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

Abstract

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.

Keywords: United States; red blood cell alloimmunisation; sickle cell disease; transfusion.