Primary prevention of stroke in children with sickle cell anemia in sub-Saharan Africa: rationale and design of phase III randomized clinical trial

Models of care for sickle cell disease in low-income and lower-middle-income countries: a scoping review

Sickle cell disease has a growing global burden falling primarily on low-income countries (LICs) and lower-middle-income countries (LMICs) where comprehensive care is often insufficient, particularly in rural areas. Integrated care models might be beneficial for improving access to care in areas with human resource and infrastructure constraints. As part of the Centre for Integration Science's ongoing efforts to define, systematise, and implement integrated care delivery models for non-communicable diseases (NCDs), this Review explores models of care for sickle cell disease in LICs and LMICs. We identified 99 models from 136 studies, primarily done in tertiary, urban facilities in LMICs. Except for two models of integrated care for concurrent treatment of other conditions, sickle cell disease care was mostly provided in specialised clinics, which are low in number and accessibility. The scarcity of published evidence of models of care for sickle cell disease and integrated care in rural settings of LICs and LMICs shows a need to implement more integrated models to improve access, particularly in rural areas. PEN-Plus, a model of decentralised, integrated care for severe chronic non-communicable diseases, provides an approach to service integration that could fill gaps in access to comprehensive sickle cell disease care in LICs and LMICs.

Risk factors in underweight older children with sickle cell anemia: a comparison of low- to high-income countries

Previously, we demonstrated that older children with sickle cell anemia (SCA) living in Nigeria are at increased risk of death if they are underweight (weight-for-age z score < -1). We now conducted a cross-sectional study in low- and high-income settings to determine the risk factors for being underweight a in children aged 5 to 12 years with SCA. The children from low- and high-income settings were eligible participants for the Primary Prevention of Stroke in Children with Sickle Cell Disease in Nigeria (SPRING; N = 928) and the Silent Cerebral Infarct (SIT, North America/Europe; N = 1093) trials, respectively. The median age in the SPRING and SIT cohorts was 8.1 and 8.5 years, respectively (P < .001). A total of 87.9% (n = 816) of participants in the SPRING trial (low-income) met the study criteria for being underweight (weight-for-age z score < -1), and 22.7% (n = 211) for severely underweight (weight-for-age z score < -3), significantly higher than the SIT (high-income) cohort at 25.7% underweight (n = 281) and 0.7% severely underweight (n = 8; P < .001 for both comparisons). In the combined cohort, older age (odds ratio [OR], 1.24; P < .001) and lower hemoglobin level (OR, 0.67; P < .001) were associated with being underweight. Age and hemoglobin level remained statistically significant in separate models for the SPRING and SIT cohorts. Older age and lower hemoglobin levels in children aged 5 to 12 years with SCA are associated with being underweight in low- and high-income settings.

Feasibility trial for the management of severe acute malnutrition in older children with sickle cell anemia in Nigeria

Children with sickle cell anemia (SCA) living in Nigeria are at an increased risk of malnutrition, which contributes to increased morbidity and mortality. However, evidence-based guidelines for managing malnutrition in children with SCA are lacking. To address this gap, we conducted a multicenter, randomized controlled feasibility trial to assess the feasibility and safety of treating children with SCA aged from 5 to 12 years and having uncomplicated severe acute malnutrition (body mass index z score of <-3.0). Children with SCA and uncomplicated severe acute malnutrition were randomly allocated to receive supplemental ready-to-use therapeutic food (RUTF) with or without moderate-dose hydroxyurea therapy (20 mg/kg per day). Over a 6-month enrollment period, 3190 children aged from 5 to 12 years with SCA were evaluated for eligibility, and 110 of 111 children who were eligible were enrolled. During the 12-week trial, no participants withdrew or missed visits. One participant died of unrelated causes. Adherence was high for hydroxyurea (94%, based on pill counts) and RUTF (100%, based on the number of empty sachets returned). No refeeding syndrome event or hydroxyurea-related myelosuppression occurred. At the end of the trial, the mean change in body mass index z score was 0.49 (standard deviation = 0.53), and 39% of participants improved their body mass index z score to ≥-3.0. Our findings demonstrate the feasibility, safety, and potential of outpatient treatment for uncomplicated severe acute malnutrition in children with SCA aged from 5 to 12 years in a low-resource setting. However, RUTF sharing with household and community members potentially confounded the response to malnutrition treatment. This trial was registered at clinicaltrials.gov as #NCT03634488.

Management of Pediatric Stroke - Challenges and Perspectives from Resource-limited Settings

Childhood stroke is not as common as adult stroke, but it is underrecognized the world over. Diagnosis is often delayed due to lack of awareness not only by the lay public but also by emergency and front-line health care workers. Despite the relative rarity of childhood stroke, the impact on morbidity, mortality and the economic burden for families and society is high, especially in poorly resourced settings. The risk factors for stroke in children differ from the adult population where lifestyle factors play a more important role. The developmental aspects of the pediatric cerebral vasculature and hematological maturational biology affects the clinical presentation, investigation, management and outcomes of childhood stroke in a different way compared to adults. The management of childhood stroke is currently based on expert guidelines and evidence extrapolated from adult studies. Hyperacute therapies that have revolutionized the treatment of stroke in adults cannot be easily applied to children at this stage due to the diagnostic delays, diverse risk factors and developmental considerations mentioned above. Much has been achieved in the understanding of genetic, acquired, preventable and recurrent stroke risk factors in the past decade through international collaborative efforts like the International Pediatric Stroke Study. Evidence for the prevention and treatment of childhood stroke remains elusive. Even more elusive are relevant and achievable management guidelines for pediatric stroke in resource-limited settings. This narrative review focusses on the current management practices globally, emphasizing the challenges, and gaps in knowledge of pediatric stroke in low- and middle-income countries and other areas with limited resources. Priorities and some potential solutions at national and local level are suggested for these settings.

Hydroxyurea (hydroxycarbamide) for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and a reduced life expectancy. Hydroxyurea (hydroxycarbamide), an oral chemotherapeutic drug, ameliorates some of the clinical problems of SCD, in particular that of pain, by raising foetal haemoglobin (HbF). This is an update of a previously published Cochrane Review.

OBJECTIVES

The aims of this review are to determine through a review of randomised or quasi-randomised studies whether the use of hydroxyurea in people with SCD alters the pattern of acute events, including pain; prevents, delays or reverses organ dysfunction; alters mortality and quality of life; or is associated with adverse effects. In addition, we hoped to assess whether the response to hydroxyurea in SCD varies with the type of SCD, age of the individual, duration and dose of treatment, and healthcare setting.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Haemoglobinopathies Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries. The date of the most recent search was 17 February 2022.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials (RCTs and quasi-RCTs), of one month or longer, comparing hydroxyurea with placebo or standard therapy in people  with SCD.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction, assessed the risk of bias and assessed the quality of the evidence using GRADE.

MAIN RESULTS

We included nine RCTs recruiting 1104 adults and children with SCD (haemoglobin SS (HbSS), haemoglobin SC (HbSC) or haemoglobin Sβºthalassaemia (HbSβºthal) genotypes). Studies lasted from six to 30 months. We judged the quality of the evidence for the first two comparisons below as moderate to low as the studies contributing to these comparisons were mostly large and well-designed (and at low risk of bias); however, the evidence was limited and imprecise for some outcomes such as quality of life, deaths during the studies and adverse events, and the results are applicable only to individuals with HbSS and HbSβºthal genotypes. We judged the quality of the evidence for the third and fourth comparisons to be very low due to the limited number of participants, the lack of statistical power (both studies were terminated early with approximately only 20% of their target sample size recruited) and the lack of applicability to all age groups and genotypes. Hydroxyurea versus placebo Five studies (784 adults and children with HbSS or HbSβºthal) compared hydroxyurea to placebo; four recruited individuals with only severe disease and one recruited individuals with all disease severities. Hydroxyurea probably improves pain alteration (using measures such as pain crisis frequency, duration, intensity, hospital admissions and opoid use) and life-threatening illness, but we found no difference in death rates (10 deaths occurred during the studies, but the rates did not differ by treatment group) (all moderate-quality evidence). Hydroxyurea may improve measures of HbF (low-quality evidence) and probably decreases neutrophil counts (moderate-quality evidence). There were no consistent differences in terms of quality of life and adverse events (including serious or life-threatening events) (low-quality evidence). There were fewer occurrences of acute chest syndrome and blood transfusions in the hydroxyurea groups.  Hydroxyurea and phlebotomy versus transfusion and chelation Two studies (254 children with HbSS or HbSβºthal also with risk of primary or secondary stroke) contributed to this comparison. There were no consistent differences in terms of pain alteration, death or adverse events (low-quality evidence) or life-threatening illness (moderate-quality evidence). Hydroxyurea with phlebotomy probably increased HbF and decreased neutrophil counts (moderate-quality evidence), but there were more occurrences of acute chest syndrome and infections. Quality of life was not reported. In the primary prevention study, no strokes occurred in either treatment group but in the secondary prevention study, seven strokes occurred in the hydroxyurea and phlebotomy group (none in the transfusion and chelation group) and the study was terminated early.  Hydroxyurea versus observation One study (22 children with HbSS or HbSβºthal also at risk of stoke) compared hydroxyurea to observation. Pain alteration and quality of life were not reported. There were no differences in life-threatening illness, death (no deaths reported in either group) or adverse events (very low-quality evidence). We are uncertain if hydroxyurea improves HbF or decreases neutrophil counts (very low-quality evidence). Treatment regimens with and without hydroxyurea One study (44 adults and children with HbSC) compared treatment regimens with and without hydroxyurea. Pain alteration, life-threatening illness and quality of life were not reported. There were no differences in death rates (no deaths reported in either group), adverse events or neutrophil levels (very low-quality evidence). We are uncertain if hydroxyurea improves HbF (very low-quality evidence).

AUTHORS' CONCLUSIONS

There is evidence to suggest that hydroxyurea may be effective in decreasing the frequency of pain episodes and other acute complications in adults and children with sickle cell anaemia of HbSS or HbSβºthal genotypes and in preventing life-threatening neurological events in those with sickle cell anaemia at risk of primary stroke by maintaining transcranial Doppler velocities. However, there is still insufficient evidence on the long-term benefits of hydroxyurea, particularly with regard to preventing chronic complications of SCD, or recommending a standard dose or dose escalation to maximum tolerated dose. There is also insufficient evidence about the long-term risks of hydroxyurea, including its effects on fertility and reproduction. Evidence is also limited on the effects of hydroxyurea on individuals with the HbSC genotype. Future studies should be designed to address such uncertainties.

Childhood stroke

Stroke is an important cause of neurological morbidity in children; most survivors have permanent neurological deficits that affect the remainder of their life. Stroke in childhood, the focus of this Primer, is distinguished from perinatal stroke, defined as stroke before 29 days of age, because of its unique pathogenesis reflecting the maternal-fetal unit. Although approximately 15% of strokes in adults are haemorrhagic, half of incident strokes in children are haemorrhagic and half are ischaemic. The causes of childhood stroke are distinct from those in adults. Urgent brain imaging is essential to confirm the stroke diagnosis and guide decisions about hyperacute therapies. Secondary stroke prevention strongly depends on the underlying aetiology. While the past decade has seen substantial advances in paediatric stroke research, the quality of evidence for interventions, such as the rapid reperfusion therapies that have revolutionized arterial ischaemic stroke care in adults, remains low. Substantial time delays in diagnosis and treatment continue to challenge best possible care. Effective primary stroke prevention strategies in children with sickle cell disease represent a major success, yet barriers to implementation persist. The multidisciplinary members of the International Pediatric Stroke Organization are coordinating global efforts to tackle these challenges and improve the outcomes in children with cerebrovascular disease.

Hydroxyurea for primary stroke prevention in children with sickle cell anaemia in Nigeria (SPRING): a double-blind, multicentre, randomised, phase 3 trial

BACKGROUND

In high-income countries, standard care for primary stroke prevention in children with sickle cell anaemia and abnormal transcranial Doppler velocities results in a 92% relative risk reduction of strokes but mandates initial monthly blood transfusion. In Africa, where regular blood transfusion is not feasible for most children, we tested the hypothesis that initial moderate-dose compared with low-dose hydroxyurea decreases the incidence of strokes for children with abnormal transcranial Doppler velocities.

METHODS

SPRING is a double-blind, parallel-group, randomised, controlled, phase 3 trial of children aged 5-12 years with sickle cell anaemia with abnormal transcranial Doppler velocities conducted at three teaching hospitals in Nigeria. For randomisation, we used a permuted block allocation scheme with block sizes of four, stratified by sex and site. Allocation was concealed from all but the pharmacists and statisticians. Participants were assigned in a 1:1 ratio to low-dose (10 mg/kg per day) or moderate-dose (20 mg/kg per day) oral hydroxyurea taken once daily with monthly clinical evaluation and laboratory monitoring. The primary outcome was initial stroke or transient ischaemic attack, centrally adjudicated. The secondary outcome was all-cause hospitalisation. We used the intention-to-treat population for data analysis. The trial was stopped early for futility after a planned minimum follow-up of 3·0 years to follow-up for participants. This trial was registered with ClinicalTrials.gov, number NCT02560935.

FINDINGS

Between Aug 2, 2016, and June 14, 2018, 220 participants (median age 7·2 years [IQR 5·5-8·9]; 114 [52%] female) were randomly allocated and followed for a median of 2·4 years (IQR 2·0-2·8). All participants were Nigerian and were from the following ethnic groups: 179 (82%) people were Hausa, 25 (11%) were Fulani, and 16 (7%) identified as another ethnicity. In the low-dose hydroxyurea group, three (3%) of 109 participants had strokes, with an incidence rate of 1·19 per 100 person-years and in the moderate-dose hydroxyurea group five (5%) of 111 had strokes with an incidence rate of 1·92 per 100 person-years (incidence rate ratio 0·62 [95% CI 0·10-3·20], p=0·77). The incidence rate ratio of hospitalisation for any reason was 1·71 (95% CI 1·15-2·57, p=0·0071), with higher incidence rates per 100 person-years in the low-dose group versus the moderate-dose group (27·43 vs 16·08). No participant had hydroxyurea treatment stopped for myelosuppression.

INTERPRETATION

Compared with low-dose hydroxyurea therapy, participants treated with moderate-dose hydroxyurea had no difference in the stroke incidence rate. However, secondary analyses suggest that the moderate-dose group could lower incidence rates for all-cause hospitalisations. These findings provide an evidence-based guideline for the use of low-dose hydroxyurea therapy for children with sickle cell anaemia at risk of stroke.

FUNDING

National Institute of Neurological Disorders and Stroke.

Capacity Building for Primary Stroke Prevention Teams in Children Living With Sickle Cell Anemia in Africa

BACKGROUND

Nigeria has the highest proportion of children with sickle cell anemia (SCA) globally; an estimated 150,000 infants with SCA are born annually. Primary stroke prevention in children with SCA must include Nigeria. We describe capacity-building strategies in conjunction with two National Institutes of Health-funded primary stroke prevention trials (a feasibility trial and phase III randomized controlled trial) with initial hydroxyurea treatment for children with SCA and abnormal transcranial Doppler (TCD) velocities in Nigeria. We anticipated challenges to conducting clinical trials in a low-resource setting with a local team that had not previously been involved in clinical research and sought a sustainable strategy for primary stroke prevention.

METHODS

This is a descriptive, prospective study of challenges, solutions, and research teams in two trials that enrolled a total of 679 children with SCA.

RESULTS

As part of the capacity-building component of the trials, over eight years, 23 research personnel (physicians, nurses, research coordinators, a statistician, and a pharmacist) completed a one-month research governance and ethics training program at Vanderbilt University Medical Center, USA. A lead research coordinator for each site completed the Society of Clinical Research Professionals certification. TCD machines were donated; radiologists and nonradiologists were trained and certified to perform TCD. A scalable E-prescription was implemented to track hydroxyurea treatment. We worked with regional government officials to support ongoing TCD-based screening and funding for hydroxyurea for children with SCA at a high risk of stroke.

CONCLUSIONS

Our trials and capacity building demonstrate a sustainable strategy to initiate and maintain pediatric SCA primary stroke prevention programs in Africa.

The V-RAMP Program: Building Research Administration and Management Capacity in Nigeria

The increasing volume and complexity of research activities in Nigeria necessitates urgent measures to improve research infrastructure in grants administration and management. The Vanderbilt-Nigeria Research Administration and Management Training Program (V-RAMP) seeks to build infrastructure capacity in research administration and management and research ethics at a major teaching hospital in Nigeria. We will perform a mixed methods needs assessment of the administrative and management environment and develop an action plan to address infrastructure needs, prioritize processes, and guide program implementation. We will capacitate a newly established Office of Research Administration and improve the knowledge and skills of research administrators and grant managers via short term in-person trainings in Nashville, Tennessee and in Kano, Nigeria and through remote learning opportunities. We will enhance local administrative efficiency and performance of research ethics operations through training and mentoring of members and staff of the ethics review committee. Systematic processes to streamline protocols, including a REDCap protocol tracking database and standard operating procedures in the responsible conduct of research and rigor and reproducibility will also be developed. V-RAMP will enable the creation of a high-quality research administration environment that is knowledgeable, efficient, and compliant regarding the fiscal, management and ethical standards of sponsored research.

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

Advances in neuroimaging to improve care in sickle cell disease

Sickle cell disease is associated with progressive and increased neurological morbidity throughout the lifespan. In people with sickle cell anaemia (the most common and severe type of sickle cell disease), silent cerebral infarcts are found in more than a third of adolescents by age 18 years and roughly half of young adults by age 30 years, many of whom have cognitive impairment despite having few or no conventional stroke risk factors. Common anatomical neuroimaging in individuals with sickle disease can assess structural brain injury, such as stroke and silent cerebral infarcts; however, emerging advanced neuroimaging methods can provide novel insights into the pathophysiology of sickle cell disease, including insights into the cerebral haemodynamic and metabolic contributors of neurological injury. Advanced neuroimaging methods, particularly methods that report on aberrant cerebral blood flow and oxygen delivery, have potential for triaging patients for appropriate disease-modifying or curative therapies before they have irreversible neurological injury, and for confirming the benefit of new therapies on brain health in clinical trials.