International Multi-Site Clinical Validation of Point-of-Care Microchip Electrophoresis Test for Hemoglobin Variant Identification

Abstract

Introduction: Nearly 24% of the world's population carry hemoglobin (Hb) gene variants, with the large majority of affected births occurring in low-income countries. The most prevalent structural Hb variants are the recessive β-globin gene mutations, βS or S, βC or C, and βE or E1. Hb S mutation is prevalent in sub-Saharan Africa and in Central India. Hb C is common in West Africa, and Hb E is common in Southeast Asia and in India. Homozygotes or compound heterozygotes with βS (e.g., Hb SS or SC) have sickle cell disease (SCD), a chronic sickling disorder associated with pain, chronic multi-organ damage, and high mortality. While Hb EE causes only a mild microcytic anemia, Hb E in combination with β-thalassemia can lead to transfusion dependent thalassemia. Though carriers are typically asymptomatic, they may pass the mutations to their offspring. Screening is needed so that these disorders can be diagnosed early and managed in a timely manner2. For example, in low-income countries, due to lack of nationwide screening and comprehensive care programs, up to 80% of babies born with SCD are undiagnosed and less than half of them survive beyond 5 years of age2. The unmet need for affordable, portable, accurate point-of-care tests to facilitate decentralized hemoglobin testing in resource-constrained countries is well-recognized 2,3. Here, we present international multi-site clinical validation results and high diagnostic accuracy of the 'HemeChip' (Fig. 1), an affordable, 10-minute point-of-care microchip electrophoresis test for identifying common Hb variants S, C, and E. Methods: Institutional Review Board approvals were obtained at each study site, and blood samples were collected as part of the standard clinical care. Tests were performed by local users, including healthcare workers and clinical laboratory personnel. 315 children (6 weeks to 5 years of age) were tested in Kano, Nigeria. Study participants were enrolled at three hospitals, Amino Kano Teaching Hospital, Murtala Mohammed Specialist Hospital, and Hasiya Bayero Pediatric Hospital. 124 subjects (7 weeks to 63 years old) were included in the study at Siriraj Thalassemia Center in Bangkok, Thailand. 298 subjects (8 months to 65 years old) were tested at a referral testing facility of ICMR-National Institute of Research in Tribal Health, located at Late Baliram Kashayap Memorial Medical College, Jagdalpur, Chhattisgarh, India. Blood samples were tested with both HemeChip and the standard reference methods, high performance liquid chromatography or cellulose acetate electrophoresis. Reference test results were not available to the HemeChip users. Similarly, HemeChip test results were not available to the users of the standard reference tests. Clinical validation studies presented here were performed with a fully functional, portable HemeChip prototype developed at Case Western Reserve University (Fig. 1A). A commercial product has been developed based on this technology by Hemex Health Inc. under the product name, GazelleTM(Fig. 1B). Results and Discussion: Among the total 768 tests performed with HemeChip in all test sites, 732 were valid tests, as defined by the Standards for Reporting Diagnostic Accuracy (STARD)4. HemeChip correctly identified all subjects with Hb SS, Hb SC, Hb AS, Hb AE, and Hb EE with 100% accuracy (Table 1). Nine subjects with normal Hb (Hb AA) were identified as HbSS in Nigeria. No subjects with disease were identified as normal or trait by HemeChip. Three subjects with compound heterozygous Hb Sβ-thalassemia (2 subjects with Hb Sβ+-thalassemia, 1 subject with Hb Sβ0-thalassemia) were identified as Hb SS. Sensitivity was 100% for all Hb types tested. Specificity was 98.7% for Hb SS versus other Hb types, and 100% for all other Hb types tested. HemeChip displayed an overall diagnostic accuracy of 98.4% in comparison to standard reference methods for the Hb variants tested in all clinical testing sites (Table 1). HemeChip is a versatile point-of-care system that enables affordable, accurate, decentralized hemoglobin testing in resource-limited settings.