Quantitative, Point-of-Care Immunoassay Platform to Guide and Monitor Sickle Cell Disease Therapy.

Sickle cell patients often require monthly transfusions with normal blood to treat the many complications of the disease. In this therapy, the clinician lowers the amount of hemoglobin S (HbS) containing red blood cells (RBCs) by transfusing normal blood units containing hemoglobin A (HbA). We have developed a point-of-care (POC) quantitative immunoassay for HbS to serve as a diagnostic aid for clinicians providing this life-saving treatment. The test consists of a small-footprint reader and cartridges that quantify the percentage of HbS in a small volume of patient blood. The test reports % HbS values in the range from 5 to 86% that highly correlate (slope 1.03, R(2) = 0.97) with currently used central laboratory HPLC systems. The test also shows a 1% limit of blank, 2% limit of detection, and 5% limit of quantitation. The test was also shown to encounter minimal effects from potential interferences. This cost-effective, POC HbS quantitative approach will allow for real-time transfusion monitoring in sickle cell treatment settings and therefore improve workflow and allow clinicians to quickly make informed therapeutic decisions.

Validation of a novel point of care testing device for sickle cell disease.

BACKGROUND: Sickle cell disease is one of the most common inherited blood disorders. Universal screening and early intervention have significantly helped to reduce childhood mortality in high-resource countries. However, persons living in low-resource settings are often not diagnosed until late childhood when they present with clinical symptoms. In addition, confirmation of disease in affected individuals in the urgent care setting is limited in both high- and low-resource areas, often leading to delay in treatment. All of the current diagnostic methods rely on advanced laboratory systems and are often prohibitively expensive and time-consuming in low-resource settings. To address this need, the Sickle SCAN™ test has been developed to diagnose sickle cell disease and sickle cell trait at the point of care without electricity or advanced equipment. METHODS: This study was conducted to evaluate and validate the diagnostic accuracy of the Sickle SCAN™ test, a novel point of care test for sickle cell disease. Thus, we describe the laboratory testing and clinical validation of the Sickle SCAN™ test in individuals >1 year of age using capillary blood. The Sickle SCAN™ test was created using advanced, qualitative lateral flow technology using capillary blood to identify the presence of hemoglobin A, S, and C allowing for detection of results with the naked eye. RESULTS: Laboratory testing using venous blood demonstrated 99 % sensitivity and 99 % specificity for the diagnosis of HbSS, HbAS, HbSC, HbAC, and HbAA. Seventy-one subjects underwent capillary blood sampling at the point of care for further validation. This test detected the correct A, S, and C presence with an overall diagnostic accuracy of 99 % at the bedside. CONCLUSION: The Sickle SCAN™ test has the potential to significantly impact the diagnosis and treatment for sickle cell disease worldwide as well as enhance genetic counseling at the point of care. Further validation testing will be conducted in newborns in resource-poor settings in upcoming studies.