Performance Evaluation of the Quantitative Point-of-Care LumiraDx d-Dimer Test

INTRODUCTION: Fibrin degradation product D-dimer can be a valuable indicator for venous thromboembolism (VTE). The use of D-dimer testing in primary care settings can be limited by restricted access to laboratory services. This performance evaluation compares a quantitative, point-of-care (POC) D-dimer assay (LumiraDx D-Dimer Test) with a reference laboratory-based D-dimer assay. METHODS: Plasma samples from patients presenting to secondary care in the UK, USA, and Germany were analyzed centrally using the LumiraDx D-Dimer Test and the reference test (bioMérieux VIDAS D-Dimer Exclusion II immunoassay). Method comparison used Passing-Bablok regression analysis with pre-specified equivalence criteria of r ≥ 0.9 and slope of 0.9-1.1. The NOVEL-3 study (NCT04375982) compared equivalency of fingerstick, venous blood (VB), and plasma samples from the same patient, tested at US primary care clinics next to the patient using the POC LumiraDx D-Dimer device. Measurements obtained from fingerstick and VB samples were compared with results from plasma samples, using Deming regression. The healthy reference range was determined using plasma samples of healthy volunteers, collected by commercial suppliers in Germany and the USA, which were analyzed centrally using the LumiraDx D-Dimer Test and the reference test. RESULTS: The LumiraDx D-Dimer Test demonstrated agreement with the bioMérieux VIDAS D-Dimer Exclusion II immunoassay for plasma samples (r = 0.923, slope of 1.016, n = 1767). There was good agreement between fingerstick/VB samples and plasma samples (r = 0.980-0.986, n = 93) measured using the LumiraDx D-Dimer Test. Overall error rates were 1.8%. The healthy reference range 90% percentile for D-dimer was calculated as 533 µg/l fibrinogen equivalent units (FEU). CONCLUSIONS: The quantitative LumiraDx D-Dimer Test is easy to use and can accurately measure D-dimer levels in a range of blood sample types, including fingerstick samples, which could improve assessment of VTE cases in community and hospital near-patient settings.