The impact of Hydroxyurea on the rates of Vaso–occlusive crises in patients with sickle cell disease in Saudi Arabia: a single–center study

BACKGROUND: Vaso–occlusive crises (VOCs) are acute and common painful complication of sickle cell disease (SCD), and are the main reason behind the frequent emergency department visits among SCD patients. Hydroxyurea (HU) is an old and commonly used medication that demonstrated its effectiveness in reducing the risk of VOCs and the incidence of hospitalization. Although multiple studies have examined the impact of HU on the rates of VOCs, few have explored its effectiveness among SCD patients in Saudi Arabia. METHODS: This was a single–center retrospective cohort study in which the electronic medical records of patients with SCD who have not had any previous exposure to HU prior to the initiation of HU treatment for ≥12 months were recruited. Paired t–test was conducted to examine the difference in the rates of VOCs, and levels of hemoglobin (Hgb), hematocrit (HCT), and platelet counts (PLT Ct) prior to the initiation of HU therapy and 12 months later. Multiple linear regression was conducted to examine whether age, gender, use of opioid analgesics, Hgb, HCT, and PLT Ct levels predict higher or lower rates of VOCs. RESULTS: One hundred and fifty–six patients met the inclusion criteria and were included in the analysis. About 51% of the patients were males, and their mean age was 12.69 years. The mean HU dosage was 16.52 mg/kg/day, and the mean reduction in the rate of VOCs was 1.36 events per patient per year (95% CI [1.03–1.70], p < 0.0001) after the initiation of HU. Females were more likely to have greater reduction in the rates of VOCs in comparison to their male counterparts (β–estimate = 12.85, 95% CI [0.759–24.93], p = 0.0374). CONCLUSION: The use of HU results in a significant reduction in the rates of VOCs and emergency department visits. Future studies with robust research designs should be conducted to further examine the impact of HU on VOCs, hospitalization, and length of stay as well as compare HU to other newly approved medications for SCD, such as crizanlizumab.