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Performance testing of quantitative G6PD Point-of-Care test in Thailand

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Background: Treatment with 8-aminoquinoline drugs, such as primaquine and tafenoquine (in development), used for radical cure treatment of Plasmodium vivax, can cause serious side-effects in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Testing of G6PD enzyme activity is thus needed prior to safely administering primaquine. Materials and Methods: We are developing an assay system that determines hemoglobin (Hb) concentration and G6PD enzyme activity, normalized to hemoglobin, from a single 10 µl fingerstick or venous blood sample. The assay format consists of a simple, easy-to-use assay and portable reader that will enable testing and treatment at the Point-of-Care (POC). Our assay system utilizes an optical system to measure Hb as well as NADPH production in order to quantitatively determine Hb concentration and G6PD enzyme activity. Results are displayed 5 min after inserting a sample into the portable, battery-powered, reader. The reader is functional over a broad temperature range (18 – 40 °C) and utilizes an on-board algorithm for temperature correction. Results and Conclusions: Assay performance was independently tested at BD Technologies, PATH and in a recently completed 150 patient field study at the Shoklo Malaria Research Unit in Mae Sot, Thailand. Samples were tested with the BD assay system as well as gold standard tests, the Trinity Biotech Quantitative G6PD assay kit for G6PD enzyme activity and either the Hemocue System or a Complete Blood Count (CBC) for Hb concentration. The results indicate good correlation between the BD assay system and the gold standard tests for both G6PD enzyme activity and Hb concentration.