Key result
LumiraDx point-of-care INR assay shows strong agreement with standard laboratory testing, achieving ~0.94 correlation.
Why the study?
INR monitoring typically relies on laboratory-based services, which can limit access to rapid monitoring and cause diagnostic delays that point-of-care testing may address.
Does the LumiraDx INR point-of-care assay provide accurate and precise INR measurements compared to standard-of-care laboratory testing in patients on warfarin therapy?
Cross-Sectional (n=348)
Yes
Does the LumiraDx INR point-of-care assay provide accurate and precise INR measurements compared to standard-of-care laboratory testing in patients on warfarin therapy?
Effect estimate: Correlation coefficient 0.94 (95% CI 0.9267-0.9497)
The LumiraDx point-of-care INR assay provides reliable results for values below 3.5, offering a rapid alternative to laboratory testing for most patients on warfarin.
May support LumiraDx for rapid INR monitoring in warfarin patients; leaves open prospective outcome validation before practice change.
Background: The International Normalized Ratio (INR) monitors anticoagulant treatment but relies on laboratory-based services. This could limit access to rapid monitoring and increase the diagnostic delay, both of which may be addressed by point-of-care testing (POCT). This study investigated the LumiraDx POC platform for INR monitoring. Methods: INR was measured on recalcified residual venous (n = 94) specimens from Chris Hani Baragwanath Hospital and capillary blood specimens (n = 254) from consenting enrolled participants at Charlotte Maxeke Johannesburg Academic Hospital Anticoagulation clinic, Johannesburg, South Africa. Standard-of-care (SOC) INR was measured on sodium-citrated venous blood using the Sysmex-CS2500 platform (Siemens Healthcare) and Neoplastin-R (Roche Diagnostics and Diagnostica Stago, Paris, France) within 2 h post-venipuncture. Within run, precision was measured using 2 LumiraDx control levels. The statistical agreement of paired INR measurements was also stratified by dosing decision. Results: The precision was within the manufacturer’s claim for controls (level 1%CV: 3.63, level 2%CV: 2.24). Accuracy analysis showed a moderate overall agreement compared to the SOC INR results with a correlation coefficient of 0.94 (95% Cl, (0.9267 to 0.9497)). The overall precision (ρ > 0.9) and accuracy (Cb = 0.9842) were good with an absolute bias of 0.07. The 95% confidence intervals for the slope and intercept did not include 1.00 and 0.00, respectively; however, the total calculated error was within the minimal acceptable limits. Conclusion: The LumiraDx INR Test showed a good performance compared to laboratory-based testing and provided opportunity for rapid and patient-centric care. Owing to an increasing positive bias for INR > 3.5, confirmation with laboratory INR measurements may be required.
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Munir et al. (2024) conducted a cross-sectional in Patients receiving warfarin therapy (n=348). LumiraDx INR point-of-care assay vs. Standard-of-care laboratory INR testing was evaluated on Overall statistical agreement (correlation coefficient) between LumiraDx and standard-of-care INR results (Correlation coefficient 0.94, 95% CI 0.9267-0.9497). The LumiraDx INR point-of-care assay demonstrated moderate overall agreement with standard-of-care laboratory testing, showing a correlation coefficient of 0.94.
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