Diagnostic accuracy in field conditions of the sickle SCAN® rapid test for sickle cell disease among children and adults in two West African settings: the DREPATEST study

Abstract

BackgroundSickle cell disease (SCD) accounts for 5% of mortality in African children aged < 5 years. Improving the care management and quality of life of patients with SCD requires a reliable diagnosis in resource-limited settings. We assessed the diagnostic accuracy of the rapid Sickle SCAN® point-of-care (POC) test for SCD used in field conditions in two West-African countries.MethodsWe conducted a case-control study in Bamako (Mali) and Lomé (Togo). Known cases of sickle cell disease (HbSS, HbSC), trait (HbAS), HbC heterozygotes (HbAC) and homozygous (HbCC), aged ≥6 months were compared to Controls (HbAA), recruited by convenience. All subjects received both an index rapid POC test and a gold standard (high-performance liquid chromatography in Bamako; capillary electrophoresis in Lomé). Personnel conducting tests were blinded from subjects’ SCD status. Sensitivity and specificity were calculated for each phenotype. Practicality was assessed by local healthcare professionals familiar with national diagnostic methods and their associated constraints.ResultsIn Togo, 209 Cases (45 HbAS, 39 HbAC, 41 HbSS, 44 HbSC and 40 HbCC phenotypes) were compared to 86 Controls (HbAA). 100% sensitivity and specificity were observed for AA Controls and HbCC cases. Estimated sensitivity was 97.7% [95% confidence interval: 88.0–99.9], 97.6% [87.1–99.9%], 95.6% [84.8–99.5%], and 94.9% [82.7–99.4], for HbSC, HbSS, HbAS, and HbAC, respectively. Specificity exceeded 99.2% for all phenotypes. Among 160 cases and 80 controls in Mali, rapid testing was 100% sensitive and specific. Rapid testing was well accepted by local healthcare professionals.ConclusionRapid POC testing is 100% accurate for homozygote healthy people and excellent (Togo) or perfect (Mali) for sickle cell trait and disease patients. In addition to its comparable diagnostic performance, this test is cheaper, easier to implement, and logistically more convenient than the current standard diagnostic methods in use. Its predictive value indicators and diagnostic accuracy in newborns should be further evaluated prior to implementation in large-scale screening programs in resource-limited settings where SCD is prevalent.

Evaluation of a point‐of‐care method for screening blood donors for sickle cell status

“…The findings of this pilot project suggest that POC testing could be a reasonable option for screening donors for the presence of HbS at presentation for initial evaluation. Available evidence has proven it to be an accurate POC test for SCD, with test failure only rarely reported in extreme weather conditions or high humidity . It requires minimal training and can be performed at the time of hemoglobin measurement for donor qualification.…”

“…Available evidence has proven it to be an accurate POC test for SCD, 18,20,23 with test failure only rarely reported in extreme weather conditions or high humidity. 24 It requires minimal training and can be performed at the time of hemoglobin measurement for donor qualification.…”

The Profile of Glycated Hemoglobin in Non-Diabetic Pregnant Women with Preeclampsia: A Case-Control Study in Kinshasa, the Democratic Republic of Congo

“…The fasting blood glycaemia test was carried out using the Cobas C111 analyzer. SICKLE SCAN [37] was applied to find sickle cell anemia among these women. Obstetric ultrasound and fetal monitoring (NST) were used to establish the fetal well-being score (Manning score) and to search for fetal complications such as fetal growth retardation, fetal distress and death in utero.…”

Access to emergency departments for acute events and identification of sickle cell disease in refugees

“…The aim was to fast-track the care of individuals with SCD and the collection of relevant demographic data. [3][4][5] The results were validated by high-performance liquid chromatography, the standard gold-standard screening method. [3][4][5] Based on data from the Italian Ministry of the Interior, a total of 624 688 refugees landed on the Italian coast between 2014 and 2017 ( Figure 1A).…”

“…[3][4][5] The results were validated by high-performance liquid chromatography, the standard gold-standard screening method. [3][4][5] Based on data from the Italian Ministry of the Interior, a total of 624 688 refugees landed on the Italian coast between 2014 and 2017 ( Figure 1A). 6 Refugees from Syria represented only 4% to 25% of these each year ( Figure 1A-B), whereas 21% to 53% came from sub-Saharan African countries (21% in 2014, 31% in 2015, 53% in 2016, and 46% in 2017).…”