Sickle Cell Disease (SCD), an inherited hemoglobinopathy, disproportionately affects people from the African subcontinent extensively. The World Health Organization estimates that sub-Saharan Africa (SSA) shoulders around 75% of the disease's global burden, with the mortality rate of children under five years of age reaching up to 90% and an estimated 80% of the affected children remain undiagnosed 1-3. Nigeria has the highest burden of sickle cell disease (SCD) in the world, with an estimated 150,000 babies born with SCD each year and approximately 2–3% of the population affected Early diagnosis and timely intervention have proven to be effective in mitigating the disease's deadly manifestations 4,5. Current gold standard tests for these diseases include high performance liquid chromatography (HPLC), electrophoresis, and complete blood count. which necessitate advanced laboratory infrastructure and are associated with considerable costs and prolonged turnaround times, potentially leading to delays in providing feedback to patients. Consequently, there remains a gap in reliable data on the true prevalence rates of SCD and SCD trait 6.

Here, we present the results of a large-scale clinical study for SCD screening among Nigerian children. Testing for SCD was performed using Gazelle, a novel paper-based microchip point-of-care platform designed to test for hemoglobinopathies7. The current Gazelle system is packaged as a battery-powered, rugged, affordable device with embedded GPS, Wi-Fi, and Bluetooth and is designed for use in clinics as well as remote settings. The reader allows for digital data entry and can store up to 1000 test results. An on-board interface software application performs quality checks, automatically interprets and objectively displays the test results to the user and allows the user to print the test results wirelessly, store them in PDF format, or securely transmit the results directly to the information cloud.

Institutional review board approval was obtained and blood samples from a total of 1360 subjects with unknown hemoglobinopathy status were collected from selected tertiary hospitals in Kano city. Gazelle testing done at The International Foundation Against Infectious disease in Nigeria (IFAIN) satellite lab in Kano, while HPLC testing was done at IFAIN central lab in Abuja. The study included 162 neonates (0 – 30 days), 145 newborns (2 – 6 months), 689 infants (6 months – 2years), 349 children (2 – 12 years), 5 adolescents (12 – 22 years), and 10 adults (22 years and older). Additionally, 733 (53.9%) of the subjects were males and 627 (46.1%) were females. Tests were performed by local users, including healthcare workers and clinical laboratory personnel, who underwent a short training on the use of the Gazelle platform. Moreover, reference test results were not available to Gazelle platform users, and Gazelle results were not accessible to those performing the HPLC tests.

Statistical analyses show sensitivity values of 100% for disease vs. normal and disease vs. trait, and 99.7% for trait vs. normal. Specificity was 100% for disease vs. normal and disease vs. trait, and 94.2% for Trait vs. normal. Prevalence rates showed superior agreement with those calculated from the HPLC tests; both Gazelle and HPLC showed a prevalence rate of SCD of 0.58%. While Gazelle reports SCD trait prevalence rate of 23.08% which is in close agreement with the HPLC rate at 21.83%.

In conclusion, this study supports the integration of novel diagnostic platform Gazelle into national screening strategies, particularly in regions with high SCD burden and limited access to conventional diagnostics. The platform's ease of use, portability, and robust performance can help overcome key barriers in hemoglobinopathy screening and expand access to timely, life-saving care.

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