An assessment of the effectiveness of hydroxyurea therapy in children and adolescents with sickle cell anaemia at Kenyatta National Hospital

Abstract

Sickle cell anaemia (SCA) is a major public health concern in Kenya, particularly affecting children and adolescents. Despite the inclusion of hydroxyurea in national treatment guidelines, its real-world use and effectiveness in Kenya remain under-documented, especially in tertiary care settings such as Kenyatta National Hospital (KNH). The drug is known to reduce vaso-occlusive crises (VOCs), transfusions, and hospitalizations, but its impact in resource-limited environments requires further investigation. Hence, this study aimed to assess the clinical and hematological effectiveness of hydroxyurea therapy in children and adolescents with sickle cell anaemia at Kenyatta National Hospital. A retrospective one-arm cohort design was used to review medical records of pediatric patients with sickle cell anaemia (≤ 16 years) who were treated with hydroxyurea at Kenyatta National Hospital between January 2020 and December 2023. Eligible patients had received hydroxyurea therapy for a minimum duration of six months and had at least 12 months of documented follow-up data. Clinical outcomes, including the frequency of vaso-occlusive crises, hospitalizations, acute chest syndrome, stroke events, and transfusion requirements, were assessed alongside hematological markers such as hemoglobin level, mean corpuscular volume, and reticulocyte count. Data were collected using a structured data abstraction tool adapted from previously published studies. Statistical analysis was conducted using IBM SPSS Statistics version 29, with one-way analysis of variance used to examine changes in clinical and hematological parameters across multiple follow-up time points. A total of 54 children and adolescents with sickle cell anaemia (mean age: 6.8 ± 4.4 years) were included, all of whom had a substantial burden of disease at baseline, marked by frequent vaso-occlusive crises (2.6 ± 1.9), hospital admissions (2.4 ± 2.0), blood transfusions (2.9 ± 1.7), and episodes of acute chest syndrome (1.3 ± 0.9). Over the 3, 6, 12, and 24-month follow-up period after initiation of hydroxyurea therapy, overall clinical outcomes showed a general decline in the proportion of patients experiencing vaso-occlusive crises, hospitalizations, transfusion needs, and infections compared with baseline. Hematological parameters demonstrated progressive improvement, with mean hemoglobin rising from 7.8 ± 1.1 g/dL at baseline to 10.5 ± 2.0 g/dL at 24 months, mean corpuscular volume increasing from 77.0 ± 21.1 fL to 96.7 ± 13.2 fL, and reticulocyte counts decreasing from 16.3 ± 11.9% to 6.0 ± 6.9%. Hydroxyurea therapy was associated with sustained improvements in hematological indices, characterized by increased hemoglobin levels and mean corpuscular volume, alongside a reduction in reticulocyte counts over the follow-up period. These changes were accompanied by reductions in key clinical complications, including vaso-occlusive crises and hospitalizations.