Hydroxyurea Dose Escalation for Sickle Cell Anemia in Sub-Saharan Africa.

BACKGROUND: Hydroxyurea has proven safety, feasibility, and efficacy in children with sickle cell anemia in sub-Saharan Africa, with studies showing a reduced incidence of vaso-occlusive events and reduced mortality. Dosing standards remain undetermined, however, and whether escalation to the maximum tolerated dose confers clinical benefits that outweigh treatment-related toxic effects is unknown. METHODS: In a randomized, double-blind trial, we compared hydroxyurea at a fixed dose (approximately 20 mg per kilogram of body weight per day) with dose escalation (approximately 30 mg per kilogram per day). The primary outcome was a hemoglobin level of 9.0 g or more per deciliter or a fetal hemoglobin level of 20% or more after 24 months. Secondary outcomes included the incidences of malaria, vaso-occlusive crises, and serious adverse events. RESULTS: Children received hydroxyurea at a fixed dose (94 children; mean [±SD] age, 4.6±1.0 years) or with dose escalation (93 children; mean age, 4.8±0.9 years); the mean doses were 19.2±1.8 mg per kilogram per day and 29.5±3.6 mg per kilogram per day, respectively. The data and safety monitoring board halted the trial when the numbers of clinical events were significantly lower among children receiving escalated dosing than among those receiving a fixed dose. At trial closure, 86% of the children in the dose-escalation group had reached the primary-outcome thresholds, as compared with 37% of the children in the fixed-dose group (P<0.001). Children in the dose-escalation group had fewer sickle cell-related adverse events (incidence rate ratio, 0.43; 95% confidence interval [CI], 0.34 to 0.54), vaso-occlusive pain crises (incidence rate ratio, 0.43; 95% CI, 0.34 to 0.56), cases of acute chest syndrome or pneumonia (incidence rate ratio, 0.27; 95% CI, 0.11 to 0.56), transfusions (incidence rate ratio, 0.30; 95% CI, 0.20 to 0.43), and hospitalizations (incidence rate ratio, 0.21; 95% CI, 0.13 to 0.34). Laboratory-confirmed dose-limiting toxic effects were similar in the two groups, and there were no cases of severe neutropenia or thrombocytopenia. CONCLUSIONS: Among children with sickle cell anemia in sub-Saharan Africa, hydroxyurea with dose escalation had superior clinical efficacy to that of fixed-dose hydroxyurea, with equivalent safety. (Funded by the Doris Duke Charitable Foundation and the Cincinnati Children's Research Foundation; NOHARM MTD ClinicalTrials.gov number, NCT03128515.).

Hydroxyurea Therapy for Neurological and Cognitive Protection in Pediatric Sickle Cell Anemia in Uganda (BRAIN SAFE II): Protocol for a single-arm open label trial.

Background: Children with sickle cell anemia (SCA) in Sub-Saharan Africa are at high risk of sickle cerebrovascular injury (SCVI). Hydroxyurea, a commonly used disease-modifying therapy, may prevent or decrease SCVI for reduced incident stroke, stroke risk and potentially cognitive dysfunction. We aim to test the impact of daily hydroxyurea therapy on these outcomes in Ugandan children with SCA. We hypothesize that hydroxyurea therapy over 36 months will prevent, stabilize or improve these complications of SCA. Methods: The BRAIN SAFE II study is an open-label, single-arm trial of daily hydroxyurea for 270 children with SCA (HbSS) in Uganda, ages 3-9 years. Following baseline assessments, participants began hydroxyurea therapy and clinically followed per local guidelines. Standard hydroxyurea dose is escalated to maximum tolerated dose (MTD). SCVI is assessed by cerebral arterial velocity using Doppler ultrasound, with cognitive function determined by formal neurocognitive testing (primary outcomes). Structural SCVI is assessed by magnetic resonance imaging (MRI) and angiography (MRA) in a sub-sample of 90 participants ages ≥5 years, along with biomarkers of anemia, inflammation and malnutrition (secondary outcomes). At trial midpoint (18 months) and completion (36 months), primary outcomes will be compared to participants' baseline to determine hydroxyurea impact and relationships to secondary outcomes. Conclusion: This open-label, single-arm trial will examine the impact of hydroxyurea on preventing or ameliorating SCA SCVI in children, assessed by reducing incident stroke, stroke risk and neurocognitive dysfunction. Trial results will provide important insight into the role of hydroxyurea therapy on critical manifestations of SCVI in children with SCA.

Cost-Effectiveness of Hydroxyurea for Sickle Cell Anemia in a Low-Income African Setting: A Model-Based Evaluation of Two Dosing Regimens.

BACKGROUND AND OBJECTIVE: The disease burden of sickle cell anemia (SCA) in sub-Saharan African (SSA) countries is substantial, with many children dying without an established diagnosis or proper treatment. The global burden of SCA is increasing each year, making therapeutic intervention a high priority. Hydroxyurea is the only disease-modifying therapy with proven feasibility and efficacy suitable for SSA; however, no one has quantified the health economic implications of its use. Therefore, from the perspective of the health care provider, we estimated the incremental cost-effectiveness of hydroxyurea as a fixed-dose regimen or maximum tolerated dose (MTD) regimen, versus SCA care without hydroxyurea. METHODS: We estimated the cost of providing outpatient treatment at a pediatric sickle cell clinic in Kampala, Uganda. These estimates were used in a discrete-event simulation model to project mean costs (2021 US$), disability-adjusted life years (DALYs), and consumption of blood products per patient (450 mL units), for patients between 9 months and 18 years of age. We calculated cost-effectiveness as the ratio of incremental costs over incremental DALYs averted, discounted at 3% annually. To test the robustness of our findings, and the impact of uncertainty, we conducted probabilistic and one-way sensitivity analyses, scenario analysis, and price threshold analyses. RESULTS: Hydroxyurea treatment averted an expected 1.37 DALYs and saved US$ 191 per patient if administered at the MTD, compared with SCA care without hydroxyurea. In comparison, hydroxyurea at a fixed dose averted 0.80 DALYs per patient at an incremental cost of US$ 2. The MTD strategy saved 11.2 (95% CI 11.1-11.4) units of blood per patient, compared with 9.1 (95% CI 9.0-9.2) units of blood per patient at the fixed-dose alternative. CONCLUSIONS: Hydroxyurea at MTD is likely to improve quality of life and reduce the consumption of blood products for children with SCA living in Uganda. Compared with a fixed dose regimen, treatment dosing at MTD is likely to be a cost-effective treatment for SCA, using realistic ranges of hydroxyurea costs that are relevant across SSA. Compared with no use of the drug, hydroxyurea could lead to substantial net savings per patient, while reducing the disease morbidity and mortality and increasing quality of life.

Orbital compression syndrome in a Ugandan child with sickle cell disease: A case report.

Orbital compression syndrome is a rare acute complication of sickle cell disease that may impair vision. Assessment by a multidisciplinary team incorporates detailed history and physical examination, fundoscopy, and appropriate imaging to exclude infections or neoplasms. Supportive treatment is adequate unless there is evidence of life-threatening space-occupying lesion warranting surgery.