Access to essential therapy for sickle cell disease in Africa: Experience from a national program in Ghana

Novartis, a global medicines company, and the Sickle Cell Foundation of Ghana (SCFG), an advocacy organization, have endeavored to support the implementation of global best practices in the care of people living with sickle cell disease (SCD) in Africa, and to address unmet needs relating to this condition on the continent. Beginning in 2019, a multifaceted SCD program was implemented in Ghana through a public-private partnership involving the government of Ghana, the SCFG, Novartis, and other partners. A key component of the program involved expanding the reach of hydroxyurea (HU), the only approved disease-modifying generic treatment for SCD, in ways that would promote sustainable access. The program helped to raise the profile of SCD in Ghana and, in 2022, the government adopted HU into its National Health Insurance Scheme. Features of the effort in Ghana are now being expanded to other countries in Africa through cocreated programs with in-country partners. This article reviews the program's history, progress, challenges, and lessons learned.

Development of multi-level standards of care recommendations for sickle cell disease: Experience from SickleInAfrica

Introduction: Sickle Cell Disease (SCD) causes significant morbidity and mortality particularly in sub-Saharan Africa (SSA) where it contributes to early childhood deaths. There is need to standardize treatment guidelines to help improve overall SCD patient health outcomes. We set out to review existing guidelines on SCD and to set minimum standards for management of SCD for the different referral levels of healthcare. Methods: A standards of care working group (SoC-WG) was established to develop the SoC recommendations. About 15 available SCD management guidelines and protocols were reviewed and themes extracted from them. The first draft was on chosen themes with 64 major headings and subtopics. Using a summarised WHO levels of referral document, we were able to get six different referral levels of healthcare. The highest referral level was the tertiary facilities whilst the lowest level was the home setting. Recommendations for SCD management for the regional, district, sub-districts, health posts and CHPs compounds were also drafted. Results: The results from this review yielded a guidelines document which had recommendations for management of SCD on 64 topics and subtopic for all the six (6) different referral levels. Discussions: Every child with SCD need to receive comprehensive care that is coordinated at each level. This recommendation is unique in terms of the availability of recommendations for different levels of care as compared to the traditional guidelines which is more focused at the tertiary levels. Patients can access care at any of the other lower referral hospitals and be managed with recommendations that are in keeping with institutional resources at that level. When such patients need care that requires expertise that is not available at that level, the recommendations will be to refer to the appropriate referral level where those expertise are available. This encourages patients to have good clinical care nearer their homes but also having access to specialist screening modalities and expertise at the tertiary hospitals if need be. With this, patient are not limited to a specific referral level when interventions cannot be instituted for them. Conclusion: This SoC recommendations document is a useful material that can be used for consistent standards of treatment in SSA.

Enablers and barriers to newborn screening for sickle cell disease in Africa: results from a qualitative study involving programmes in six countries

OBJECTIVES

Given the fundamental role of newborn bloodspot screening (NBS) to enable prompt diagnosis and optimal clinical management of individuals with sickle cell disease (SCD), we sought to systematically assess enablers and barriers to implementation of NBS programmes for SCD in Africa using established qualitative research methods.

SETTING

Childbirth centres and NBS laboratories from six countries in East, West and Southern Africa.

PARTICIPANTS

Eight programme leaders involved with establishing and operating NBS programmes for SCD in Angola, Democratic Republic of Congo, Ghana, Liberia, Nigeria and Tanzania.

PRIMARY AND SECONDARY OUTCOME MEASURES

Data obtained through a structured, phased interview approach were analysed using a combination of inductive and deductive codes and used to determine primary themes related to the implementation and sustainability of SCD NBS programmes.

RESULTS

Four primary themes emerged from the analysis relating to governance (eg, pragmatic considerations when deploying overcommitted clinical staff to perform NBS), technical (eg, design and execution of operational processes), cultural (eg, variability of knowledge and perceptions of community-based staff) and financial (eg, issues that can arise when external funding may effectively preclude government inputs) aspects. Key learnings included perceived factors that contribute to long-term NBS programme sustainability.

CONCLUSIONS

The establishment of enduring NBS programmes is a proven approach to improving the health of populations with SCD. Organising such programmes in Africa is feasible, but initial implementation does not assure sustainability. Our analysis suggests that future programmes should prioritise government partner participation and funding from the earliest stages of programme development.

Establishing a Sickle Cell Disease Registry in Africa: Experience From the Sickle Pan-African Research Consortium, Kumasi-Ghana

Sickle cell disease (SCD) is the most common clinically significant hemoglobinopathy, characterized by painful episodes, anemia, high risk of infection, and other acute and chronic complications. In Africa, where the disease is most prevalent, large longitudinal data on patients and their outcomes are lacking. This article describes the experiences of the Kumasi Center for SCD at the Komfo Anokye Teaching Hospital (KCSCD-KATH), a Sickle Pan-African Research Consortium (SPARCO) site and a SickleInAfrica Consortium member, in establishing a SCD registry for the evaluation of the outcomes of patients. It also provides a report of a preliminary analysis of the data. The process of developing the registry database involved comprehensive review of the center's SCD patient medical records, incorporating data elements developed by the SickleInAfrica Consortium and obtaining ethical clearance from the local Institutional Review Board. From December 2017 to March 2020, 3,148 SCD patients were enrolled into the SCD registry. Enrollment was during the SCD outpatient clinic visits or through home visits. A significant proportion of the patients was from the newborn screening cohort (50.3%) and was males (52.9%). SCD-SS, SCD-SC, and Sβ ⁺thalassemia were seen in 67.2, 32.5, and 0.3% patients, respectively. The majority of the patients were in a steady state at enrollment; however, some were enrolled after discharge for an acute illness admission. The top two clinical diagnoses for SCD-SS patients were sickle cell painful events and acute anemia secondary to hyperhemolysis with incidence rates of 141.86 per 10,000 person months of observation (PMO) and 32.74 per 10,000 PMO, respectively. In SCD-SC patients, the top two diagnoses were sickle cell painful events and avascular necrosis with incidence rates of 203.09 per 10,000 PMO and 21.19 per 10,000 PMO, respectively. The SPARCO Kumasi site has developed skills and infrastructure to design, manage, and analyze data in the SCD registry. The newborn screening program and alternative recruitment methods such as radio announcement and home visits for defaulting patients were the key steps taken in enrolling patients into the registry. The registry will provide longitudinal data that will help improve knowledge of SCD in Ghana and Africa through research.

Implementing newborn screening for sickle cell disease in Korle Bu Teaching Hospital, Accra: Results and lessons learned

BACKGROUND

Early diagnosis of sickle cell disease (SCD) through newborn screening (NBS) is a cost-effective intervention, which reduces morbidity and mortality. In sub-Saharan Africa (SSA) where disease burden is greatest, there are no universal NBS programs and few institutions have the capacity to conduct NBS. We determined the feasibility and challenges of implementing NBS for SCD in Ghana's largest public hospital.

PROCEDURE

The SCD NBS program at Korle Bu Teaching Hospital (KBTH) is a multiyear partnership between the hospital and the SickKids Center for Global Child Health, Toronto, being implemented in phases. The 13-month demonstration phase (June 2017-July 2018) and phase one (November 2018-December 2019) focused on staff training and the feasibility of universal screening of babies born in KBTH.

RESULTS

During the demonstration phase, 115 public health nurses and midwives acquired competency in heel stick for dried blood spot sampling. Out of 9990 newborns, 4427 babies (44.3%) were screened, of which 79 (1.8%) were identified with presumptive SCD (P-SCD). Major challenges identified included inadequate nursing staff to perform screening, shortage of screening supplies, and delays in receiving screening results. Strategies to overcome some of the challenges were incorporated into phase one, resulting in increased screening coverage to 83.7%.

CONCLUSIONS

Implementing NBS for SCD in KBTH presented challenges with implications on achieving and sustaining universal NBS in KBTH and other settings in SSA. Specific steps addressing these challenges comprehensively will help build on the modest initial gains, moving closer toward a sustainable national NBS program.

Utilization of Pneumococcal Vaccine and Penicillin Prophylaxis in Sickle Cell Disease in Three African Countries: Assessment among Healthcare Providers in SickleInAfrica

Sickle cell disease is a genetic disease with a predisposition to infections caused by encapsulated organisms, especially Streptococcus pneumoniae. Pneumococcal vaccines and prophylactic penicillin have reduced the rate of this infection and mortality in sickle cell disease. However, implementation of these interventions is limited in Africa. The objectives of the study were to assess health care providers' behaviors with the implementation of pneumococcal vaccination and penicillin prophylaxis and to identify barriers to their use. A 25-item online questionnaire was administered through SickleinAfrica: a network of researchers, and healthcare providers, in Ghana, Nigeria, and Tanzania, working to improve health outcomes of sickle cell disease in Africa. Data was collected and managed using the Research Electronic Data Capture (REDCap), tools and data analysis was done using STATA version 13 and R statistical software. Eighty-two medical practitioners responded to the questionnaire. Only 54.0 and 48.7% of respondents indicated the availability of published guidelines on sickle cell disease management and pneumococcal vaccine use, respectively, at their facilities. The majority (54.0%) perceived that the vaccines are effective but over 20.0% were uncertain of their usefulness. All respondents from Ghana and Tanzania affirmed the availability of guidelines for penicillin prophylaxis in contrast to 44.1% in Nigeria. Eighty-five percent of respondents affirmed the need for penicillin prophylaxis but 15.0% had a contrary opinion for reasons including the rarity of isolation of Streptococcus pneumoniae in African studies, and therefore, the uncertainty of its benefit. Lack of published guidelines on the management of sickle cell disease and doubts about the necessity of prophylactic measures are potential barriers to the implementation of effective interventions.

Empowering newborn screening programs in African countries through establishment of an international collaborative effort

In an effort to explore new knowledge and to develop meaningful collaborations for improving child health, the First Pan African Workshop on Newborn Screening was convened in June 2019 in Rabat, Morocco. Participants included an informal network of newborn screening stakeholders from across Africa and global experts in newborn screening and sickle cell disease. Over 150 attendees, representing 20 countries, were present including 11 African countries. The agenda focused on newborn screening rationale, techniques, system development, implementation barriers, ongoing research, and collaborations both globally and across Africa. We provide an overview of the workshop and a description of the newborn screening activities in the 11 African countries represented at the workshop, with a focus on sickle cell disease.

Exploring the Role of Shared Decision Making in the Consent Process for Pediatric Genomics Research in Cameroon, Tanzania, and Ghana

Background: It is customarily perceived that in Africa, decisions around research participation may be based not only on individual reflection but also on discussions with others. Some authors have argued that such decision making is reflective of a more traditional communitarian African worldview; one critique of such a perspective is that it is lacking an empirical grounding. In this study, we explore decision making around enrollment in sickle cell genomics research in three countries in Africa, namely, Ghana, Cameroon, and Tanzania. Particularly, we focus on exploring the role of shared decision making with regard to participating in genomic studies. Results: We involved 64 participants in 15 individual interviews or in 49 focus-group discussions with research participants in rural and urban Tanzania (n = 20), Ghana (n = 30), and Cameroon (n = 14). We used a vignette to explore decision making around enrollment of children in sickle cell genomics research. Data were imported in NVivo11 and analyzed using thematic content analysis. Our findings indicate that the majority of the participants from both rural and urban settings prefer to make their own individual decisions and not consult with extended family or community leaders. Shared decision making was only considered necessary for individuals who were perceived to be in some way vulnerable. Conclusion: We found very limited support for shared decision making as the primary process for decision making about research participation. While consultation was considered important to support individual decision making, particularly when parents were perceived as vulnerable, there was no suggestion in our data that shared decision making would be a more important or valuable means of seeking consent for research participation in the African research context.

Relation Between Religious Perspectives and Views on Sickle Cell Disease Research and Associated Public Health Interventions in Ghana

Sickle cell disease (SCD) is highly prevalent in Africa with a significant public health burden for under-resourced countries. We employed qualitative research methods to understand the ethical, legal, and social implications of conducting genomic research in SCD under the Human Heredity and Health in Africa (H3Africa) initiative. The present study focused on religious and cultural aspects of SCD with the view to identifying beliefs and attitudes relevant to public health interventions in Ghana. Thematic analyses from individual and group interviews revealed six key areas of importance, namely, reliance on a supreme being; religion as a disruptive influence on health behaviors; role of religious leaders in information sharing and decision-making; social, religious, and customary norms; health and religious/supernatural beliefs; and need for social education and support through church and community. Findings suggest that public health programs in Ghana should not only aim at increasing knowledge and awareness about SCD and its management but also create an understanding of the relevance of genomics and alternative technological advancement to diagnosis and ethical decision-making around available options for health seeking. Future research should engage communities to help address the ethical and social implications of a persuasive religious influence on SCD-related health decisions.

Organ damage in sickle cell disease study (ORDISS): protocol for a longitudinal cohort study based in Ghana

INTRODUCTION

Sickle cell disease is highly prevalent in Africa with a significant public health burden. Nonetheless, morbidity and mortality in sickle cell disease that result from the progression of organ damage is not well understood. The Organ Damage in Sickle Cell Disease Study (ORDISS) is designed as a longitudinal cohort study to provide critical insight into cellular and molecular pathogenesis of chronic organ damage for the development of future innovative treatment.

METHODS AND ANALYSIS

ORDISS aims to recruit children aged 0-15 years who attend the Kumasi Centre for Sickle Cell Disease based at the Komfo Anokye Teaching Hospital in Kumasi, Ghana. Consent is obtained to collect blood and urine samples from the children during specified clinic visits and hospitalisations for acute events, to identify candidate and genetic markers of specific organ dysfunction and end-organ damage, over a 3 year period. In addition, data concerning clinical history and complications associated with sickle cell disease are collected. Samples are stored in biorepositories and analysed at the Kumasi Centre for Collaborative Research in Tropical Medicine, Ghana and the Centre for Translational and International Haematology, University of Pittsburgh, USA. Appropriate statistical analyses will be performed on the data acquired.

ETHICS AND DISSEMINATION

Research ethics approval was obtained at all participating sites. Results of the study will be submitted for publication in peer-reviewed journals, and the key findings presented at national and international conferences.

Stakeholder Perspectives on Public Health Genomics Applications for Sickle Cell Disease: A Methodology for a Human Heredity and Health in Africa (H3Africa) Qualitative Research Study

Advances in omics technologies alone are not a guarantee that science will translate to robust responsible innovation that is firmly grounded in societal values. This study aimed to identify best practices for Ethical, Legal, and Social Implications (ELSI) research in Africa that allows for optimal integration of community perspectives into the design and implementation of genomics research. In a large sample of 346 stakeholders in Cameroon, Ghana, and Tanzania (59% women), we used a qualitative study design with a phenomenological approach and conducted 32 group and 74 individual interviews (25% rural). We imported interview recordings into NVivo software for analysis. We created a “concept map” to organize the coded information, with Perspectives on Genomics and Sickle Cell Disease (SCD) Public Health Interventions as the central themes. We found that (1) analyses of major subthemes across and within countries revealed differential knowledge and experiences of SCD, and perspectives on various aspects of research and genomics; (2) we were able to gather empirical data efficiently from urban and rural stakeholders, to study the issues related to sample sharing, consent processes, and return of clinical and genomic study results; (3) the concept of nondirectiveness in modern genetic medicine practice can be challenged by the views of stakeholders in the context of a high-burden disease such as SCD; and (4) linking community views to current and proposed public health interventions could be understood within the context of each specific country. Our work informs future qualitative social science and technology policy research designs on genomics applications in Africa.

Perspectives from NHLBI Global Health Think Tank Meeting for Late Stage (T4) Translation Research

Almost three-quarters (74%) of all the noncommunicable disease burden is found within low- and middle-income countries. In September 2014, the National Heart, Lung, and Blood Institute held a Global Health Think Tank meeting to obtain expert advice and recommendations for addressing compelling scientific questions for late stage (T4) research-research that studies implementation strategies for proven effective interventions-to inform and guide the National Heart, Lung, and Blood Institute's global health research and training efforts. Major themes emerged in two broad categories: 1) developing research capacity; and 2) efficiently defining compelling scientific questions within the local context. Compelling scientific questions included how to deliver inexpensive, scalable, and sustainable interventions using alternative health delivery models that leverage existing human capital, technologies and therapeutics, and entrepreneurial strategies. These broad themes provide perspectives that inform an overarching strategy needed to reduce the heart, lung, blood, and sleep disorders disease burden and global health disparities.

Community Health Workers as Support for Sickle Cell Care

Community health workers are increasingly recognized as useful for improving health care and health outcomes for a variety of chronic conditions. Community health workers can provide social support, navigation of health systems and resources, and lay counseling. Social and cultural alignment of community health workers with the population they serve is an important aspect of community health worker intervention. Although community health worker interventions have been shown to improve patient-centered outcomes in underserved communities, these interventions have not been evaluated with sickle cell disease. Evidence from other disease areas suggests that community health worker intervention also would be effective for these patients. Sickle cell disease is complex, with a range of barriers to multifaceted care needs at the individual, family/friend, clinical organization, and community levels. Care delivery is complicated by disparities in health care: access, delivery, services, and cultural mismatches between providers and families. Current practices inadequately address or provide incomplete control of symptoms, especially pain, resulting in decreased quality of life and high medical expense. The authors propose that care and care outcomes for people with sickle cell disease could be improved through community health worker case management, social support, and health system navigation. This paper outlines implementation strategies in current use to test community health workers for sickle cell disease management in a variety of settings. National medical and advocacy efforts to develop the community health workforce for sickle cell disease management may enhance the progress and development of "best practices" for this area of community-based care.

Community engagement to inform the development of a sickle cell counselor training and certification program in Ghana

Sickle cell disease (SCD) and sickle cell trait (SCT) are highly prevalent in Africa. Despite public health implications, there is limited understanding of community issues for implementing newborn screening and appropriate family counseling. We conducted a 3-day workshop in Kumasi, Ghana, with community leaders as lay program development advisors to assist the development and implementation of a Sickle Cell Counselor Training and Certification Program. We employed qualitative methods to understand cultural, religious, and psychosocial dimensions of SCD and SCT, including the advisors' attitudes and beliefs in relation to developing a culturally sensitive approach to family education and counseling that is maximally suited to diverse communities in Ghana. We collated advisors' discussions and observations in order to understand community issues and potential challenges and guide strategies for advocacy in SCD family education and counseling. Results from the workshop revealed that community leaders representing diverse communities in Ghana were engaged constructively in discussions about developing a culturally sensitive counselor training program. Key findings included the importance of improved knowledge about SCD among the public and youth in particular, the value of stakeholders such as elders and religious and traditional leaders, and government expectations of reduced SCD births. We submitted a report to the Ministry of Health in Ghana with recommendations for the next steps in developing a national sickle cell counselor training program. We named the program "Genetic Education and Counseling for Sickle Cell Conditions in Ghana" (GENECIS-Ghana). The first GENECIS-Ghana Training and Certification Program Workshop was conducted from June 8 to 12, 2015.

Newborn Screening for Sickle Cell Disease in Liberia: A Pilot Study

BACKGROUND

In malaria-endemic countries in West Africa, sickle cell disease (SCD) contributes to childhood mortality. Historically, Liberia had regions wherein hemoglobin S and beta-thalassemia trait were mutually exclusive. Data on hemoglobinopathies in the Monrovia, the capital, are outdated and do not reflect urban migration. Updating the epidemiology of SCD is necessary to plan a public health and clinical agenda. Neither newborn screening (NBS) nor screening tools were available in country. This pilot study aimed to determine the feasibility of NBS using a South-South partnership and define the incidence of sickle cell trait (SCT) and SCD in Monrovia.

PROCEDURE

This descriptive epidemiologic feasibility study collected dried blood spots from 2,785 consecutive newborns delivered at a hospital in Monrovia. Samples were analyzed by isoelectric focusing at a regional reference laboratory. Infants with SCD were referred for preventive care.

RESULTS

SCT occurred in 10.31% of infants screened. SCD occurred in 33 infants screened [1.19% (95% confidence interval [CI]: 0.79-1.59%)] (FS: 28/33, FSB: 2/33, FSA: 2/33, FSX: 1/33). There were no infants with FSC phenotype observed. Nonsickling hemoglobin phenotypes "FC" and "F" were each present in three infants screened. Seventy-six percent of infants with SCD were brought to care, demonstrating the feasibility of our approach.

CONCLUSIONS

The incidence of SCD and other hemoglobinopathies remains high in Liberia. Additional studies are needed to clarify sickle genotypes and identify the contribution of silent beta-thalassemia alleles. By developing regional partnerships, countries similar to Liberia can acquire current data to inform NBS as an important public health initiative toward improving child health.

Proceedings of a Sickle Cell Disease Ontology workshop - Towards the first comprehensive ontology for Sickle Cell Disease

Sickle cell disease (SCD) is a debilitating single gene disorder caused by a single point mutation that results in physical deformation (i.e. sickling) of erythrocytes at reduced oxygen tensions. Up to 75% of SCD in newborns world-wide occurs in sub-Saharan Africa, where neonatal and childhood mortality from sickle cell related complications is high. While SCD research across the globe is tackling the disease on multiple fronts, advances have yet to significantly impact on the health and quality of life of SCD patients, due to lack of coordination of these disparate efforts. Ensuring data across studies is directly comparable through standardization is a necessary step towards realizing this goal. Such a standardization requires the development and implementation of a disease-specific ontology for SCD that is applicable globally. Ontology development is best achieved by bringing together experts in the domain to contribute their knowledge.

The SCD community and H3ABioNet members joined forces at a recent SCD Ontology workshop to develop an ontology covering aspects of SCD under the classes: phenotype, diagnostics, therapeutics, quality of life, disease modifiers and disease stage. The aim of the workshop was for participants to contribute their expertise to development of the structure and contents of the SCD ontology. Here we describe the proceedings of the Sickle Cell Disease Ontology Workshop held in Cape Town South Africa in February 2016 and its outcomes. The objective of the workshop was to bring together experts in SCD from around the world to contribute their expertise to the development of various aspects of the SCD ontology.

Sickle cell disease and H3Africa: enhancing genomic research on cardiovascular diseases in African patients

Background

Sickle cell disease (SCD) has a high prevalence in sub-Saharan Africa. There are several cardiovascular phenotypes in SCD that contribute to its morbidity and mortality.

Discussion

SCD is characterised by marked clinical variability, with genetic factors playing key modulating roles. Studies in Tanzania and Cameroon have reported that singlenucleotide polymorphisms in BCL11A and HBS1L-MYB loci and co-inheritance of alpha-thalassaemia impact on foetal haemoglobin levels and clinical severity. The prevalence of overt stroke among SCD patients in Cameroon (6.7%) and Nigeria (8.7%) suggests a higher burden than in high-income countries. There is also some evidence of high burden of kidney disease and pulmonary hypertension in SCD; however, the burden and genetics of these cardiovascular conditions have seldom been investigated in Africa.

Conclusions

Several H3Africa projects are focused on cardiovascular diseases and present major opportunities to build genome-based research on existing SCD platforms in Africa to transform the health outcomes of patients.

Filterability of freshly-collected sickle erythrocytes under venous oxygen pressure without exposure to air

We previously found that blood samples collected from steady-state patients with sickle cell disease (SCD) without exposure to air contain a new type of reversibly sickled cells (RSCs) with blunt edges at a level of as high as 78%. Since partial oxygenation of once-deoxygenated sickled cells with pointy edges to near venous oxygen pressure generates similar sickled cells with blunt edges in vitro, we named them as partially oxygenated sickled cells (POSCs). On the other hand, partial deoxygenation of once-oxygenated SS cells to venous oxygen pressure generates partially deoxygenated sickled cells (PDSCs) with pointy edges. In this study, we obtained blood samples from 6 steady-state patients with SCD under venous oxygen pressure without exposure to air, subjected them to various oxygenation/deoxygenation/reoxygenation cycles, and studied their filterability through a membrane filter with pore diameter of 3μm, the theoretical minimum diameter of a capillary. Our results indicated that discocytes, POSCs with blunt edges, and irreversibly sickled cells could deform and pass through the filter, while PDSCs with pointy edges were rigid and could not. The filterability of SS cells seems to be related to the length and amount of deoxy-hemoglobin S fibers in the cells.

Using formative research to develop a counselor training program for newborn screening in Ghana

Sickle cell disease (SCD), sickle cell trait (SCT) and related conditions are highly prevalent in sub-Saharan Africa. Despite the public health implications, there is limited understanding of the unique needs regarding establishing and implementing extensive screening for newborns and appropriate family counseling. We sought to gain understanding of community attitudes and beliefs about SCD/SCT from counselors and potential counselors in Ghana; obtain their input about goals for counseling following newborn screening; and obtain guidance about developing effective counselor education. Five focus groups with 32 health care providers and health educators from 9 of 10 regions in Ghana were conducted by trained facilitators according to a structured protocol. Qualitative data were coded and categorized to reflect common themes. Saturation was achieved in themes related to genetics/inheritance; common complications of SCD; potential for stigmatization; marital strain; and emotional stress. Misconceptions about SCT as a form of SCD were prevalent as were cultural and spiritual beliefs about the causes of SCD/SCT. Potential positive aspects included affected children's academic achievement as compensation for physical limitations, and family cohesion. This data informed recommendations for content and structure of a counselor training program that was provided to the Ministry of Health in Ghana.

Sickle cell anemia: intracranial stenosis and silent cerebral infarcts in children with low risk of stroke

PURPOSE

Children with sickle cell anemia (SCA), who have mean blood flow velocities <170 cm/s in the terminal internal carotid (tICA) or middle cerebral (MCA) arteries on transcranial Doppler ultrasonography (TCD), are considered to be at low risk of stroke. The prevalence of intracranial stenosis, which raises the risk of stroke, is not known in these children. Here, we estimated the prevalence of stenosis and explored its association with silent cerebral infarcts determined based on Magnetic Resonance (MR) scans.

PATIENTS/METHODS

We studied prospectively a cohort of 67 children with SCA without prior clinically overt stroke or TIA (median age 8.8 years; range limits 2.3-13.1 years; 33 females) and with TCD mean velocity <170 cm/s. They underwent MR imaging of the brain and MR angiography of intracranial arteries.

RESULTS

In 7 children (10.5%, 95% CI: 4.9-20.3%) we found 10 stenoses, including 4 with isolated left tICA stenosis and 3 with multiple stenoses. We found silent infarcts in 26 children (37.7%, 95% CI: 27.2-49.5%). The median number of infarcts in an affected child was 2 (range limits: 1-9), median volume of infarcts was 171 mm(3) (range limits: 7-1060 mm(3)), and median infarct volume in relation to total brain volume was 0.020% (range limits: 0.001-0.101%). The number and volume of infarcts were significantly higher in children with arterial stenosis (both p=0.023).

CONCLUSIONS

The prevalence of intracranial arterial stenosis in children with SCA classified as at low risk of stroke by TCD mean velocity <170 cm/s is high. Children with stenosis are at higher risk of brain parenchymal injury as they have more silent cerebral infarcts.

Respiratory muscle force and lung volume changes in a population of children with sickle cell disease

Sickle cell disease (SCD) is a disorder known to impact the respiratory system. We sought to identify respiratory muscle force and lung volume relationships in a paediatric SCD population. Thirty-four SCD-SS subjects underwent pulmonary function testing. Height, weight, age, and gender-adjusted percent predicted maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values were compared to spirometry and lung volumes. Statistical analyses were performed using Pearson's correlation coefficient and paired two-tailed t-test. The mean ± standard deviation (SD) MIP and MEP was 69·6 ± 31·6 cm H2 O and 66·9 ± 22·9 cm H2 O, respectively, and mean ± SD percent predicted MIP (101·3 ± 45·9) exceeded MEP (72·1 ± 26·0) (P = 0·002). MIP correlated with forced vital capacity (FVC; r = 0·51, P = 0·001) and TLC (r = 0·54, P < 0·0001). MEP also correlated with FVC (r = 0·43, P = 0·011) and total lung capacity (TLC; r = 0·42, P = 0·013). Pearson's correlation coefficient testing yielded relationships between MIP and MEP (r = 0·64, P < 0·0001). SCD-SS patients showed correlations between respiratory muscle force and lung volume, and reduced percent predicted expiratory muscle force compared to inspiratory muscle force. Respiratory muscle strength may affect lung volumes in these patients, and expiratory muscles may be more susceptible than the diaphragm to SCD-induced vaso-occlusive damage.

Sickle cell disease: new opportunities and challenges in Africa

Sickle cell disease (SCD) is one of the most common genetic causes of illness and death in the world. This is a review of SCD in Africa, which bears the highest burden of disease. The first section provides an introduction to the molecular basis of SCD and the pathophysiological mechanism of selected clinical events. The second section discusses the epidemiology of the disease (prevalence, morbidity, and mortality), at global level and within Africa. The third section discusses the laboratory diagnosis and management of SCD, emphasizing strategies that been have proven to be effective in areas with limited resources. Throughout the review, specific activities that require evidence to guide healthcare in Africa, as well as strategic areas for further research, will be highlighted.

Upper airway lymphoid tissue size in children with sickle cell disease

BACKGROUND

The prevalence of obstructive sleep apnea syndrome (OSAS) is higher in children with sickle cell disease (SCD) as compared with the general pediatric population. It has been speculated that overgrowth of the adenoid and tonsils is an important contributor.

METHODS

The current study used MRI to evaluate such an association. We studied 36 subjects with SCD (aged 6.9 ± 4.3 years) and 36 control subjects (aged 6.6 ± 3.4 years).

RESULTS

Compared with control subjects, children with SCD had a significantly smaller upper airway (2.8 ± 1.2 cm(3) vs 3.7 ± 1.6 cm(3), P < .01), and significantly larger adenoid (8.4 ± 4.1 cm(3) vs 6.0 ± 2.2 cm(3), P < .01), tonsils (7.0 ± 4.3 cm(3) vs 5.1 ± 1.9 cm(3), P < .01), retropharyngeal nodes (3.0 ± 1.9 cm(3) vs 2.2 ± 0.9 cm(3), P < .05), and deep cervical nodes (15.7 ± 5.7 cm(3) vs 12.7 ± 4.0 cm(3), P < .05). Polysomnography showed that 19.4% (seven of 36) of children with SCD had OSAS compared with 0% (zero of 20) of control subjects (P < .05) and that in children with SCD the apnea-hypopnea index correlated positively with upper airway lymphoid tissues size (r = 0.57, P < 001). In addition, children with SCD had lower arterial oxygen saturation nadir (84.3% ± 12.3% vs 91.2% ± 4.2%, P < .05), increased peak end-tidal CO(2) (53.4 ± 8.5 mm Hg vs 42.3 ± 5.3 mm Hg, P < .001), and increased arousals (13.7 ± 4.7 events/h vs 10.8 ± 3.8 events/h, P < .05).

CONCLUSIONS

Children with SCD have reduced upper airway size due to overgrowth of the surrounding lymphoid tissues, which may explain their predisposition to OSAS.

ACSM and CHAMP summit on sickle cell trait: mitigating risks for warfighters and athletes

INTRODUCTION

An estimated 300 million people worldwide have sickle cell trait (SCT). Although largely benign, SCT has been associated with exertional rhabdomyolysis and exercise-related sudden death in warfighters/athletes (WA). The National Collegiate Athletic Association's policy to confirm a student athlete's SCT status during their preparticipation medical examination prompted reaction from some organizations regarding the rationale and ethical justification of the policy.

METHODS

On September 26 and 27, 2011, a summit, composed of military and civilian experts in sports medicine and SCT, was convened at the Uniformed Services University in Bethesda, MD. The expert panel was charged with two objectives: 1) to provide specific recommendations to further mitigate the apparent risk with strenuous exercise in WA with SCT and 2) to develop clinical guidelines to identify, treat, and return to duty/play WA suspected to have incurred nonfatal sickle cell collapse.

RESULTS

New terminology is introduced, areas of current controversy are explored, consensus recommendations for mitigating risk and managing the WA with SCT are reviewed, and important areas for future research are identified.

CONCLUSION

Further research is needed before conclusions can be drawn regarding the etiology of the increased death rate observed in WA with SCT, and the possibility exists that SCT is a surrogate for as yet another contributing factor for the unexplained deaths.

No improvement in suboptimal vitamin A status with a randomized, double-blind, placebo-controlled trial of vitamin A supplementation in children with sickle cell disease

BACKGROUND

Suboptimal vitamin A status is prevalent in children with type SS sickle cell disease (SCD-SS) and is associated with hospitalizations and poor growth and hematologic status. The supplemental vitamin A dose that optimizes suboptimal vitamin A status in this population is unknown.

OBJECTIVE

The efficacy of Recommended Dietary Allowance (RDA) doses (based on age and sex) of vitamin A (300, 400, or 600 μg retinyl palmitate/d) or vitamin A + zinc (10 or 20 mg zinc sulfate/d) compared with placebo to optimize vitamin A status was assessed in children aged 2.0-12.9 y with SCD-SS and a suboptimal baseline serum retinol concentration (<30 μg/dL).

DESIGN

In this randomized, double-blind, placebo-controlled trial, vitamin A status (serum retinol, prealbumin, retinol-binding protein, and relative-dose-response test) and disease-related illness events were assessed.

RESULTS

Twelve months of vitamin A supplementation at the doses recommended for healthy US children (based on age and sex) failed to improve serum retinol values in either group (vitamin A: n = 23; vitamin A + zinc: n = 18) compared with placebo (n = 21). By 12 mo, the increase (±SD) in serum retinol (3.6 ± 2.8 μg/dL) in those taking 600 μg vitamin A/d was significantly different from the decrease (±SD; -2.8 ± 2.4 μg/dL) in those taking 300 μg/d, which possibly suggests a dose-response relation (P < 0.05) with RDA doses.

CONCLUSIONS

Compared with placebo, 12 mo of vitamin A supplementation at the RDA for healthy children did not improve serum retinol values in children with SCD-SS, which possibly suggests that higher doses are needed. However, the existence of alternative conclusions emphasizes the need for future research.

Sickle cell disease in children: accuracy of imaging transcranial Doppler ultrasonography in detection of intracranial arterial stenosis

This study aimed to determine the accuracy of imaging transcranial Doppler sonography in detection of intracranial arterial stenosis in children with sickle cell disease using three-dimensional MR angiography as a reference standard. Sixty-one children (mean age 102±39 months, 30 males), who had no history of overt stroke, and were classified as at lowest risk of stroke by mean flow velocity criterion <170 cm/s, underwent conventional and imaging transcranial Doppler ultrasonographic examinations. We employed the area under the receiver operating characteristic curve (AUC) to determine the accuracy of flow velocity measurements obtained with imaging ultrasonography with and without correction for the angle of insonation as well as with conventional ultrasonography. We also established the most efficacious velocity thresholds for detection of the stenosis. We found ten intracranial stenoses in six patients on MR angiography, but we calculated AUC only for detection of stenosis (n=6) of the left intracranial internal carotid artery. The accuracy of flow velocity with angle correction was lower than the accuracy of velocity without angle correction (AUC=0.73, 95% CI, 0.53-0.93 versus AUC=0.87, 95% CI, 0.74-1.00; p=0.017). The accuracy of flow velocity obtained with conventional ultrasonography (AUC=0.82, 95% CI, 0.67-0.97) was not different from the accuracy of flow velocities obtained with imaging ultrasonography. We found that the threshold of 165 cm/s of mean velocity without angle correction is associated with highest efficiency for imaging (92%) and conventional ultrasonography (90%). Velocity measurements without angle-correction provide good accuracy in detection of stenosis of the terminal internal carotid artery, whereas angle-corrected velocities have lower accuracy.

Non-invasive measurements of carboxyhemoglobin and methemoglobin in children with sickle cell disease

Assessment of oxyhemoglobin saturation in patients with sickle cell disease (SCD) is vital for prompt recognition of hypoxemia. The accuracy of pulse oximeter measurements of blood oxygenation in SCD patients is variable, partially due to carboxyhemoglobin (COHb) and methemoglobin (MetHb), which decrease the oxygen content of blood. This study evaluated the accuracy and reliability of a non-invasive pulse co-oximeter in measuring COHb and MetHb percentages (SpCO and SpMet) in children with SCD. We hypothesized that measurements of COHb and MetHb by non-invasive pulse co-oximetry agree within acceptable clinical accuracy with those made by invasive whole blood co-oximetry. Fifty children with SCD-SS underwent pulse co-oximetry and blood co-oximetry while breathing room air. Non-invasive COHb and MetHb readings were compared to the corresponding blood measurements. The pulse co-oximeter bias was 0.1% for COHb and -0.22% for MetHb. The precision of the measured SpCO was ± 2.1% within a COHb range of 0.4-6.1%, and the precision of the measured SpMet was ± 0.33% within a MetHb range of 0.1-1.1%. Non-invasive pulse co-oximetry was useful in measuring COHb and MetHb levels in children with SCD. Although the non-invasive technique slightly overestimated the invasive COHb measurements and slightly underestimated the invasive MetHb measurements, there was close agreement between the two methods.

Capturing PLMS and their variability in children with sickle cell disease: does ankle activity monitoring measure up to polysomnography?

OBJECTIVES

To test agreement and define differences in periodic limb movements in sleep (PLMS) measured by polysomnography and an ankle activity monitor, and to describe PLMS variability across nights, feasibility of home monitoring, and correlates of PLMS in children with sickle cell disease (SCD).

METHODS

Twenty children with SCD and restless legs syndrome (RLS) symptoms or polysomnography-documented PLMS underwent concurrent attended polysomnography and ankle activity monitoring over one to two nights and home activity monitoring for three nights. Serum iron and ferritin were measured pre- and post-polysomnography.

RESULTS

Adequate sensitivity (1.00), specificity (0.69), and mean bias (5.0±7.4 PLMS/h) for identifying elevated PLMS by activity monitor were obtained when scoring the period from sleep onset to offset rather than time in bed per manufacturer recommendation, and using a cut-point of 10 PLMS/h. Compared to activity monitor, only polysomnographic PLMS demonstrated periodicity, at inter-movement intervals (IMI) 20-35 s; the activity monitor overscored PLMS at the beginning and end of sleep and at shorter IMI (5-15s; p≤0.003), suggesting misclassification of nonperiodic leg movements as PLMS by activity monitor. PLMS varied across four nights by 16.1±13.4 PLMS/h. Post-polysomnography ferritin was associated (positively) with PLMS (p=0.034); RLS symptoms were not.

CONCLUSIONS

Ankle activity monitoring is a valid screening measure for PLMS in children with SCD and can readily be performed at home. Interpretation should incorporate a threshold for elevated PLMS of 10/h and scoring from sleep onset to offset, which could be identified with concurrent wrist actigraphy, to better account for true PLMS.

Association of Pulsatility Index in the Middle Cerebral Artery with Intelligence Quotient in Children with Sickle Cell Disease

The aim of this study was to explore whether intellectual performance in children with Sickle Cell Disease and with low risk of stroke as determined with conventional transcranial Doppler ultrasonography (TCD) criteria was associated with hemodynamic parameters in imaging TCD, when controlling for hematological and socio-economical variables and presence of silent infarcts. We performed neuropsychological testing with Kaufman Brief Intelligence Test (K-BIT-IQ) and imaging TCD examinations to measure blood flow velocities and pulsatility indexes (PI) in the middle cerebral arteries (MCA) In 46 children with homozygous HbSS (mean age 108±34 months, range limits: 47–166 months; 24 females), without a history of stroke or transient ischemic attack, with no stenosis on magnetic resonance angiography and with velocities below 170 cm/s in screening conventional TCD. Mean K-BIT IQ Composite and Vocabulary scores (91±13 and 86±14 respectively) were significantly below the average scores of 100 for the age-matched population (one sample t-test=5.21, p<0.001). Using univariate and multivariate regression models, we found that lower PI in the right MCA was associated with lower K-BIT-IQ Composite and Vocabulary scores. Furthermore, we found that interhemispheric differences in PIs were even more strongly associated with neuropsychological performance, whereas flow velocities were not associated with the K-BIT-IQ score. Using a model of chronic anemia, we found that cognitive functioning was associated with cerebral hemodynamics.

Concerted global effort to combat sickle cell disease: the first global congress on sickle cell disease in Accra, Ghana

The First Global Congress on Sickle Cell Disease was held in Accra, Ghana, on July 20-23, 2010, to commemorate 100 years since the first published report of sickle cell disease (SCD). The idea of the Global Congress was conceived following the 2007 meeting in Nicosia, Cyprus, jointly organized by the WHO and the Thalassaemia International Federation (TIF), which recommended that groups working in SCD around the world needed to consolidate efforts into a stronger and more unified umbrella organization. The need for a united global effort received further endorsements at the 2009 International Symposium and Workshop held in Cotonou, Benin, and the 2009 inaugural commemoration of World Sickle Cell Disease Awareness Day, UN Headquarters, New York, New York. The overall goals of the Global Congress were to promote international cooperation and foster collaboration in advancing clinical care and furthering basic and applied research in SCD. Issues covered at the conference included health education, psychosocial needs, public health, medical care, research, program development, and development of international community-based organizations. The Congress participants included medical and research scientists, public health officials, community-based SCD organizations, other nongovernmental organizations, and people with SCD and their families. The Congress concluded with a call on patients and families affected by SCD, as well as advocacy groups, healthcare professionals, scientists, and national governments working to combat SCD to endorse the formation of the World Sickle Cell Disease Federation.

Periodic limb movements and disrupted sleep in children with sickle cell disease

STUDY OBJECTIVES

To describe the rate, distribution and correlates of periodic limb movements in sleep (PLMS) in children with sickle cell disease (SCD).

DESIGN

Prospective, cross-sectional.

SETTING

Hospital-based sleep laboratory.

PARTICIPANTS

Sixty-four children aged 2-18 years with SCD, hemoglobin SS-type who had an overnight polysomnogram and a parent-completed Pediatric Sleep Questionnaire. Mean age was 8.4 years (SD 4.8); 50% were male.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

The mean PLMS index was 3.7 (6.6) and ranged from 0 to 31.8, with 23.4% of the sample having PLMS ≥ 5/h. Sleep efficiency was decreased (P = 0.03), and the total arousal index (P = 0.003) and PLMS arousal index (P < 0.001) were increased in children with PLMS ≥ 5/h compared to those with PLMS < 5/h. PLMS were most frequent in NREM stage 2 sleep and during the fourth hour of sleep. Inter-movement interval duration peaked at 25-30 s. "Growing pains worst in bed" or "restlessness of the legs", suggesting restless legs syndrome (RLS), were reported in 12.5% of the total sample and were more common in children with elevated PLMS. A PLMS score for identifying elevated PLMS in children, based on items from the Pediatric Sleep Questionnaire, did not significantly predict PLMS ≥ 5/h.

CONCLUSIONS

Elevated PLMS are common in children with SCD and are associated with sleep disruption and symptoms of RLS. Future research into the time structure of PLMS, their causes and consequences, and development of a disease-specific sleep disorders screening questionnaire, is needed in children with SCD.

Sickle cell disease: reference values and interhemispheric differences of nonimaging transcranial Doppler blood flow parameters

BACKGROUND AND PURPOSE

TCD screening is widely used to identify children with SCD at high risk of stroke. Those with high mean flow velocities in major brain arteries have increased risk of stroke. Thus, our aim was to establish reference values of interhemispheric differences and ratios of blood flow Doppler parameters in the tICA, MCA, and ACA as determined by conventional TCD in children with sickle cell anemia.

MATERIALS AND METHODS

Reference limits of blood flow parameters were established on the basis of a consecutive cohort of 56 children (mean age, 100 ± 40 months; range, 29-180 months; 30 females) free of neurologic deficits and intracranial stenosis detectable by MRA, with blood flow velocities <170 cm/s by conventional TCD. Reference limits were estimated by using tolerance intervals, within which are included with a probability of .90 of all possible data values from 95% of a population.

RESULTS

Average peak systolic velocities were significantly higher in the right hemisphere in the MCA and ACA (185 ± 28 cm/s versus 179 ± 27 and 152 ± 30 cm/s versus 143 ± 34 cm/s respectively). Reference limits for left-to-right differences in the mean flow velocities were the following: -43 to 33 cm/s for the MCA; -49 to 38 cm/s for the ACA, and -38 to 34 cm/s for the tICA, respectively. Respective reference limits for left-to-right velocity ratios were the following: 0.72 to 1.25 cm/s for the MCA; 0.62 to 1.39 cm/s for the ACA, and 0.69 to 1.27 cm/s for the tICA. Flow velocities in major arteries were inversely related to age and Hct or Hgb.

CONCLUSIONS

The study provides reference intervals of TCD flow velocities and their interhemispheric differences and ratios that may be helpful in identification of intracranial arterial stenosis in children with SCD undergoing sonographic screening for stroke prevention.

Upper airway genioglossal activity in children with sickle cell disease

STUDY OBJECTIVES

The prevalence of obstructive sleep apnea syndrome (OSAS) in sickle cell disease (SCD) has been reported to be higher than that in the general pediatric population. However, not all subjects with SCD develop OSAS. We hypothesized that SCD patients with OSAS have a blunted neuromuscular response to subatmospheric pressure loads during sleep, making them more likely to develop upper airway collapse.

DESIGN

Subjects with SCD with and without OSAS underwent pressure-flow measurements during sleep using intraoral surface electrodes to measure genioglossal EMG (EMGgg). Two techniques were applied to decrease the nasal pressure (P(N)) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway. The area under the curve of the inspiratory EMGgg moving time average was analyzed. EMGgg activity was expressed as a percentage of baseline. Changes in EMGgg in response to decrements in nasal pressure were expressed as the slope of the EMGgg vs. nasal pressure (slope of EMGgg-P(N)).

SETTING

Sleep laboratory.

PARTICIPANTS

4 children with SCD and OSAS and 18 children with SCD but without OSAS.

RESULTS

THE MAJOR FINDINGS OF THIS STUDY WERE: (1) using the activated but not the hypotonic technique, the slope of EMGgg-P(N) was more negative in SCD controls than SCD OSAS; (2) the slope of EMGgg-P(N) was significantly lower using the activated technique compared to the hypotonic technique in SCD controls only; (3) similarly, the critical closing pressure, Pcrit, was more negative using the activated technique than the hypotonic technique in SCD controls but not in SCD OSAS.

CONCLUSION

This preliminary study has shown that children with SCD but without OSAS have more prominent upper airway reflexes than children with SCD and OSAS.

Transfusion and chelation practices in sickle cell disease: a regional perspective

Although most common in tropical regions, population migration has meant that sickle cell disease is now one of the most prevalent genetic diseases worldwide. The issues and challenges faced by physicians and patients have been discussed by an international group of experts representing 4 key regions: the USA, Europe, Latin America, and the Middle East/Africa. Conclusive evidence to support the use of transfusion therapy for the prevention of stroke has resulted in key changes to patient management in all regions, and increasing numbers of patients are benefiting from this management approach. However, it is apparent that transfusion therapy is still under-utilized, largely due to concerns over iron overload, alloimmunization, limited blood supplies, and, sometimes, due to parental refusal. Once transfused, assessment and management of body iron levels can be poor, particularly in patients who are intermittently transfused. Compliance with chelation therapy regimens is a significant challenge, but new therapeutic options are likely to overcome some of the current barriers. Key requirements in all regions were considered to be the following: to provide greater physician, patient, and family education; to ensure effective transition from pediatric to adult care; and to establish national guidelines in order to ensure best practice is consistently applied.

Approaches to transfusion therapy and iron overload in patients with sickle cell disease: results of an international survey

To gain an insight into current transfusion and chelation practice in patients with sickle cell disease (SCD), a survey of international experts has been conducted. The findings demonstrate that general utilization of transfusion therapy is low, the primary barrier to treatment being concerns over resultant iron overload and the subsequent need for iron chelation therapy. Where patients were transfused, many physicians indicated that a high proportion of patients had hemosiderosis. As evidence suggests more patients with SCD could benefit from regular transfusion therapy, it is apparent that greater awareness of the need to monitor and treat iron overload in transfused patients is required.

Sickle cell disease and transcranial Doppler imaging: inter-hemispheric differences in blood flow Doppler parameters

BACKGROUND AND PURPOSE

to establish reference values of interhemispheric differences and ratios of blood flow Doppler parameters in the terminal internal carotid artery, middle cerebral artery, and anterior cerebral artery in children with sickle cell anemia.

METHODS

fifty-seven out of 74 recruited children (mean age, 7.8 ± 3.4 years; range limits, 3-14 years), who were free of neurological deficits and intracranial narrowing detectable by MRA and had flow velocities <170 cm/s by conventional transcranial Doppler ultrasound, underwent transcranial color-coded duplex ultrasonography. Reference limits of flow parameters corrected and uncorrected for the angle of insonation were estimated using tolerance intervals, with P=0.90 for all possible data values from 95% of a population.

RESULTS

reference limits for left-to-right differences in cm/s in the mean angle-corrected and uncorrected flow velocities were -56 to 53 and -72 to 75 for middle cerebral artery, -49 to 57 and -81 to 91 for anterior cerebral artery, and -55 to 64 and -73 to 78 for terminal internal carotid artery, respectively. Respective reference limits for left-to-right velocity ratios were 0.31 to 1.84 and 0.38 to 1.75 for middle cerebral artery, 0.48 to 2.99 and 0.46 to 2.89 for anterior cerebral artery, and 0.61 to 2.56 and 0.56 to 2.23 for terminal internal carotid artery.

CONCLUSIONS

the study provides reference limits of interhemispheric differences and ratios of blood flow Doppler parameters that may be helpful in identification of intracranial arterial narrowing in children with sickle cell disease undergoing ultrasound screening for stroke prevention.

Pulmonary, gonadal, and central nervous system status after bone marrow transplantation for sickle cell disease

We conducted a prospective, multicenter investigation of human-leukocyte antigen (HLA) identical sibling bone marrow transplantation (BMT) in children with severe sickle cell disease (SCD) between 1991 and 2000. To determine if children were protected from complications of SCD after successful BMT, we extended our initial study of BMT for SCD to conduct assessments of the central nervous system (CNS) and of pulmonary function 2 or more years after transplantation. In addition, the impact on gonadal function was studied. After BMT, patients with stroke who had stable engraftment of donor cells experienced no subsequent stroke events after BMT, and brain magnetic resonance imaging (MRI) exams demonstrated stable or improved appearance. However, 2 patients with graft rejection had a second stroke after BMT. After transplantation, most patients also had unchanged or improved pulmonary function. Among the 11 patients who had restrictive lung changes at baseline, 5 were improved and 6 had persistent restrictive disease after BMT. Of the 2 patients who had obstructive changes at baseline, 1 improved and 1 had worsened obstructive disease after BMT. There was, however, significant gonadal toxicity after BMT, particularly among female recipients. In summary, individuals who had stable donor engraftment did not experience sickle-related complications after BMT, and were protected from progressive CNS and pulmonary disease.

Silent infarcts in young children with sickle cell disease

Silent infarcts have been reported most commonly in school-aged children with homozygous sickle cell disease (SCD-SS) and are associated with neurocognitive deficits. However, the prevalence of silent infarcts in younger children with SCD-SS is not well defined. In this retrospective study, brain magnetic resonance imaging and angiography (MRI/A) studies performed before 6 years of age in a cohort of children with SCD-SS were analysed and the prevalence of abnormalities was calculated. Clinical and laboratory parameters were compared between the groups with and without silent infarcts. Sixty-eight of 96 children in the cohort had brain MRI/A performed prior to age 6 years. Of the 65 who were neurologically asymptomatic, 18 (27.7%, 95% CI 17.3-40.2%) had silent infarcts (mean age 3.7 +/- 1.1 years, range 1.3-5.9 years). Factors associated with silent infarcts included cerebral vessel stensosis by magnetic resonance angiography, lower rates of vaso-occlusive pain and acute chest syndrome and lower haemoglobin levels. The prevalence of silent infarcts in young children with SCD-SS is similar to that of older children and anaemia and severe vasculopathy may be risk factors.

Markers of bone turnover are associated with growth and development in young subjects with sickle cell anemia

Children with sickle cell anemia (SCA) have low bone mass though bone turnover has not been well described. In this study, growth and pubertal development were assessed twice, 1 year apart, in 80 young subjects with type-SS SCA, while whole body bone mineral content (BMC) and density where measured in a subset (n = 46). Markers of bone turnover were measured at the second visit. Bone formation (alkaline phosphatase) was elevated, whereas bone resorption (deoxypyridinoline) was decreased compared to published data in healthy children. Markers of bone turnover correlated with growth velocity and pubertal development but not with changes in bone mass.

Headache in children with sickle cell disease: prevalence and associated factors

OBJECTIVE

To compare the prevalence of frequent headache in children with sickle cell disease (SCD) to that of black control subjects and to assess factors associated with headache in SCD.

STUDY DESIGN

In this cross-sectional study, a headache questionnaire was administered to subjects with SCD and black control subjects. Subjects answered supplementary questions about SCD complications. Clinical and radiographic information were abstracted from medical charts for subjects with SCD.

RESULTS

Children (n = 241) with SCD and 141 control subjects were studied; 32.4% (95% CI 26.5%-38.7%) of subjects with SCD reported having headaches at least weekly, similar to control subjects at 27% (95% CI 19.8%-35.1%, P = NS); however, in children <13 years, headache was more common in subjects with SCD than in control subjects (24% vs 9.7%, P = .013). The prevalence of headache was similar among the different SCD genotypes. Factors associated with frequent headaches in subjects with SCD included older age, frequent vaso-occlusive pain episodes, symptoms of obstructive sleep apnea, and cerebral vessel stenosis detected by magnetic resonance angiography.

CONCLUSION

The prevalence of headaches in children with SCD is similar to the general population; however, younger children with SCD report headaches more frequently than control subjects. The cause of headache is likely multifactorial, and SCD-specific factors may contribute.

Adequacy of Dietary Intake Declines with Age in Children with Sickle Cell Disease

Dietary intake (24-hour recall) was evaluated prospectively over four annual visits in 97 children and adolescents (53 female), aged 1.5 to 18.7 years, with sickle cell disease, type SS. Macro- and micronutrient intakes were compared to Dietary Reference Intakes (DRI) and expressed as %DRI. z scores for height, weight, and body mass index were calculated to assess growth status. Both t tests and Mann-Whitney U tests were used for year 1 comparisons, and longitudinal mixed effects analysis was used for the longitudinal data. Intake of vitamins E and D, folate, calcium, and fiber as %DRI was low for children of all ages. Intake of protein, vitamin C, riboflavin, vitamin B-12, and magnesium was lower by at least 28% DRI in the oldest (aged 14 to 18 years) compared to the youngest children (aged 1 to 3 years), and intake of vitamin A, magnesium, and phosphorus was suboptimal in children older than 9 years. After adjusting for initial age and sex, intake of riboflavin, zinc, calcium, magnesium, and phosphorus declined steeply (8% to 16% DRI annually) across the 3 years. Weight and body mass index z scores also declined over time. Dietary intake was particularly poor in adolescents. Efforts are needed to ensure dietary adequacy in children with sickle cell disease, type SS and to understand the etiology of poor dietary intake.

Effects of delayed pubertal development, nutritional status, and disease severity on longitudinal patterns of growth failure in children with sickle cell disease

Previous studies of children with sickle cell disease (SCD) reported poor growth and delayed maturation. However, the prevalence, magnitude, and correlates of suboptimal growth remain poorly understood. A prospective longitudinal study was undertaken to determine the effects of disease severity and nutritional status on growth, an indicator of childhood well-being. Children, birth to 18 y of age, with SCD-SS were evaluated annually for 4 y. Growth, nutritional status, skeletal and sexual maturation, disease severity, dietary intake, and maternal education were assessed. In this sample of 148 children (78 females), growth in height, weight, or body mass index declined in 84% of subjects; 38% fell below the 5th percentile in one or more measures. Puberty was delayed 1 to 2 y, and median age at menarche was 13.2 y. Skeletal age was delayed by 0.7 +/- 1.4 y overall and by 1.3 +/- 1.5 y in children 10 to 15 y old. Height status declined over time and was positively associated with advancing puberty and hematological measures in girls, and nutritional status in girls and boys. Growth failure and maturational delay remain significant chronic problems in children with SCD-SS and are related to potentially modifiable factors such as nutritional status.

Effect of myeloablative bone marrow transplantation on growth in children with sickle cell anaemia: results of the multicenter study of haematopoietic cell transplantation for sickle cell anaemia

Although haematopoietic cell transplantation (HCT) is curative for sickle cell anaemia (SCA), concerns about its short- and long-term toxicities limit its application. A potential toxicity is an adverse effect on growth. To identify an HCT growth effect, serial height and weight measurements from 53 children and adolescents with SCA after receiving a transplant were compared to historical controls. Hierarchical Linear Models for longitudinal data were used for analysis. In general growth was not impaired by HCT for SCA in young children; however, diminished growth may occur if HCT is carried out near or during the adolescent growth spurt.

Prolongation of the prothrombin time and activated partial thromboplastin time in children with sickle cell disease

BACKGROUND

Patients with sickle cell disease (SCD) have high rates of perioperative complications, including bleeding 1,2.

PROCEDURES

We conducted a retrospective review of pre-operative coagulation studies in pediatric patients with SCD followed by a prospective study of 100 well children with SCD to determine the prevalence of abnormal coagulation screening tests, and to evaluate potential etiologies.

RESULTS

In the retrospective study, 32/84 (38.1%) had a prolonged prothrombin time (PT), compared to 8/100 in the prospective study. Prolongations of the activated partial thromboplastin time (aPTT) were less common. Children in the prospective study with prolonged PTs had significantly lower levels of Factor V and VII compared to those with normal PTs. Factor VII levels were <50% in 4/8 with long PTs, compared to 3/92 with normal PTs, P=0.001. Though retrospectively, several patients had normalization of their PT with vitamin K, there was no laboratory evidence of vitamin K deficiency in the prospective study. In the retrospective analysis, six of seven children who had pre-operative coagulation studies and significant intraoperative blood loss had prolonged PTs (P=0.04).

CONCLUSIONS

Children with SCD admitted for surgical procedures were more likely to have prolonged PTs than those tested at a well visit. There was intra-patient variability in coagulation studies that may be related to clinical status, hepatocellular dysfunction, and/or increased clotting factor consumption. Future well-designed prospective studies to determine whether abnormal coagulation studies are associated with an increased risk of perioperative bleeding in children with SCD are necessary.

Modulation of erythrocyte arginase activity in sickle cell disease patients during hydroxyurea therapy

An elevated erythrocyte arginase activity with a corresponding decrease in nitric oxide (NO) level has been implicated in the pathophysiology of sickle cell disease (SCD). Recent studies have shown that hydroxyurea (HU) increases the production of NO, which increases the soluble guanylate cyclase activity and fetal haemoglobin (HbF) synthesis. To study the effects of HU on the arginase and nitric oxide synthase (NOS) activities in SCD patients, we compared levels of arginase activity and NO metabolites in red blood cells and plasma, respectively, from 23 patients with SCD (HbSS) receiving HU therapy, with those of 12 SCD patients not receiving HU treatment. Patients on HU therapy showed significantly lower arginase activity than that of HbSS patients not on HU therapy (1.36+/-0.2 U/10(8) cells vs. 3.31+/-0.29 U/10(8) cells). NOS activity was higher in patients on HU therapy than in untreated patients (0.72+/-0.4 nmol/ml/min vs. 0.35+/-0.15 nmol/ml/min, P<0.05). Among the HU-treated patients, the decreased level of arginase activity correlated (r=0.71) with HbF level as well as the mean corpuscular haemoglobin content. These data suggest that one of the beneficial effects of HU in vivo may involve the regulation of arginase activity and a concomitant induction of NOS activity, which may lead to an increased production of NO. The outcome of this study may lead to the development of improved NO-based treatments for SCD.