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Abstract Background Sickle cell disease (SCD) represents a collection of inherited hematological disorders characterized by abnormal sickle-shaped erythrocytes resulting in an increased risk of morbidity and mortality. SCD represents a significant global health burden, affecting more than 300, 000 newborns per year. Most of these births occur in resource limited areas, including sub-Saharan Africa, where the mortality rate before the age of five is estimated to be as high as 50-80% and the existing infrastructure and resources cannot support most current and robust methods that offer hemoglobin variant detection and quantification for the diagnosis and monitoring of SCD. While newborn screening programs (NBS) to identify individuals affected with SCD have demonstrated efficacy in reducing morbidity and early mortality, NBS programs are limited outside of the US and Europe and face many practical challenges for universal implementation in a resource limited setting. The need for inexpensive and reliable hemoglobin variant detection and quantification at the Point of Care is essential to the diagnosis and management of SCD in resource limited settings with a high prevalence of SCD, and the expansion of NBS programs. This study aims to evaluate an inexpensive testing strategy using two methodologies for POC screening and confirmation of SCD that could be supported in a low resource setting. Methods The two-step testing strategy for evaluation of POC testing for hemoglobin variant detection and quantification included testing residual specimens from normal and known sickle cell patients by first screening with the HemoTypeSC, a qualitative lateral flow immunoassay (LFIA) that has improved sensitivity and specificity from other available LFIA methodologies given the use of monoclonal antibodies for the detection of hemoglobin variants. Confirmatory testing and quantification of hemoglobin variants was accomplished with the use of the Gazelle POC test a miniaturized chip-based cellulose acetate electrophoresis device capable of identification and quantification of normal and variant hemoglobin. Statistical evaluation of device performance and clinical agreement between the device and known disease status was achieved in EP evaluator. Results The two-tier testing strategy demonstrated effective and inexpensive mechanism for SCD screening and confirmation. Overall, the HemoTypeSC and Gazelle demonstrated 100% qualitative agreement between methods, with the total cost of the two-tiered testing strategy estimated at under 6 per sample. Conclusions In conclusion, the two-tiered approach using the HemoTypeSC and Gazelle yielded a practical and cost-effective strategy for screening and confirmation of hemoglobin variants for the detection and monitoring of SCD. Both the strip and chip-based methodologies provide rapid results, are accessible at the point-of-care, and require minimal sample volume, a feature ideal for use in a pediatric population in low resource settings. Overall, these methods show promise for the use and expansion of NBS programs to improve public health initiatives for the diagnosis of SCD.
Schuler et al. (Tue,) studied this question.