Background and Objectives: Hydroxyurea (HU) is the standard treatment for severely affected children with sickle cell disease (SCD). Starting dose is 15-20 mg/kg/day that can be escalated up to 35 mg/kg/day. Ethnic neutropenia is common in this area of the world that requires judicious usage of myelosuppressive drugs. Aim was to assess the efficacy of a lower initial dose of HU and cautious dose escalation regimen in patients with SCD. Methods: We assessed 161 patients with SCD on HU, at Sultan Qaboos University Hospital (SQUH), Muscat, Oman, retrospectively from 1998 to 2008 and prospectively from 2009 to 2011. Starting dose of HU was 10-12 mg/kg/day, adjusted based on response or side effects. Patients were divided into two groups according to the dose of HU (10-15.9 mg/kg/day and 16-26 mg/kg/day). Results: Nineteen patients were excluded for various reasons. Forty-four children were in the low-dose group and 98 were in the high-dose group. There was significant reduction in the annual number of admissions due to vaso-occlusive crisis in both groups (P < 0.001). However, the difference between the two groups was statistically insignificant (P > 0.05). In addition, there was an observed clinical improvement regarding the acute chest syndrome (ACS). Both groups had comparable significant improvements in their laboratory markers [e.g., hemoglobin (Hb), Mean Corpuscular Volume (MCV), and absolute neutrophil count (ANC)]. All 142 patients tolerated the treatment well. Reversible toxicities occurred in both low- and high-dose groups. Conclusion: In SCD patients, low-dose regimen of HU is a feasible option that ensured safety and yet did not affect efficacy.
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