Characteristics of a rapid, point‐of‐care lateral flow immunoassay for the diagnosis of sickle cell disease

Abstract

Sickle cell disease (SCD) is a common and life-threatening hematological disorder, affecting approximately 400,000 newborns annually worldwide. Most SCD births occur in low-resource countries, particularly in subSaharan Africa, where limited access to accurate diagnostics results in early mortality. We evaluated a prototype immunoassay as a novel, rapid, and low-cost point-of-care (POC) diagnostic device (Sickle SCAN TM ) designed to identify HbA, HbS, and HbC. A total of 139 blood samples were scored by three masked observers and compared to results using capillary zone electrophoresis. The sensitivity (98.3-100%) and specificity (92.5-100%) to detect the presence of HbA, HbS, and HbS were excellent. The test demonstrated 98.4% sensitivity and 98.6% specificity for the diagnosis of HbSS disease and 100% sensitivity and specificity for the diagnosis of HbSC disease. Most variant hemoglobins, including samples with high concentrations of HbF, did not interfere with the ability to detect HbS or HbC. Additionally, HbS and HbC were accurately detected at concentrations as low as 1-2%. Dried blood spot samples yielded clear positive bands, without loss of sensitivity or specificity, and devices stored at 378C gave reliable results. These analyses indicate that the Sickle SCAN POC device is simple, rapid, and robust with high sensitivity and specificity for the detection of HbA, HbS, and HbC. The ability to obtain rapid and accurate results with both liquid blood and dried blood spots, including those with newborn high-HbF phenotypes, suggests that this POC device is suitable for large-scale screening and potentially for accurate diagnosis of SCD in limited resource settings.

Sickle cell anemia in sub-Saharan Africa: advancing the clinical paradigm through partnerships and research

“…The NHLBI Small Business Innovation Research grant program 24 has stimulated development of POC diagnostics for SCA, and several devices have encouraging preliminary results. [25][26][27][28][29] Beyond reported successes and accuracy in controlled laboratory settings, these preliminary findings must be validated in "real world" African settings, to confirm that the devices produce reliable results in the hands of those who will use them. Such efforts are ongoing through partnered research, and we predict that within 3 years, several accurate POC devices will be validated and ready for widespread use across sub-Saharan Africa.…”

A rapid, inexpensive and disposable point‐of‐care blood test for sickle cell disease using novel, highly specific monoclonal antibodies

“…While these represent significant advances in diagnostic capabilities for SCD, each has deficiencies. Each method requires an instrument as either an integral part of the procedure or to achieve maximum sensitivity and specificity (Piety et al , 2016; McGann et al , 2016), which can be prohibitive in low-resource settings. In addition, none of these methods achieve 100% accuracy with or without instrumentation.…”

A Paper-Based Test for Screening Newborns for Sickle Cell Disease

“…Various modifications of conventional laboratory methods (e.g., lower-cost implementation of IEF20, or a microfluidics-based HE21) as well as novel diagnostic approaches (e.g., density-based separation of sickle RBCs in capillaries2223, or magnetic levitation-based smartphone platforms24) may reduce the cost of testing and/or may be performed at the point-of-care but continue to require highly trained personnel and rely on complex specialized equipment and electricity to operate. Rapid diagnostic tests for SCD based on conventional lateral flow immunoassay technology are instrument- and electricity-free and show great potential252627. However, these tests still require extensive field-testing to determine real-world performance for newborn samples and for tests performed in resource-limited settings, and are subject to well-known limitations of all antibody-based assays, such as limited shelf-lives when ambient temperatures exceed recommended ranges for even short periods of time during shipping, storage or usage – a scenario which is highly likely in resource-limited setting such as sub-Saharan Africa28.…”