia hydroxyurea-treated, and 57% in HbSS/HbSβ⁰ -thalassemia chronic transfusion treated. TRV was elevated in 10.7% and 27.8% in HS children and adults, respectively. In children with SCD, elevated TRV was correlated with hemoglobin (odds ratio [OR] = 0.78, P = 0.004), lactate dehydrogenase (LDH; OR = 2.52, P = 0.005), and N-terminal pro-brain natriuretic peptide (NT-pro BNP; OR = 1.003, P = 0.004). In multivariable logistic regression, adjusting for genotype, sex, hemolytic index, and treatment, hemoglobin concentration remained the only significant variable associated with elevated TRV in untreated HbSS/HbSβ⁰ -thalassemia participants. TRV was not associated with inflammatory markers, other markers of hemolysis, or NT-pro BNP in untreated HbSS/HbSβ⁰ -thalassemia. Neither hemoglobin nor LDH was associated with TRV in HbSC/HbSβ⁺ -thalassemia. These results suggest that elevated TRV is influenced by the degree of anemia, possibly reflecting sickling as part of the disease pathophysiology. Prospective studies should monitor hemoglobin concentration as children with SCD age into adulthood, prompting initiation of TRV screening and monitoring.

Immunological role of CD4+CD28null T lymphocytes, natural killer cells, and interferon-gamma in pediatric patients with sickle cell disease: relation to disease severity and response to therapy

Sickle cell disease (SCD) is associated with alterations in immune phenotypes. CD4⁺CD28^null T lymphocytes have pro-inflammatory functions and are linked to vascular diseases. To assess the percentage of CD4⁺CD28^null T lymphocytes, natural killer cells (NK), and IFN-gamma levels, we compared 40 children and adolescents with SCD with 40 healthy controls and evaluated their relation to disease severity and response to therapy. Patients with SCD steady state were studied, focusing on history of frequent vaso-occlusive crisis, hydroxyurea therapy, and IFN-gamma levels. Analysis of CD4⁺CD28^null T lymphocytes and NK cells was done by flow cytometry. Liver and cardiac iron overload were assessed. CD4⁺CD28^null T lymphocytes, NK cells, and IFN-gamma levels were significantly higher in patients than controls. Patients with history of frequent vaso-occlusive crisis and those with vascular complications had higher percentage of CD4⁺CD28^null T lymphocytes and IFN-gamma while levels were significantly lower among hydroxyurea-treated patients. CD4⁺CD28^null T lymphocytes were positively correlated to transfusional iron input while these cells and IFN-gamma were negatively correlated to cardiac T2* and duration of hydroxyurea therapy. NK cells were correlated to HbS and indirect bilirubin. Increased expression of CD4⁺CD28^null T lymphocytes highlights their role in immune dysfunction and pathophysiology of SCD complications.

Surfactant protein D as a marker for pulmonary complications in pediatric patients with sickle cell disease: Relation to lung function tests

BACKGROUND

Surfactant protein D (SP-D) is considered a candidate biomarker for lung integrity and for disease progression.

AIM

We determined the level of SP-D in children and adolescents with SCD and assessed its possible relation to pulmonary complications and lung function.

METHODS

Serum SP-D levels were assessed in 50 SCD patients compared with 30 healthy controls. High-resolution computerized tomography (HRCT) of the chest was done. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁ ), FEV₁ /FVC% and forced expiratory flow rate during 25-75% of expiration (FEF25-75%) were determined.

RESULTS

SP-D was significantly higher in SCD patients than controls, particularly patients with sickle cell anemia than those with sickle β-thalassemia. SP-D levels were significantly associated with increasing severity of interstitial lung disease. The highest SP-D levels were observed among patients with restrictive lung disease followed by mixed type then obstructive lung disease. SP-D was positively correlated to HbS and serum ferritin while negatively correlated to duration of hydroxyurea treatment and parameters of pulmonary functions. ROC curve analysis revealed that SP-D cutoff value 720 ng/mL could significantly detect the presence of abnormal pulmonary function among SCD patients with 82% sensitivity and 88% specificity. Logistic regression analysis showed that SP-D is an independent factor related to abnormal pulmonary function in SCD.

CONCLUSIONS

SP-D may be a promising biomarker for screening of SCD patients for risk of later pulmonary complications.

Virtual reality as complementary pain therapy in hospitalized patients with sickle cell disease

OBJECTIVE

Due to incomplete management of vaso-occlusive pain episodes (VOE) in patients with sickle cell disease (SCD), we sought to determine if immersive VR would be feasible for inpatients. Secondarily, we hypothesized that a single VR session would improve the VOE pain experience.

PROCEDURES

Consecutive patients with SCD eight years and older admitted for VOE were offered one 15-minute VR session, utilizing a relaxing underwater world specifically created for pediatric patients and to minimize potential simulator side effects. Safety and acceptability were evaluated with a brief survey before and after the session. Pain was evaluated utilizing the validated adolescent pediatric pain tool (APPT). Survey data and pain scores were analyzed using Wilcoxon signed-rank test as the data were nonnormally distributed.

RESULTS

Thirty patients, 21 female, with a median age of 16 years were enrolled, the majority having hemoglobin SS disease. The VR session had no reported side effects; all patients requested VR again in the future. Median pain intensity (pre-VR 7.3 [interquartile range, IQR, 6.1, 8.8], post-VR 5.8 [4.7, 7.9]), number of affected body areas (pre-VR 3.0 [2.0, 7.8], post-VR 2.0 [0, 4.8]), and qualitative measures including sensory, affective, evaluative, and temporal pain domains were all statistically reduced (i.e., P ≤0.01).

CONCLUSIONS

VR therapy was feasible in a cohort of patients with SCD admitted for VOE. In addition to standard therapies, VR may help reduce the pain experience with SCD VOE. Further study is required to determine the impact of VR therapy on opioid usage and length of stay in hospital.

Transition to adult care in sickle cell disease: A longitudinal study of clinical characteristics and disease severity

BACKGROUND

Sickle cell disease (SCD) is a chronic blood disorder in which mortality has increased for adolescents and young adults (AYA).

PROCEDURE

A longitudinal analysis of medical records was conducted to describe the clinical course among AYAs (ages 12-27 years) during transition to adult care. Measures included sociodemographic, complications, SCD severity (modified pediatric SCD severity index), comorbidities, and transfer. Group-based trajectory modeling (GBTM) to identify subgroups with distinct severity trajectories and chi-square and unpaired Student t test to explore subgroup differences were used.

RESULTS

Overall, 339 AYAs (97% black, 56% male, 69% hemoglobin SS) had 10 848 clinic, 3840 hospital, and 3152 emergency department visits. Complications included vaso-occlusive crises (80%) and acute chest syndrome (41%). Comorbidities included depression (19%) and anxiety (14%). Most AYAs transferred to adult care (n = 220) at 19 years. Fourteen AYAs died, 10 within seven years from transfer. GBTM identified both stable and increasing severity trajectory groups: stable-low (n = 31, 23%), stable-medium (n = 61, 46%), stable-high (n = 6, 4.5%), low-increasing (n = 13, 10%), and medium-increasing (n = 22, 17%). AYAs with increasing severity (25%) were older, lived closer to the clinic, and had higher risk for SCD complications and comorbidities. They had fewer pediatric clinic visits; however, they were more likely to transfer and remain longer in adult SCD care.

CONCLUSIONS

Whereas most AYAs had stable severity, nearly a quarter had increasing severity, over time. AYAs with increasing severity had more complications, were more likely to transfer to adult care, and demonstrated higher and longer adult SCD care utilization compared with AYAs with stable severity.

AAAPT Diagnostic Criteria for Acute Sickle Cell Disease Pain

Acute pain episodes are the most common complication in patients with sickle cell disease (SCD). Classically attributed to vaso-occlusion, recent insights suggest that chronic pain may also contribute to the pathogenesis of acute pain episodes, which adds complexity to their diagnosis and management. A taxonomy, or classification system, for acute pain in patients with SCD would aid research efforts and enhance clinical care. To meet this need, the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks public-private partnership with the U.S. Food and Drug Administration, the American Pain Society, and the American Academy of Pain Medicine formed the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks-American Pain Society-American Academy of Pain Medicine Pain Taxonomy initiative. One of the goals of this initiative was to develop taxonomies for acute pain disorders, including SCD. To accomplish this, a working group of experts in SCD and pain was convened. Based on available literature and expert opinion, the working group used a 5-dimenional structure (diagnostic criteria, common features, modulating factors, impact/functional consequences, and putative mechanisms) to develop an acute pain taxonomy that is specific to SCD. As part of this, a set of 4 diagnostic criteria, with 2 modifiers to account for the influence of chronic pain, are proposed to define the types of acute pain observed in patients with SCD. PERSPECTIVE: This article presents a taxonomy for acute pain in patients with SCD. This taxonomy could help to standardize definitions of acute pain in clinical studies of patients with SCD.

Rheological properties of sickle erythrocytes in patients with sickle-cell anemia: The effect of hydroxyurea, fetal hemoglobin, and α-thalassemia

OBJECTIVE

Determine the effect of fetal hemoglobin (HbF) and α-thalassemia on red blood cell (RBC) deformability of patients with sickle-cell anemia (SCA) with and without hydroxyurea (HU).

METHODS

Adult patients were enrolled in the Sickle Cell Program of the Cardeza Foundation (Thomas Jefferson University) and were followed up prospectively during the period in which the Multicenter Study of Hydroxyurea (MSH) in patients with SCA was conducted. Ninety-one patients did not receive HU, 20 patients were enrolled in MSH, and 10 patients were enrolled in an open-label study of HU in SCA. Of the 20 patients enrolled in MSH, 11 took HU and nine took placebo. Control group included 113 normal individuals. Red blood cell deformability index (DI) was measured by ektacytometry.

RESULTS

Patients with SCA taking HU (n = 21) had higher DI than those taking placebo (n = 9) or who were not taking this therapy (n = 91). In patients without therapy, those with α-thalassemia (n = 31) had higher DI than those without. We showed a significant positive correlation between the level of HbF and DI. SCA patients without α-thalassemia and HbF <10% (n = 48) had lower DI than patients with α-thalassemia and HbF <10% (n = 23) and patients with (n = 8) or without α-thalassemia but with HbF >10% (n = 12). DI measured in patients without α-thalassemia and HbF >10% was higher than in the three other subgroups.

CONCLUSION

Elevated levels of HbF with or without HU and α-thalassemia improve sickle RBC rheology, which, in turn, improve the clinical picture of SCA.

Soluble receptor for advanced glycation end products as a vasculopathy biomarker in sickle cell disease

BACKGROUND

Soluble forms of RAGE (sRAGE) have been found circulating in plasma and tissues. Evidence is accruing in human subjects linking levels of sRAGE to oxidative stress in many disorders. Because sickle cell disease (SCD) is a state of oxidative stress, we tested the hypothesis that circulating sRAGE levels may be involved in the vascular pathology of SCD.

OBJECTIVES

To determine the sRAGE levels in children and adolescents with SCD and investigate their association with markers of hemolysis, iron overload, and SCD-related organ complications.

SUBJECTS AND METHODS

The level of sRAGE was measured in 40 children and adolescent with SCD compared with 40 healthy controls using enzyme-linked immunosorbent assay (ELISA).

RESULTS

sRAGE was significantly higher in patients compared with controls (p < 0.001) and was elevated in patients with history of stroke, acute lung syndrome, and frequency of sickling crisis or serum ferritin > 2500 (p < 0.05). Patients with high sRAGE levels are candidates for chelation. sRAGE was positively correlated with HbS% (r = 0.422, p = 0.007), LDH (r = 0.329, p = 0.038), and serum ferritin levels (r = 0.516, p = 0.001). Multivariable regression analysis proved that both HbS% and serum ferritin were significant independent factors affecting sRAGE level (p < 0.05).

CONCLUSION

Our findings suggest that sRAGE may be considered as a marker for vascular dysfunction in SCD patients.

Impact of early analgesia on hospitalization outcomes for sickle cell pain crisis

BACKGROUND

Painful events are the leading cause of hospitalizations for patients with sickle cell disease. Individualized pain plans targeting patient-specific maximum opioid dosing may shorten hospitalization length and are recommended by national guidelines. Prior to implementing individualized sickle cell pain plans, we tested the hypothesis that a shorter time to achieve a maximum opioid dose would improve hospitalization outcomes.

PROCEDURE

Two-year IRB-approved, retrospective study of pediatric patients admitted for vaso-occlusive crisis (VOC). We recorded the emergency department admission time, order entry time for the maximum opioid dose during the hospitalization, and time of discharge orders.  We categorized patients as infrequent if they required <3 admissions for VOC over two years and patients as frequent if they required ≥3 admissions for VOC over two years. To account for multiple admissions, generalized linear modeling was performed.

RESULTS

We identified 236 admissions for acute pain observed in 108 patients. Achieving an earlier maximum opioid dose was significantly associated with shorter length of hospitalization for frequent and infrequent pain patients (both P ≤ 0.0001). As total hospitalization length can be impacted by the time a maximum opioid order was placed, we also analyzed hospitalization length after the maximum opioid order was placed. Frequent pain patients who achieved earlier analgesia had a significantly shorter hospitalization from the time the maximum opioid order was placed (P = 0.03) while no association was found for infrequent pain patients (P = 0.84).

CONCLUSIONS

Early achievement of maximum analgesia improved hospitalization outcomes and warrant further investigation in prospective studies of individualized pain plans.

Graph theory analysis reveals how sickle cell disease impacts neural networks of patients with more severe disease

Sickle cell disease (SCD) is a hereditary blood disorder associated with many life-threatening comorbidities including cerebral stroke and chronic pain. The long-term effects of this disease may therefore affect the global brain network which is not clearly understood. We performed graph theory analysis of functional networks using non-invasive fMRI and high resolution EEG on thirty-one SCD patients and sixteen healthy controls. Resting state data were analyzed to determine differences between controls and patients with less severe and more severe sickle cell related pain. fMRI results showed that patients with higher pain severity had lower clustering coefficients and local efficiency. The neural network of the more severe patient group behaved like a random network when performing a targeted attack network analysis. EEG results showed the beta1 band had similar results to fMRI resting state data. Our data show that SCD affects the brain on a global level and that graph theory analysis can differentiate between patients with different levels of pain severity.

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Graph theory used to study global impact of long term sickle cell disease on brain.

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EEG and fMRI results compared to study spatial and temporal impact of disease.

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More severe patients have less clustering and efficiency.

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Small world values correlated with past hospitalizations, linking results to pain.

Genetic variants of GCH1 associate with chronic and acute crisis pain in African Americans with sickle cell disease

The multidimensional nature of pain in sickle cell disease (SCD) has rendered its therapeutic management extremely challenging. In this study, we explored the role of five single nucleotide polymorphisms (SNPs) of candidate gene GCH1 in SCD pain. Composite pain index (CPI) scores and acute care utilization rates were used as phenotype markers. Rs8007267 was associated with chronic pain (additive model: B = -3.76, p = 0.037; dominant model: B = -5.61, p = 0.021) and rs3783641 (additive model: incident rate ratio [IRR] = 1.37, p = 0.024; recessive model: IRR = 1.81, p = 0.018) with utilization rate. These associations persisted when subjects with HbSS and HbSβ° genotype only were analyzed. We also identified two haploblocks (rs10483639[G>C]-rs752688[C>T]-rs4411417[T>C] and rs3783641[T>A]-rs8007267[T>C]) with SNPs in high linkage disequilibrium. Of these, haplotype T-C of haploblock rs3783641-rs8007267 showed significant association with rate of utilization (odds ratio [OR] = 0.31, p = 0.001). Our study indicates potential contribution of GCH1 polymorphisms to the variability of pain in African Americans with SCD.

Red Blood Cell Adhesion to Heme-Activated Endothelial Cells Reflects Clinical Phenotype in Sickle Cell Disease

In sickle cell disease (SCD), 'disease severity' associates with increased RBC adhesion to quiescent endothelium, but the impact on activated endothelium is not known. Increased concentrations of free heme result from intravascular hemolysis in SCD. Heme is essential for aerobic metabolism, and plays an important role in numerous biological processes. Excess free heme induces reactive oxygen species generation and endothelial activation, which are associated with cardiovascular disorders including atherosclerosis, hypertension, and thrombosis. Here, we utilized an endothelialized microfluidic platform (Endothelium-on-a-chip) to assess adhesion of sickle hemoglobin-containing red blood cells (HbS RBCs), from adults with homozygous SCD, to heme-activated human endothelial cells (EC) in vitro. Confluent EC monolayers in microchannels were treated with pathophysiologically relevant levels of heme in order to simulate the highly hemolytic intravascular milieu seen in SCD. RBC adhesion to heme-activated ECs varied from subject to subject, and was associated with plasma markers of hemolysis (LDH) and reticulocytosis, thereby linking those RBCs that are most likely to adhere with those that are most likely to hemolyze. These results re-emphasize the critical contribution made by heterogeneous adhesive HbS RBCs to the pathophysiology of SCD. We found that adhesion of HbS RBCs to heme-activated ECs varied amongst individuals in the study population, and associated with biomarkers of hemolysis and inflammation, age, and a recent history of transfusion. Importantly, the microfluidic approach described herein holds promise as a clinically feasible Endothelium-on-a-chip platform with which to study complex heterocellular adhesive interactions in SCD. This article is protected by copyright. All rights reserved.

Red cell transfusion in paediatric patients with thalassaemia and sickle cell disease: Current status, challenges and perspectives

Notwithstanding the high safety level of the currently available blood for transfusion and the decreasing frequency of transfusion-related complications, administration of labile blood products to paediatric patients still poses unique challenges and considerations. The incidence of thalassaemia and sickle cell disease in the paediatric population may be high enough under specific racial and geographical contexts. Red cell transfusion is the cornerstone of β-thalassaemia treatment and one of the most effective ways to prevent or correct specific acute and chronic complications of sickle cell disease. However, this life-saving strategy comes with its own complications, such as additional iron overload, alloimmunization and haemolytic reactions, among others. In paediatrics, the dependency of the transfusion outcome upon disease and other recipient characteristics is more prominent compared with the adults, owing to differences in developmental maturity and physiology that render them more susceptible to common risks, exacerbate the host response to transfused cells, and modify the type or the clinical severity of the transfusion-related morbidity. The adverse branch of red cell transfusion is likely the overall effect of several factors acting synergistically to shape the clinical phenotype of this therapy, including inherent donor/blood unit variables, like antigenicity, red cell deformability and extracellular vesicles, as well as recipient variables, such as history of alloimmunization and inflammation level at time of transfusion. This review focuses on paediatric patients with β-thalassaemia and sickle cell disease as a recipient group with distinct transfusion-related characteristics, and introduces new concepts for consideration, not adequately studied and elucidated so far.

Increased theta band EEG power in sickle cell disease patients

Objective

Pain is a major issue in the care of patients with sickle cell disease (SCD). The mechanisms behind pain and the best way to treat it are not well understood. We studied how electroencephalography (EEG) is altered in SCD patients.

Methods

We recruited 20 SCD patients and compared their resting state EEG to that of 14 healthy controls. EEG power was found across frequency bands using Welch's method. Electrophysiological source imaging was assessed for each frequency band using the eLORETA algorithm.

Results

SCD patients had increased theta power and decreased beta2 power compared to controls. Source localization revealed that areas of greater theta band activity were in areas related to pain processing. Imaging parameters were significantly correlated to emergency department visits, which indicate disease severity and chronic pain intensity.

Conclusion

The present results support the pain mechanism referred to as thalamocortical dysrhythmia. This mechanism causes increased theta power in patients.

Significance

Our findings show that EEG can be used to quantitatively evaluate differences between controls and SCD patients. Our results show the potential of EEG to differentiate between different levels of pain in an unbiased setting, where specific frequency bands could be used as biomarkers for chronic pain.

Clinical and genetic factors are associated with pain and hospitalisation rates in sickle cell anaemia in Cameroon

We aimed to investigate the clinical and genetic predictors of painful vaso-occlusive crises (VOC) in sickle cell disease (SCD) in Cameroon. Socio-demographics, clinical variables/events and haematological indices were acquired. Genotyping was performed for 40 variants in 17 pain-related genes, three fetal haemoglobin (HbF)-promoting loci, two kidney dysfunctions-related genes, and HBA1/HBA2 genes. Statistical models using regression frameworks were performed in R^® . A total of 436 hydoxycarbamide- and opioid-naïve patients were studied; median age was 16 years. Female sex, body mass index, Hb/HbF, blood transfusions, leucocytosis and consultation or hospitalisation rates significantly correlated with VOC. Three pain-related genes variants correlated with VOC (CACNA2D3-rs6777055, P = 0·025; DRD2-rs4274224, P = 0·037; KCNS1-rs734784, P = 0·01). Five pain-related genes variants correlated with hospitalisation/consultation rates. (COMT-rs6269, P = 0·027; FAAH-rs4141964, P = 0·003; OPRM1-rs1799971, P = 0·031; ADRB2-rs1042713; P < 0·001; UGT2B7-rs7438135, P = 0·037). The 3·7 kb HBA1/HBA2 deletion correlated with increased VOC (P = 0·002). HbF-promoting loci variants correlated with decreased hospitalisation (BCL11A-rs4671393, P = 0·026; HBS1L-MYB-rs28384513, P = 0·01). APOL1 G1/G2 correlated with increased hospitalisation (P = 0·048). This first study from Africa has provided evidence supporting possible development of genetic risk model for pain in SCD.

Central sensitization associated with low fetal hemoglobin levels in adults with sickle cell anemia

BACKGROUND AND AIMS

Pain is the hallmark of sickle cell anemia (SCA), presenting as recurrent acute events or chronic pain. Central sensitization, or enhanced excitability of the central nervous system, alters pain processing and contributes to the maintenance of chronic pain. Individuals with SCA demonstrate enhanced sensitivity to painful stimuli however central mechanisms of pain have not been fully explored. We hypothesized that adults with SCA would show evidence of central sensitization as observed in other diseases of chronic pain.

METHODS

We conducted a prospective study of static and dynamic quantitative sensory tests in 30 adults with SCA and 30 matched controls.

RESULTS

Static thermal testing using cold stimuli showed lower pain thresholds (p=0.04) and tolerance (p=0.04) in sickle cell subjects, but not for heat. However, SCA subjects reported higher pain ratings with random heat pulses (p<0.0001) and change in scores with temporal summation at the heat pain threshold (p=0.002). Similarly, with the use of pressure pain stimuli, sickle cell subjects reported higher pain ratings (p=0.04), but not higher pressure pain tolerance/thresholds or allodynia to light tactile stimuli. Temporal summation pain score changes using 2 pinprick probes (256 and 512mN) were significantly greater (p=0.004 and p=0.008) with sickle cell, and delayed recovery was associated with lower fetal hemoglobin (p=0.002 and 0.003).

CONCLUSIONS

Exaggerated temporal summation responses provide evidence of central sensitization in SCA.

IMPLICATIONS

The association with fetal hemoglobin suggests this known SCA modifier may have a therapeutic role in modulating central sensitization.

Hypoxia-enhanced adhesion of red blood cells in microscale flow

OBJECTIVES

The advancement of microfluidic technology has facilitated the simulation of physiological conditions of the microcirculation, such as oxygen tension, fluid flow, and shear stress in these devices. Here, we present a micro-gas exchanger integrated with microfluidics to study RBC adhesion under hypoxic flow conditions mimicking postcapillary venules.

METHODS

We simulated a range of physiological conditions and explored RBC adhesion to endothelial or subendothelial components (FN or LN). Blood samples were injected into microchannels at normoxic or hypoxic physiological flow conditions. Quantitative evaluation of RBC adhesion was performed on 35 subjects with homozygous SCD.

RESULTS

Significant heterogeneity in RBC adherence response to hypoxia was seen among SCD patients. RBCs from a HEA population showed a significantly greater increase in adhesion compared to RBCs from a HNA population, for both FN and LN.

CONCLUSIONS

The approach presented here enabled the control of oxygen tension in blood during microscale flow and the quantification of RBC adhesion in a cost-efficient and patient-specific manner. We identified a unique patient population in which RBCs showed enhanced adhesion in hypoxia in vitro. Clinical correlates suggest a more severe clinical phenotype in this subgroup.

Variability of homozygous sickle cell disease: The role of alpha and beta globin chain variation and other factors

The single base molecular substitution characterizing sickle cell haemoglobin, β⁶glu→val, might be expected to result in predictable haematological and clinical features. However, the disease manifests remarkable diversity believed to reflect the interaction with other genetic and environmental factors. Some of the genetic modifiers include the beta globin haplotypes, alpha thalassaemia, factors influencing the persistence of fetal haemoglobin and the effects of the environment are addressed in this review. It is concluded that much of the genetic data present conflicting results. Environmental factors such as climate and infections, and psychological, educational and social support mechanisms also influence expression of the disease. These interactions illustrate how the expression of a 'single gene' disorder may be influenced by a variety of other genetic and environmental factors.

Clinical and Laboratory Predictors of Frequency of Painful Crises among Sickle Cell Anaemia Patients in Nigeria

INTRODUCTION

The severity of Sickle Cell Anaemia (SCA) in terms of frequency of painful Vaso-Occlusive Crises (VOC) may be affected by clinical and haematological parameters amongst others. Elucidation of these factors in a given disease prevalent environment is necessary for prompt and effective management of patients with frequent painful VOC.

AIM

This study aimed at determining the clinical and laboratory predictors of frequency of painful VOC among SCA patients in Enugu, Southeastern Nigeria.

MATERIALS AND METHODS

It was a cross-sectional study of 100 consecutive SCA patients receiving care at the University of Nigeria Teaching Hospital, Enugu, Nigeria between May 2012 and February 2014. The eligible patients were categorized into two groups namely; Group A and Group B. Group A/study group (severe disease) comprised SCA patients who had experienced three or more painful crises (≥3 crises) in the last one year preceding the study but, currently in steady state, while Group B/control group (mild-moderate disease), comprised SCA patients matched for age, sex, highest educational status, and occupation but who have had no painful crisis or had only one or two painful crises (0-2 crises) in the last one year preceding the study and currently in steady state.

RESULTS

The overall mean age of the patients was 18.4±12.2 (range=2-52) years. The mean values of the haematological parameters including haemoglobin concentration, white cell count, platelet count, and neutrophil count were significantly higher in those with severe crises than mild-moderate crises (p<0.05). Sickle cell related complications including Avascular Necrosis (AVN) and leg ulcers were significantly higher in the study group than the control group (p<0.05).

CONCLUSION

There was significant association between the frequency of crises and haemogblobin level, platelet and neutrophil counts and some clinical parameters: AVN, nephropathy and stroke. Future preventive interventions for reduction in frequency of crisis amongst patients with SCA could be targeted at controlling the blood levels of the identified haematological parameters.

Body Mass Index and the Association With Vaso-occlusive Crises in Pediatric Sickle Cell Disease

BACKGROUND

Children with sickle cell disease (SCD) historically have been underweight and have poor overall growth. Recent studies have demonstrated a trend toward obesity in pediatric SCD populations.

MATERIALS AND METHODS

Through retrospective chart review of patients with SCD followed at our center, we collected patient's data, including body mass index (BMI), weight percentiles, sickle cell genotype, baseline hemoglobin, medical and psychiatric comorbidities, 25-hydroxy vitamin D level, treatment with hydroxyurea, and chronic transfusions. We identified hospitalizations to St. Christopher's Hospital for vaso-occlusive crisis (VOC) and duration of hospitalization and intravenous opioid use were recorded. Student t test, Mann-Whitney U test, and analysis of variance were used to examine associations between variables and frequency and duration of hospitalizations for VOC.

RESULTS

Among 328 patients with SCD, overweight and obese children constituted 19% of hospitalized and nonhospitalized patients. BMI status did not influence frequency (P=0.90) or duration of hospitalization (P=0.65) for VOC. Obesity was more associated with HbSC than HbSS (P=0.025) genotype.

CONCLUSIONS

Our study did not demonstrate an association between extremes of BMI of patients and hospitalization for VOC. Considering current trend toward obesity, further prospective and interventional research are required to define the effects of extremes of BMI on pain crises in SCD.