Primary stroke prevention in Nigerian children with sickle cell disease (SPIN): challenges of conducting a feasibility trial

BACKGROUND: The majority of children with sickle cell disease (SCD), approximately 75%, are born in sub-Saharan Africa. For children with elevated transcranial Doppler (TCD) velocity, regular blood transfusion therapy for primary stroke prevention is standard care in high income countries, but is not feasible in sub-Saharan Africa.PROCEDURE: In the first U.S. National Institute of Health (NIH) sponsored SCD clinical trial in sub-Saharan Africa, we describe the protocol and challenges unique to starting a clinical trial in this region. We are conducting a single arm pilot trial of hydroxyurea therapy in children with TCD velocity ≥200 cm/sec in the middle cerebral arteries. Eligible children will be placed on hydroxyurea (n = 40) and followed for 3 years at Aminu Kano Teaching Hospital, Nigeria. Adherence will be measured via the Morisky Scale and adverse events will be determined based on hospitalization.RESULTS: Originally, a randomized placebo trial was planned; however, placebo was not approved by the local Ethics Committee. Hence a single arm trial of hydroxyurea will be conducted and five controls per patient with normal TCD measurements will be followed to compare the rate of adverse events to those with abnormal TCD measurements taking hydroxyurea. Using non-NIH funding, over 9 months, multiple face-to-face investigator meetings were conducted to facilitate training.CONCLUSION: A hydroxyurea trial (NCT01801423) for children with SCD is feasible in sub-Saharan Africa; however, extensive training and resources are needed to build a global patient oriented multi-disciplinary research team with a common purpose.</p

Acceptability and safety of hydroxyurea for primary prevention of stroke in children with sickle cell disease in Nigeria

Background: Nigeria has the highest prevalence of sickle cell disease (SCD), a common cause of pediatric ischemic stroke. In sub-Saharan Africa monthly blood transfusions for primary stroke prevention carries risks; hydroxyurea (HU) may be an alternative. We conducted the first, US NIH funded, SCD feasibility trial in sub-Saharan Africa (5R21NS080639-02) to: 1) assess the acceptability and willingness of families to participate in a HU trial; 2) develop a safety protocol for using HU in a trial setting in sub-Saharan Africa; and 3) prepare for a definitive phase III Trial. In the Sickle Cell Disease Stroke Prevention in Nigeria (SPIN) trial, our primary hypothesis in the internal feasibility trial is that 80% adherence for daily HU administration is feasible. Procedure: The internal pilot is a single site; single arm trial enrolling 40 children aged 5 to 12 years with hemoglobin SS or SB0 thalassemia at risk of developing stroke with a high transcranial Doppler (TCD) velocity in the middle cerebral artery (MCA) ≥ 200 cm/sec. Each participant is scheduled to receive low dose HU therapy (~20mg/kg/day) for 36 months. Acceptability was determined by the number of families who consented for screening. The adherence rate of HU was based on monthly parental assessment of the Morisky Medical Adherence Sore (MMAS) and monthly complete blood count (CBC) to monitor the serial change in mean corpuscular volume (MCV) from baseline level. Assessment of toxicity attributable to HU was based on comparing adverse events between the HU and control groups. Controls were identified as participants that met the criteria for the trial, but had TCD measurements &lt; 200 cm/sec. From Baby HUG, adverse events were defined as hospitalization for any cause, severe anemia and myelosuppression (severe neutropenia and thrombocytopenia based on monthly CBC). Results: A total of 269 participants were approached, of which 96% (23 of 24) and 86% (211 of 245) with an elevated or normal TCD measurement agreed to enroll in the HU therapy or control groups with a median age of 8 and 7.6 years, respectively. At the current milestone, 100% of the participants enrolled in the treatment arm demonstrated at least average to high monthly adherence rate (MMAS of 6-8 points). This adherence rate was consistent with an increase in MCV from baseline to 3 months after starting HU therapy with a minimum increase in MCV of at least 3 fl in 8 of 11 participants. One child on HU therapy was hospitalized for 5 days for hypovolemia and dehydration associated with cholera. The table below shows no excessive rate of adverse events when HU therapy and control groups are compared. Conclusion: These early results demonstrate the ability for a sub-Saharan African clinical research team to plan and initiate a complex SCD trial. Our preliminary data provide strong evidence for acceptability and potential safety of low dose HU therapy in Nigerian children with SCD. Completion of the internal pilot should provide sufficient evidence to pursue a phase III trial of low dose HU therapy to prevent strokes in children living in sub-Saharan Africa

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

Strokes in children with sickle cell anemia (SCA) are associated with significant morbidity and premature death. Primary stroke prevention in children with SCA involves screening for abnormal transcranial Doppler (TCD) velocity coupled with regular blood transfusion therapy for children with abnormal velocities, for at least one year. However, in Africa, where the majority of children with SCA live, regular blood transfusions are not feasible due to inadequate supply of safe blood, cost, and the reluctance of caregivers to accept transfusion therapy for their children. We describe the Primary Prevention of Stroke in Children with Sickle Cell Disease in Nigeria Trial [StrokePreventioninNigeria (SPRING) trial, NCT02560935], a three-center double-blinded randomized controlled Phase III clinical trial to 1) determine the efficacy of moderate fixed-dose (20 mg/kg/day) versus low fixed-dose (10 mg/kg/day) hydroxyurea therapy for primary stroke prevention; 2) determine the efficacy of moderate fixed-dose hydroxyurea for decreasing the incidence of all cause-hospitalization (pain, acute chest syndrome, infection, other) compared to low fixed-dose hydroxyurea. We will test the primary hypothesis that there will be a 66% relative risk reduction of strokes in children with SCA and abnormal TCD measurements, randomly allocated, for a minimum of three years to receive moderate fixed-dose versus low fixed-dose hydroxyurea (total n = 220). The results of this trial will advance the care of children with SCA in sub-Saharan Africa, while improving research capacity for future studies to prevent strokes in children with SCA.</p