Alloimmunisation rates of sickle cell disease patients in the United States differ from those in other geographical regions

SUMMARY Objectives Comparison of the alloimmunisation rates of patients with sickle cell disease in the Unites States versus other countries. Background Sickle cell disease ( SCD ) patients treated with chronic transfusion therapy are at a high risk of red blood cell ( RBC ) alloimmunisation. Materials and Methods We reviewed published literature describing alloimmunisation rates of SCD patients. Average alloimmunisation rates and number of alloantibodies per transfused patient in the United States and other countries were evaluated. Results Twenty‐four studies on alloimmunisation of SCD patients were found, 15 studies with 3,708 patients in the US and 9 studies with 2203 patients from other regions, including South America, the Caribbean, Middle East, Africa and Europe. The United States has a higher alloimmunisation rate (22·33 ± 0·13% versus 16·25 ± 0·35%, p < 0·0001) and a higher number of alloantibodies per transfused patient (0·45 ± 0·003 versus 0·20 ± 0·005, p < 0·0001) than other countries. Brazil with a higher proportion of multi‐ethnic donors demonstrated a lower alloimmunisation rate compared to the United States (14·60 ± 0·40% versus 22·33 ± 0·13%, p < 0·0001) and fewer alloantibodies per transfused patient (0·20 ± 0·02 versus 0·45 ± 0·003, p < 0·0001) than the United States . Conclusion SCD patients in the United States had a higher alloimmunisation rate, which could be reduced by a more ethnically diverse donor pool and a more conservative transfusion strategy in non‐critical conditions.