P-062: MATRIX COMPARISON OF HEMOTYPESC AND SICKLESCAN POINT-OF-CARE DIAGNOSTICS FOR EARLY DIAGNOSIS OF SICKLE CELL DISEASE IN RURAL SUB-SAHARAN AFRICA

Abstract

Purpose: In sub-Saharan Africa, universal sickle cell disease-newborn screening (SCD-NBS) programs are nonexistent due to high costs associated with conventional laboratory technologies, competing for national healthcare priorities, and budgetary constraints. However, the recent emergence of lateral-flow immunoassay microtechnology point-of-care tests (POCT) such the SickleSCAN™ and HemoTypeSC™ present exciting opportunities to change the status quo and potentially revolutionize healthcare for children as best practice for early diagnosis of SCD. Materials and methods: We perform a matrix comparison of diagnostic accuracy in field conditions for the SickleSCAN™ and HemoTypeSC™ tests. We assessed the performance characteristics of SickleSCAN™ and HemoTypeSC™ by evaluating children with positive Emmel test for HbSS, HbSC, and HbAS; and children, including newborns, without known coagulopathy in a rural district in Sierra Leone. Results: A total of seventy-four (33 females/41 males) children from three participating community health centers were analyzed by both methods. The ages ranged from twenty-four hours old to seventeen years old. HemoTypeSC™ and SickleSCAN™ correctly identified hemoglobinopathy phenotypes in 26 children with positive Emmel test as follows: twenty HbSS and four HbAS. Two positive Emmel test results (HbAS) were identified as HbAC and HbAA by the two tests indicating that the two tests have excellent sensitivity and specificity for the identification of the HbS pattern, consistent with SCD. Of the 74 samples that had two SCD POCT scores, there was no discordant result between the HemoTypeSC™ and the SickleSCAN™. Results for both tests were as follows: HbAA 36 (46.8%), HbAS 17 (22.1%), HbSC 1 (1.3%), and HbSS (26.0%). No newborns were identified with sickle cell disease (HbSS). The two tests identified seven newborns with sickle cell trait (HbAS). Twenty-one newborns had the normal HbAA genotype. Overall, HemoTypeSC™ and SickleSCAN™ exhibited sensitivity and specificity of 100% and 100% respectively for all possible phenotypes (HbAA, HbAS, and HbSS) detected. Conclusion: The HemoTypeSC and SickleSCAN tests demonstrated 100% concordance for identifying homozygote healthy people, sickle cell trait, and disease patients in this study. Our matrix comparison study highlighted the potential use of POCTs as both first?tier and second-tier screening and confirmation tests when presumptive SCD or trait is indicated. This is an acceptable practice for SCD screening as the current consensus is to use the same method on the same sample if no second?tier screening method is available and to confirm the screening result with a second method on a second sample to make a diagnosis. We, therefore, conclude that POCTs are suitable for population and newborn screening for the HbS phenotype in limited-resource settings where the disease burden is greatest and conventional laboratory methods are nonexistent. The authors do not declare any conflict of interest