Acute Chest Syndrome in Children with Sickle Cell Disease

SNAP: Supportive noninvasive ventilation for acute chest syndrome prevention in children with sickle cell disease

BACKGROUND

Acute chest syndrome (ACS) is a leading cause of morbidity and mortality among children with sickle cell disease (SCD). Preventing hypoxemia by optimizing lung aeration during sleep remains a challenge.

OBJECTIVES

To explore safety, feasibility, and tolerability of noninvasive, bi-level positive airway pressure ventilation (BiPAP) as preventative, supportive care for hospitalized, medically stable children with SCD on a general pediatric inpatient unit.

METHODS

Retrospective chart review of patients ≤22 years of age with SCD admitted to the general pediatric inpatient unit from February 1, 2017 to March 1, 2020 for whom BiPAP was recommended as supportive care. Hospitalizations were excluded if patients were admitted to the pediatric intensive care unit (PICU), required BiPAP for respiratory failure, or used BiPAP at home for obstructive sleep apnea.

RESULTS

Twenty-three patients had 53 hospitalizations in which BiPAP was recommended. Fifty-two (98%) hospitalizations included acute SCD pain. Indications for BiPAP included prior ACS (94%), chest or back pain (79%), and/or oxygen desaturation (66%). On 17 occasions, patients already had mild to moderate ACS but were stable when BiPAP was recommended. BiPAP was used successfully during 75% of hospitalizations for a median of two nights. There were no adverse effects associated with BiPAP. PICU transfer for respiratory support occurred during three hospitalizations. In 26 hospitalizations of children at risk for ACS who tolerated BiPAP, 23 (88%) did not develop ACS.

CONCLUSIONS

BiPAP is safe, feasible, and well tolerated as supportive care for hospitalized children with SCD. Next steps include an intervention trial to further assess the efficacy of BiPAP on ACS prevention.

Nocturnal hypoxemia measured by polysomnogram is associated with acute chest syndrome in pediatric sickle cell disease

STUDY OBJECTIVES

Nocturnal hypoxemia is associated with increased risk of sickle cell disease (SCD) complications. The association of nighttime hypoxemia and acute chest syndrome (ACS) in children with SCD has yet to be determined.

METHODS

This is a retrospective study of children with SCD who underwent polysomnography at a SCD center. Univariate logistic regression was used to assess the association between nocturnal hypoxemia and ACS admissions. Multivariate logistic regression was performed to verify the effects of different clinical covariates on ACS. Secondary analysis comparing patients with one vs multiple ACS admissions was performed.

RESULTS

One hundred ten individuals with SCD who completed their polysomnogram (mean age of 9.4 years) were identified. Fifty-nine (54%) had a history of at least one episode of ACS admission (mean age of 4.1 years), including 40 with multiple episodes. The percentage of total sleep time with O₂ saturation < 90% was greater in the ACS group (P < .05). Similarly, mean nocturnal O₂ saturation was lower in the ACS group (P < .0005). Mean nocturnal O₂ saturation of < 97.3% and the percentage of total sleep time with O₂ saturation < 90% higher than 2.7% were associated with ACS. There was no difference in nocturnal hypoxemia between patients with single and multiple ACS admissions.

CONCLUSIONS

Nocturnal hypoxemia later in life is associated with previous ACS admissions in children with SCD. This can increase the yield of interpreting polysomnograms in this vulnerable population. Prospective studies are needed to determine the temporal relations of nocturnal hypoxemia and ACS, which may identify a modifiable risk for ACS.

Sickle Cell Disease and the Respiratory System: A Tangential Perspective to the Hematopulmonological Dilemma

Sickle cell disease (SCD) is a genetically inherited hematological condition that predominantly affects the African-American subset of the population. It leads to the precipitation of multi-systematic manifestations throughout the course of the life of the patient leading to an increased rate of inpatient admissions and decreased quality of life. This article has reviewed some of the most common pulmonary complications of SCD with a brief overview of the clinical features and their management and has also highlighted the fatality of the complications placing a strong focus on screening, monitoring, and the treatment of the disease. The article has also discussed the management of SCD from a pulmonological perspective rather than hematological alone.

IL-6 levels are dramatically high in the sputum from children with sickle cell disease during acute chest syndrome

Sputum interleukin-6 (IL-6) level is high during acute chest syndrome (ACS) in pediatric sickle cell disease, supporting anti–IL-6 trials. Sputum IL-8, CCL2, and CCL3 levels are also high during ACS, possibly contributing to recruitment of inflammatory cells in the lungs.

Impact of COVID-19 on vasooclusive crisis in patients with sickle cell anaemia

Objectives

The study aimed to assess COVID-19 impact on the morbidity and mortality of vasooclusive crisis (VOC) in sickle cell anaemia (SCA) patients.

Methods

A prospective cohort study of 100 SCA patients; 50 with COVID-19 (COVID group) and 50 without (non-COVID group). All patients signed written informed consent.

Results

The COVID group had a significantly higher VOC episode median per year; 3 (IQR,1-6) vs 2 (IQR,2-12) (P < 0.05). The need for hospitalisation was similar in both groups. The non-COVID group had more history of culture-proven infection (P = 0.05). The COVID-group had more osteonecrosis (P < 0.05), splenic sequestration, splenomegaly and hepatic crisis (P = 0.05, 0.006, 0.02; respectively) and significantly higher (P < 0.05) symptoms of fever, cough, fatigue, abdominal pain and anosmia. Mean haemoglobin, lymphocyte subset, platelets, and reticulocytes were reduced in both groups, while lactate dehydrogenase and ferritin levels were significantly elevated. In the COVID group, the rise in white blood cell count, reticulocyte percentage, platelets and ferritin was subdued (P < 0.05). Two patients in the COVID group and 3 in the non-COVID group died; there was no statistically significant difference in mortality.

Conclusions

Although COVID-19 may have triggered the onset of VOC, it did not significantly influence VOC-related morbidity or mortality in this SCA cohort.

Management of Sickle Cell Disease Complications Beyond Acute Chest Syndrome

Sickle cell disease results in numerous complications that can lead to significant morbidity and mortality. Amongst them, acute chest syndrome is the leading cause of mortality. As a result, most providers are in tune with this complication and well versed with management. As sickle cell patients now live longer, they face a multitude of other complications that if left unattended, can lead to significant morbidity and mortality as well. It is critical to look beyond acute chest syndrome and adopt a more comprehensive approach to the management of the sickle cell patient.

Host genetic effects in pneumonia

Given the coronavirus disease 2019 (COVID-19) pandemic, investigations into host susceptibility to infectious diseases and downstream sequelae have never been more relevant. Pneumonia is a lung disease that can cause respiratory failure and hypoxia and is a common complication of infectious diseases, including COVID-19. Few genome-wide association studies (GWASs) of host susceptibility and severity of pneumonia have been conducted. We performed GWASs of pneumonia susceptibility and severity in the Vanderbilt University biobank (BioVU) with linked electronic health records (EHRs), including Illumina Expanded Multi-Ethnic Global Array (MEGAEX)-genotyped European ancestry (EA, n= 69,819) and African ancestry (AA, n = 15,603) individuals. Two regions of large effect were identified: the CFTR locus in EA (rs113827944; OR = 1.84, p value = 1.2 × 10-36) and HBB in AA (rs334 [p.Glu7Val]; OR = 1.63, p value = 3.5 × 10-13). Mutations in these genes cause cystic fibrosis (CF) and sickle cell disease (SCD), respectively. After removing individuals diagnosed with CF and SCD, we assessed heterozygosity effects at our lead variants. Further GWASs after removing individuals with CF uncovered an additional association in R3HCC1L (rs10786398; OR = 1.22, p value = 3.5 × 10-8), which was replicated in two independent datasets: UK Biobank (n = 459,741) and 7,985 non-overlapping BioVU subjects, who are genotyped on arrays other than MEGAEX. This variant was also validated in GWASs of COVID-19 hospitalization and lung function. Our results highlight the importance of the host genome in infectious disease susceptibility and severity and offer crucial insight into genetic effects that could potentially influence severity of COVID-19 sequelae.

Hemoglobinopathy and pediatrics in the time of COVID-19

INTRODUCTION

It is important to know if patients with hemoglobinopathy could be more susceptible to COVID-19.

OBJECTIVE

Analyze SARS-CoV-2 infection in pediatric patients with hemoglobinopathy.

METHODS

Using the online platforms LILACS, PUBMED and EMBASE, on 17- JUL-2020 a search was made for the terms COVID-19 and SARS-CoV-2 associated with "sickle cell", "thalassemia" and "hemoglobinopathy".

RESULTS

There were 623 pediatric and adult patients with sickle cell disease (SCD) or beta thalassemia (BT) and COVID-19. Total mortality rate was 6.42%. No pediatric patient with BT has been described. So, our analysis focused on children and adolescents with SCD: there were 121 pediatric patients, one adolescent died, prophylactic anticoagulation was prescribed to six patients, 11.76% needed intensive care unit, blood transfusion was prescribed in 29.70%. Vaso-occlusive crisis (VOC) and acute chest syndrome (ACS) were the main clinical manifestations in SCD.

DISCUSSION

Pediatric patients with SCD and COVID-19 have a low mortality rate when compared to adults, although is higher than the global pediatric population with COVID-19 (0-0.67%). The comorbidities associated with age and the long-term complications inherent to hemoglobinopathies may contribute to the increased mortality outside the pediatric age group. In SCD the clinical manifestations, both in children and adults, are VOC and ACS, and there was increase in blood requirement. Pediatric SCD patients with COVID-19 need more intensive care unit than the global pediatric population (3.30%).

CONCLUSION

Despite pediatric population with SCD needs more intensive care, the outcome after infection by COVID-19 is favorable.

COVID-19 Infection and Acute Pulmonary Embolism in an Adolescent Female With Sickle Cell Disease

A previously healthy 20-year-old female presented to the emergency room in April 2020 with complaints of shortness of breath, chest pain, and cough. She was diagnosed with coronavirus disease 2019 (COVID-19) infection and pulmonary embolism (PE). Workup for anemia led to the diagnosis of sickle cell disease (SCD). Patients diagnosed with COVID-19 are at an increased risk for the development of PE and venous thromboembolism (VTE). Anticoagulation prophylaxis and escalation to treatment dosing are recommended in patients admitted with moderate to severe symptoms of COVID-19. PE and VTE are relatively uncommon in the pediatric and adolescent population. Most commonly, patients are diagnosed with thrombophilia or have an underlying hypercoagulable state such as with SCD. Also, symptoms of COVID-19 infection, acute chest syndrome (ACS), and PE can have overlapping features. In this report, we present a case of a late adolescent female with SCD, who was diagnosed with COVID-19, and whose condition was complicated with PE.

Outcomes of a preoperative risk-based transfusion assignment protocol in sickle cell disease patients: a single-center retrospective study from Saudi Arabia

Many patients with sickle cell disease (SCD) need surgical management during their lifetime. The best approach for preoperative transfusion in SCD is still to be determined. In this single-center retrospective study, we included HBSS/HBS-Beta⁰-thalassemia patients younger than 16 years of age who underwent surgery between January 2008 and July 2019. Preoperative transfusion assignment (PTA) was based on SCD severity and surgical risk. Patients were assigned to no transfusion, simple transfusion, or exchange transfusion. A total of 284 patients were identified and 66 (23%) underwent 78 procedures. Mean age at the time of procedure was 8 (5-11) years, mean baseline hemoglobin was 8.5 (7.8-9.3) g/dl, and mean hemoglobin F was 18.4 ± 8.2%. SCD severity was low-risk in 57 (73%) and high-risk in 21 (27%) patients. Surgical risk was low-risk in 20 (25.6%) and medium-risk in 58 (74.4%) procedures. PTA was no transfusion in 17 (22%), simple transfusion in 40 (51%), and exchange transfusion in 21 (27%) procedures. Postoperative complications occurred in five (6.4%) of procedures only in the simple transfusion group (three acute chest syndrome, one hemolytic anemia, one pain crisis) undergoing medium-risk surgery. Preoperative risk-based transfusion assignment is feasible. Despite a high baseline hemoglobin level in the no transfusion group, none of the patients developed postoperative complications. It is possible that the high baseline hemoglobin F phenotype was protective and indicates the need to study the risk/benefit of interventions used in this phenotype.

The Meaning of Informed Consent: Genome Editing Clinical Trials for Sickle Cell Disease

BACKGROUND

A first therapeutic target of somatic genome editing (SGE) is sickle cell disease (SCD), the most commonly inherited blood disorders, affecting more than 100,000 individuals in the United States. Advancement of SGE is contingent on patient participation in first in human clinical trials. However, seriously ill patients may be vulnerable to overestimating the benefits of early phase studies while underestimating the risks. Therefore, ensuring potential clinical trial participants are fully informed prior to participating in a SGE clinical trial is critical. Methods: We conducted a mixed-methods study of adults with SCD as well as parents and physicians of individuals with SCD. Participants were asked to complete a genetic literacy survey, watch an educational video about genome editing, complete a two-part survey, and take part in focus group discussions. Focus groups addressed topics on clinical trials, ethics of gene editing, and what is not understood regarding gene editing. All focus groups were audio-recorded, transcribed, and analyzed using conventional content analysis techniques to identify major themes. Results: Our study examined the views of SCD stakeholders regarding what they want and need to know about genome editing to make an informed decision to participate in a SGE clinical trial. Prominent themes included stakeholders' desire to understand treatment side effects, mechanism of action of SGE, trial qualification criteria, and the impact of SGE on quality of life. In addition, some physicians expressed concerns about the extent to which their patients would understand concepts related to SGE; however, individuals with SCD demonstrated higher levels of genetic literacy than estimated by physicians. Conclusions: Designing ethically robust genome editing clinical trials for the SCD population will require, at a minimum, addressing the expressed information needs of the community through culturally sensitive engagement, so that they can make informed decisions to consider participation in clinical trials.

Changes in Blood Profile from Steady State in Patients with Sickle Cell Anemia Admitted for Vaso-occlusive Crisis and Acute Chest Syndrome

Close to half of all patients with sickle cell disease (SCD) will have at least one episode of acute chest syndrome (ACS) during their lifetime. Multiple cells and molecules involved with the inflammatory cascade play a role in the development of ACS. We found that patients with SCD who developed ACS as a complication of a vaso-occlusive crisis (VOC) had a significant increase in leukocytes and decrease in platelets from their steady state when compared with a separate admission for VOC without ACS development. No significant change from steady state hemoglobin or reticulocyte count was noted between the two admissions. These results indicate that trending laboratory markers may be useful to predict patients at risk for ACS development.

How I Treat Acute Chest Syndrome in Asthmatic Children with Sickle Cell Disease. A Practical Review

Asthma is associated with increased rate of acute chest syndrome (ACS), pain episodes and premature death. Differentiating between an acute asthma exacerbation and ACS is a challenge clinically as they can present with similar symptoms. Clinicians should be aware of symptoms of asthma or broncho spasm in any children with sickle cell disease, as adequate treatments are required. In this mini-review, we selected 16 clinical studies, published in English between 2004 and 2016, and reviewed all of the abstracts and references of the selected articles. We subsequently selected articles that were focused on asthma in children with sickle cell disease. Given the pathophysiological mechanisms of ACS and the association between asthma and sickle cell disease, the management approach of asthmatic children should be clarified. Bronchodilators should be used if there are clinical features suggestive of a history of asthma or evidence of acute broncho spasm. The indication for cortisone should be reassessed. This literature review failed to conclude on therapeutic modalities of ACS in asthmatic children with sickle cell disease. Only a well designed, multicenter adequately-powered randomized controlled study of each of them will allow assessing their real benefits and risks.

Polymorphisms in Inflammatory Genes Modulate Clinical Complications in Patients With Sickle Cell Disease

Sickle cell disease (SCD), the most common monogenic disease worldwide, is marked by a phenotypic variability that is, to date, only partially understood. Because inflammation plays a major role in SCD pathophysiology, we hypothesized that single nucleotide polymorphisms (SNP) in genes encoding functionally important inflammatory proteins might modulate the occurrence of SCD complications. We assessed the association between 20 SNPs in genes encoding Toll-like receptors (TLR), NK cell receptors (NKG), histocompatibility leukocyte antigens (HLA), major histocompatibility complex class I polypeptide-related sequence A (MICA) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), and the occurrence of six SCD clinical complications (stroke, acute chest syndrome (ACS), leg ulcers, cholelithiasis, osteonecrosis, or retinopathy). This study was performed in a cohort of 500 patients. We found that the TLR2 rs4696480 TA, TLR2 rs3804099 CC, and HLA-G, rs9380142 AA genotypes were more frequent in patients who had fewer complications. Also, in logistic regression, the HLA-G rs9380142 G allele increased the risk of cholelithiasis (AG vs. AA, OR 1.57, 95%CI 1.16-2.15; GG vs. AA, OR 2.47, 95%CI 1.34-4.64; P = 0.02). For SNPs located in the NKG2D loci, in logistic regression, the A allele in three SNPs was associated with a lower frequency of retinopathy, namely, rs2246809 (AA vs. GG: OR 0.22, 95%CI 0.09-0.50; AG vs. GG: OR 0.47, 95%CI 0.31-0.71; P = 0.004, for patients of same origin), rs2617160 (AT vs. TT: OR 0.67, 95%CI 0.48-0.92; AA vs. TT: OR 0.45, 95%CI 0.23-0.84; P = 0.04), and rs2617169 (AA vs. TT: OR 0.33, 95%CI 0.13-0.82; AT vs. TT: OR 0.58, 95%CI 0.36-0.91, P = 0.049, in patients of same SCD genotype). These results, by uncovering susceptibility to, or protection against SCD complications, might contribute to a better understanding of the inflammatory pathways involved in SCD manifestations and to pave the way for the discovery of biomarkers that predict disease severity, which would improve SCD management.

Spirometry use in Patients with Sickle Cell Disease with and without asthma and acute chest syndrome: A Multicenter Study

A de-identified data repository of electronic medical record (EMR) data, i2b2 (Informatics for Integrating Biology and the Bedside), including 4 geographically diverse academic medical centers, was queried to determine the use of diagnostic spirometry testing in African American children and young adults 5-34 years old with sickle cell disease (SCD) with or without a documented history of asthma and/or acute chest syndrome (ACS). A total of 2,749 patients were identified with SCD, of these 577 had asthma and 409 had ACS. Cross-referencing the CPT code for diagnostic spirometry showed that for patients identified as having SCD, a history or ACS, and a diagnosis of asthma, only 31% across all 4 centers had spirometry. Having an asthma diagnosis was associated with ACS. Among SCD patients with asthma, the proportion with ACS for the four centers was 47%, 75%, 38%, and 36% respectively. The bivariate association between asthma and ACS for each Center was significant for each (p<.001). To summarize, only one third of patients with co-morbid SCD, ACS, and asthma received the spirometry procedure as recommended in evidence-based guidelines, suggesting limited testing for changes in pulmonary function. Future studies to determine barriers and facilitators to implementation of pulmonary testing in SCD are warranted.

Baseline and Disease-Induced Transcriptional Profiles in Children with Sickle Cell Disease

Acute chest syndrome (ACS) is a significant cause of morbidity and mortality in sickle cell disease (SCD), but preventive, diagnostic, and therapeutic options are limited. Further, ACS and acute vasoccclusive pain crises (VOC) have overlapping features, which causes diagnostic dilemmas. We explored changes in gene expression profiles among patients with SCD hospitalized for VOC and ACS episodes to better understand ACS disease pathogenesis. Whole blood RNA-Seq was performed for 20 samples from children with SCD at baseline and during a hospitalization for either an ACS (n = 10) or a VOC episode (n = 10). Respiratory viruses were identified from nasopharyngeal swabs. Functional gene analyses were performed using modular repertoires, IPA, Gene Ontology, and NetworkAnalyst 3.0. The VOC group had a numerically higher percentage of female, older, and hemoglobin SS participants compared to the ACS group. Viruses were detected in 50% of ACS cases and 20% of VOC cases. We identified 3004 transcripts that were differentially expressed during ACS episodes, and 1802 transcripts during VOC episodes. Top canonical pathways during ACS episodes were related to interferon signaling, neuro-inflammation, pattern recognition receptors, and macrophages. Top canonical pathways in patients with VOC included IL-10 signaling, iNOS signaling, IL-6 signaling, and B cell signaling. Several genes related to antimicrobial function were down-regulated during ACS compared to VOC. Gene enrichment nodal interactions demonstrated significantly altered pathways during ACS and VOC. A complex network of changes in innate and adaptive immune gene expression were identified during both ACS and VOC episodes. These results provide unique insights into changes during acute events in children with SCD.

Sickle cell disease as a vascular disorder

INTRODUCTION

In sickle cell disease (SCD), hemoglobin S (HbS) red blood cells (RBCs) are characteristically deformed and inflexible. Often breaking down in the circulation, they exhibit increased adhesive properties with the endothelium and activated neutrophils and platelets, increasing the risk of occlusion of the microcirculation. SCD is categorized into two sub-phenotypes: hyperhemolytic, associated with priapism, leg ulcers, pulmonary hypertension, and stroke, and high hemoglobin/viscosity, which may promote vaso-occlusion-associated pain, acute chest syndrome, and osteonecrosis.

AREAS COVERED

The sub-phenotypes are not completely distinct. Hemolysis may trigger vaso-occlusion, contributing to vascular complications. Targeting P-selectin, a key mediator of cross-talk between hyperhemolysis and vaso-occlusion, may be beneficial for vascular and vaso-occlusion-associated complications. English-language articles from PubMed on the topic of SCD and vaso-occlusive crises (VOCs) were reviewed from 1 January 2000 to 1 January 2019 using the search terms 'sickle cell disease,' 'vaso-occlusive crises,' and 'selectin.'

EXPERT OPINION

Besides targeting P-selectin, other strategies to counter VOCs and RBC sickling are being pursued. These include platelet inhibition to counter aggregation, intercellular adhesion, and thrombosis during VOCs; gene therapy to correct the homozygous missense mutation in the β-globin gene, causing polymerization of HbS; L-glutamine, possibly reducing oxidative stress in sickled RBCs; and fetal hemoglobin inducers.

Veno-Venous Extracorporeal Membrane Oxygenation in Adult Patients with Sickle Cell Disease and Acute Chest Syndrome: a Single-Center Experience

Acute chest syndrome (ACS) in adult patients with sickle cell disease represents a leading cause of death. It is characterized by a new density on chest X-ray accompanied by fever and/or respiratory symptoms. Currently, 49 adult patients with sickle cell disease are registered at our department. By now, 12 patients (24.5%) suffered from ACS and two patients showed multiple/recurrent (>2) episodes. Death in one patient was related to acute respiratory failure secondary to ACS. In three patients with ACS, invasive mechanical ventilation and subsequent veno-venous extracorporeal membrane oxygenation (VV-ECMO) was mandatory. Veno-venous ECMO was applied within 24 hours upon arrival to the intensive care unit (ICU). All patients were treated aggressively for ACS including exchange transfusions [packed red blood cell (pRBC) units 5-16] maintaining a Hb S threshold of <30.0% in addition to broad-spectrum antibiotics, resulting in a successful outcome following decannulation from VV-ECMO (49 hours, 251 hours, 30 min., and 98 hours, respectively). Limited information is presently available on the use of VV-ECMO in adult patients with sickle cell disease in the context of acute respiratory failure secondary to ACS. The adequate timing of the decision to place ECMO in critically ill adults with sickle cell disease, incapable of being treated by conventional mechanical ventilation secondary to very severe vaso-occlusive crisis (VOC), might further reduce mortality rates while treating the underlying condition.

Predictors of impending acute chest syndrome in patients with sickle cell anaemia

Acute chest syndrome (ACS) is a major complication of sickle cell anaemia (SCA) and a leading cause for hospital admissions and death. We aimed to study the spectrum of clinical and laboratory features of ACS and to assess the predisposing factors and predictors of severity. A retrospective case-control cohort was studied by retrieving patient information from electronic medical records after ethical approval. One hundred adolescents and adults with SCA and hospital admissions for ACS were identified through the discharge summaries, along with 20 additional patients presenting with VOC, but without ACS (controls). Among the patients with ACS, fever (>38.5 °C), reduced oxygen saturation (<95) and asplenia significantly differed when compared to those of controls (p < 0.05, chi-squared test). The degree of severity was reflected in the use of non-invasive ventilation (NIV), simple and exchange transfusions, and the presence of bilateral pleural effusions and multi-lobar atelectasis/consolidation, which were significantly higher in the cases with ACS than in the controls. Lower haemoglobin (Hb) and high WBC counts were also significantly different between the two groups (p < 0.05, Student's t test). Using logistic regression, our study further demonstrated that asplenia, fever, and reduced O₂ saturation, along with low Hb and leukocytosis, were important predictors for the development of ACS.

Life-Threatening Infectious Complications in Sickle Cell Disease: A Concise Narrative Review

Sickle cell disease (SCD) results in chronic hemolytic anemia, recurrent vascular occlusion, insidious vital organ deterioration, early mortality, and diminished quality of life. Life-threatening acute physiologic crises may occur on a background of progressive diminishing vital organ function. Sickle hemoglobin polymerizes in the deoxygenated state, resulting in erythrocyte membrane deformation, vascular occlusion, and hemolysis. Vascular occlusion and increased blood viscosity results in functional asplenia and immune deficiency in early childhood, resulting in life-long increased susceptibility to serious bacterial infections. Infection remains a main cause of overall mortality in patients with SCD in low- and middle-income countries due to increased exposure to pathogens, increased co-morbidities such as malnutrition, lower vaccination rates, and diminished access to definitive care, including antibiotics and blood. Thus, the greatest gains in preventing infection-associated mortality can be achieved by addressing these factors for SCD patients in austere environments. In contrast, in high-income countries, perinatal diagnosis of SCD, antimicrobial prophylaxis, vaccination, aggressive use of antibiotics for febrile episodes, and the availability of contemporary critical care resources have resulted in a significant reduction in deaths from infection; however, chronic organ injury is problematic. All clinicians, regardless of their discipline, who assume the care of SCD patients must understand the importance of infectious disease as a contributor to death and disability. In this concise narrative review, we summarize the data that describes the importance of infectious diseases as a contributor to death and disability in SCD and discuss pathophysiology, prevalent organisms, prevention, management of acute episodes of critical illness, and ongoing care.

Pulmonary Edema in Hb S/β+ thalassemia Patient Leading to Acute Chest Syndrome. A Case Report and Review of Literature

Acute chest syndrome (ACS) is associated with prolonged hospitalization and high mortality in sickle cell population. The etiology of ACS is often multifactorial. It is well known that any chest pain that limits ventilation, blood flow or oxygenation establishes the risk of ACS. The independent contributory mechanism is fluid overload, resulting in pulmonary edema. In this report, we present a case of compound heterozygous Hb S/β+ thalassemia in a 32-year-old woman who presented with chest pain complicated by the development of pulmonary edema advancing to acute chest syndrome. We discuss the putative mechanisms might have led to pulmonary edema in this patient including hydration with underlying renal defect, along with a vicious cycle of vascular changes that resulted into pulmonary edema and consequently ACS.

Genetic Modifiers at the Crossroads of Personalised Medicine for Haemoglobinopathies

Haemoglobinopathies are common monogenic disorders with diverse clinical manifestations, partly attributed to the influence of modifier genes. Recent years have seen enormous growth in the amount of genetic data, instigating the need for ranking methods to identify candidate genes with strong modifying effects. Here, we present the first evidence-based gene ranking metric (IthaScore) for haemoglobinopathy-specific phenotypes by utilising curated data in the IthaGenes database. IthaScore successfully reflects current knowledge for well-established disease modifiers, while it can be dynamically updated with emerging evidence. Protein-protein interaction (PPI) network analysis and functional enrichment analysis were employed to identify new potential disease modifiers and to evaluate the biological profiles of selected phenotypes. The most relevant gene ontology (GO) and pathway gene annotations for (a) haemoglobin (Hb) F levels/Hb F response to hydroxyurea included urea cycle, arginine metabolism and vascular endothelial growth factor receptor (VEGFR) signalling, (b) response to iron chelators included xenobiotic metabolism and glucuronidation, and (c) stroke included cytokine signalling and inflammatory reactions. Our findings demonstrate the capacity of IthaGenes, together with dynamic gene ranking, to expand knowledge on the genetic and molecular basis of phenotypic variation in haemoglobinopathies and to identify additional candidate genes to potentially inform and improve diagnosis, prognosis and therapeutic management.

Prevalence of Hepatitis B, Hepatitis C, and HIV in Multiply Transfused Sickle Cell Disease Patients from Oman

Background

In Oman, the prevalence of hepatitis B (HBV) infection is 5.8%, with 2.8–7.1% HBV carriers. Hepatitis C (HCV) prevalence among Omanis is 0.41%. A total of 2917 human immunodeficiency virus (HIV) infections were notified among Omanis by 2017. This study was performed as there was no data on the prevalence of HIV, HBV and HCV in sickle cell disease (SCD) patients from Oman.

Study Design and Methods

In this retrospective, cross-sectional study, medical records of all SCD patients who attended our hospital between 2011 to 2017 were retrieved from the hospital information system. Following approval by the local medical research and ethics committee, data on HIV, HBV, and HCV exposure were recorded to estimate the prevalence.

Results

Among a total of 1000 SCD patients (491 males and 509 females), twenty-three (2.3%) patients showed positive serology for hepatitis B surface antigen (HbsAg), of whom sixteen (1.6%) were HBV DNA positive. 126 (12.6%) had anti-HCV antibodies (anti-HCV), of whom fifty-two (5.2%) were HCV RNA positive. None of the patients had positive serology for HIV. A normal liver was observed on abdominal ultrasound in 788 (78.8%) patients, whereas 208 (20.8%) had hepatomegaly, and 4 (0.4%) had liver cirrhosis. Thirty-six (3.6%) patients died, but in only two patients, the mortality was due to cirrhosis of liver.

Conclusions

This study provides the first comprehensive data on the prevalence of HBV and HCV infections among Omani SCD patients exposed to blood transfusions. Reassuringly, no case with HIV was observed.

Identification of Clinical and Laboratory Parameters Associated with the Development of Acute Chest Syndrome during Vaso-Occlusive Episodes in Children with Sickle Cell Disease: A Preliminary Step before Assessing Specific and Early Treatment Strategies

This prospective observational study sought to ascertain clinical and laboratory parameters associated with the development of acute chest syndrome (ACS) during vaso-occlusive episodes (VOE) in children with sickle cell disease (SCD). It was performed at the pediatric department of the university Intercommunal Créteil hospital. All children with SCD (all sickle genotypes) consecutively admitted from November 2013 to December 2016 for painful VOEs and no evidence of ACS were included. Clinical and laboratory parameters collected at admission and within 48 h after admission were compared for children in whom ACS developed or not. Variables that were statistically significant on univariate analysis or considered to be clinically relevant were included in a multivariable model to ascertain the risk factors associated with the development of ACS during a VOE. The variables retained in the multivariate model were used to construct a predictive score for ACS. For each included child and during the study period, only data from the first VOE and/or the first ACS were analyzed. Among 191 hospitalizations for painful VOEs, for 176 children with SCD, ACS developed in 35 during hospitalization. Mean hospital stay was longer for children with ACS versus VOEs alone (7.6 (±2.3) vs. 3.3 (±1.8) days, p < 0.0001), and all children with ACS versus 28/156 (17.9%) with VOEs alone received red blood cell transfusion (p < 0.0001). The multivariate model retained pain score (≥9/10), pain localization (abdominal or spinal pain or involving more than two limbs), and high reticulocyte (≥260 × 10⁹/L) and neutrophil (>10 × 10⁹/L) counts, at admission, as independently associated with ACS development. The area under the receiver operating characteristic curve for the ACS predictive score was 0.82 (95% CI: 0.74–0.89), and the negative predictive value was 97.7%. The evolution profiles during the first 48 h differed between children with ACS and VOEs alone, with a more rapid decline of pain score and leucocytosis in children with VOEs. Clinical and laboratory measurements at admission may be simple parameters to identify children with increased risk of ACS development during VOEs and to facilitate early diagnosis of this respiratory complication. Also, the persistent elevation of leukocyte count on day 2 may be considered a sign of evolving ACS.

Low-risk factors for severe bacterial infection and acute chest syndrome in children with sickle cell disease

INTRODUCTION

The rate of bacterial infections in children with sickle cell disease (SCD) has decreased in recent years, mainly due to penicillin prophylaxis and vaccination.

OBJECTIVES

To determine the rate of severe bacterial infection (SBI) in a cohort of children with SCD and to describe low-risk factors for confirmed SBI (CSBI) and acute chest syndrome (ACS).

METHODS

This 11-year retrospective cohort study included children with febrile SCD admitted to a reference hospital in Spain. A case-control study was performed comparing patients diagnosed with SBI to those without SBI, and subanalyses for groups with CSBI and ACS were carried out.

RESULTS

A total of 316 febrile episodes were analyzed; 69 (21.8%) had confirmed or possible SBI. Thirteen of those had CSBI (4.1%), eight urinary tract infection, and five bacteremia/sepsis. Among the cases of possible SBI, the majority had ACS (54/56; 96.4%). Age >3 years, absence of central venous catheter, hemodynamic stability, and procalcitonin <0.6 ng/ml were low-risk factors for CSBI, whereas normal oxygen saturation and C-reactive protein <3 mg/dl were low-risk factors for ACS, with negative predictive values (NPV) of 98.3%, 97.4%, 96%, 97.2%, 87.5%, and 85.8%, respectively.

CONCLUSION

In this cohort of children with SCD who were well vaccinated and received adequate prophylaxis, we found a low rate of bacteremia and CSBI. We described several low-risk factors for CSBI and ACS, all of them with a high NPV. These findings may help to develop a risk score to safely select the patients that could be managed with a more conservative approach.

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.