The Role of Hydroxyurea to Prevent Silent Stroke in Sickle Cell Disease: Systematic Review and Meta-Analysis

Chronic blood transfusions are standard of care for stroke prevention in sickle cell disease. We evaluated hydroxyurea's efficacy in preventing silent stroke. We searched for randomized controlled trials (RCTs) and observational studies on Pubmed, CENTRAL, Embase, and Web of Science without using language/time limits. Eligible studies compared hydroxyurea with transfusions or observation to prevent silent stroke. This systematic review adheres to the Cochrane guidelines. Data were pooled using random effects model using STATA to perform meta-analysis. Methodological quality of RCTs was investigated using the Cochrane risk of bias assessment tool, while observational studies were assessed using the Downs & Black Checklist for Study Quality. One RCT enrolling 121 participants was included. There were no strokes, silent strokes, or deaths reported in either arm. There was no difference between hydroxyurea versus chronic blood transfusions (RR 1.52, 95% CI 0.57 to 4.02, P = 0.39) for adverse events. We included 10 observational studies, with 361 participants receiving hydroxyurea. There were no deaths attributed to hydroxyurea. Approximately 1% (I² = 48.67%, 95% CI 0.0 to 0.05, 314 participants, seven comparisons) of patients receiving hydroxyurea had stroke. Approximately 18% (I² = 91.37%, 95% CI 0.03 to 0.4, 266 participants, six comparisons) of the hydroxyurea patients had silent stroke. Approximately 24% (I² = 88.54%, 95% CI 0.02 to 0.57, 91 participants, four comparisons) of the hydroxyurea patients had adverse events attributed to hydroxyurea. Our findings suggest that hydroxyurea is safe and may prevent silent stroke and stroke. More high-quality studies are needed.