Background/Case Studies: Sickle cell is a high prevalence disease in Costa Rica and worldwide. These patients suffer from chronic hemolytic anemia and constant complications which result in the need for blood transfusions. It is recommended, in the most severe cases, to choose erythrocytapheresis rather than simple transfusion to reduce the risk of iron overload and to maintain hemoglobin S levels below 30%, therefore reducing further complications. To achieve this goal, the main transfusion guidelines recommend using RBC with hemoglobin AA genotype; since people with the sickle cell trait have between 35-45% of hemoglobin S, which in certain conditions due to deoxygenation can cause red blood cells to become sickled. Furthermore, RBC units from sickle trait donors failed to achieve a complete leukoreduction. In Costa Rica, there are no screening tests/reagents available for hemoglobin S in RBC units, so this is the first study of sickle cell trait prevalence in Costa Rica donor population. The study was conducted in a pediatric hospital located in the capital city of the country. This is a 330-bed hospital which includes hematology-oncology patients and a sickle cell treatment center. The hospital’s blood supply comes from both the hospital and a blood donor center.
Study
Design/Methods: The hemoglobin S screening was performed on all RBC units collected at both sites. Since there are no hemoglobin S rapid test available in Costa Rica, the test used was capillary electrophoresis with a high sensitivity and specificity to detect hemoglobin variants and allow for the quantitative amount of hemoglobin S. The results from May to October of 2019 were analyzed by SPSS to obtain the absolute frequencies and relative percentage of each electrophoretic pattern. In addition, the range and the average of the percentages of hemoglobin S observed in the units with the hemoglobin AS pattern were calculated.
Results/Findings: Of the 1232 units analyzed, 1217 had the AA electrophoretic pattern, which is considered normal in healthy adults, 11 units had the AS pattern, which corresponds to 0.89% of the total units analyzed. This means that approximately 1 out of 112 units are positive for hemoglobin S heterozygous trait. We also found that these 11 units of the AS genotype had an average of 38.2% hemoglobin S, with a range between 32.8% and 40.3%. Conclusions: The prevalence of sickle cell trait among the donor population in Costa Rica was similar to the one found in the United States according to previous studies, therefore, it will be wise to continue screening the RBC units dedicated to the sickle cell patients in this center and to extend this practice to the other hospitals in the country, although it will be necessary to obtain a less expensive and easier screening test for hemoglobin S.
Importance of research: This is the first report of sickle trait prevalence in donor population in Costa Rica. This study provide valuable information in order to improve the transfusional therapy for the sickle cell patients in our hospital and hopefully inspire other hospitals in the country to start screening RBC units for Hemoglobin S as well.
