High hydroxyurea usage in sickle cell anemia regardless of patient demographics.

Hydroxyurea is highly effective in sickle cell disease, but it is still underutilized. Reports of hydroxyurea utilization largely use Medicaid data, and socioeconomics is often cited as a barrier. To address whether patient demographics influenced the high hydroxyurea usage rate recently reported for the pediatric sickle cell program of Northern Virginia, analysis of data from 2011 to 2021 revealed no statistical difference in hydroxyurea usage rate between Medicaid and non-Medicaid, African American and African, or age less than 13 and age greater than or equal to 13 years cohorts, demonstrating that hydroxyurea can be successfully implemented across demographic groups.

Effect of voxelotor on cardiopulmonary testing in youths with sickle cell anemia in a pilot study.

BACKGROUND: Individuals with sickle cell anemia (SCA) exhibit decreased exercise capacity. Anemia limits oxygen-carrying capacity and affects cardiopulmonary fitness. The drug voxelotor raises hemoglobin in SCA. We hypothesized that voxelotor improves exercise capacity in youths with SCA. METHODS: In a single-center, open-label, single-arm, longitudinal interventional pilot study (NCT04581356), SCA patients aged 12 and older, stably maintained on hydroxyurea, were treated with 1500 mg voxelotor daily, and performed cardiopulmonary exercise testing before (CPET#1) and after voxelotor (CPET#2). A modified Bruce Protocol was performed on a motorized treadmill, and breath-by-breath gas exchange data were collected. Peak oxygen consumption (peak VO2 ), anaerobic threshold, O2 pulse, VE/VCO2 slope, and time exercised were compared for each participant. The primary endpoint was change in peak VO2 . Hematologic parameters were measured before each CPET. Patient Global Impression of Change (PGIC) and Clinician Global Impression of Change (CGIC) surveys were collected. RESULTS: Ten hemoglobin SS patients aged 12-24 completed the study. All demonstrated expected hemoglobin rise, with average +1.6 g/dL (p = .003) and P50 left shift of average -11 mmHg (p < .0001) with decreased oxygen off-loading at low pO2 . The change in % predicted peak VO2 from CPET#1 to CPET#2 ranged from -12.8% to +11.3%, with significant improvement of more than 5% in one subject, more than 5% decrease in five subjects, and insignificant change of less than 5% in four subjects. All 10 CGIC and seven of 10 PGIC responses were positive. CONCLUSION: In a plot study of 10 youths with SCA, voxelotor treatment did not improve peak VO2 in 9 out of 10 patients.

Ten-year longitudinal analysis of hydroxyurea implementation in a pediatric sickle cell program.

Hydroxyurea (HU) has proven benefit in sickle cell anemia (SCA), but HU is still underutilized. The Pediatric Sickle Cell Program of Northern Virginia prescribes HU regardless of symptoms to all SCA patients age ≥ 9 months and prospectively tracks outcomes. HU is dosed to maximum tolerated dosing (MTD), targeting 30% Hgb F. Longitudinal data from 2009 to 2019 encompassing 1222 HU-eligible and 950 HU-exposure patient-years were analyzed in 2-year intervals for hemoglobin (Hgb), fetal hemoglobin (Hgb F), hospitalizations, transfusions, and treat-and-release ED visits. Comparing HU-eligible patients in the interval prior to HU implementation (2009-2011) to the last interval analyzed after HU implementation (2017-2019), HU usage increased from 33% to 93%, average Hgb increased from 8.3 ± 0.98 to 9.8 ± 1.3 g/dl (p < .0001), average Hgb F rose from 13 ± 8.7% to 26 ± 9.9% (p < .0001), hospitalizations decreased from 0.71 (95% CI 0.54-0.91) to 0.2 (95% CI 0.13-0.28) admissions/person-year, sporadic transfusions decreased from 0.4 (95% CI 0.27-0.55) to 0.05 (95% CI 0.02-0.12) transfusions/person-year. Treat-and-release ED visit rates remained unchanged, varying between 0.49 (95% CI 0.36-0.64) and 0.64 (95% CI 0.48-0.83) visits/person-year. By the last interval, 72% of patients had Hgb ≥ 9 g/dl, 42% had Hgb F ≥ 30%, 79% experienced no hospitalizations, and 94% received no transfusions. Uniform HU prescription for SCA patients with close monitoring to achieve high Hgb F resulted in significant improvements in laboratory and clinical outcomes within 2 years, which continued to improve over the next 6 years. Rigorous HU implementation in a pediatric sickle cell population is feasible, effective, and sustainable.