LumiraDx INR Test: Laboratory Accuracy Assessment with the ACL Elite and Sysmex Reference Methods

The LumiraDx Platform is a novel, point of care in vitro diagnostic system that can be used for INR testing with fresh capillary whole blood by direct fingerstick application or using a transfer tube.

The evaluation of the accuracy and precision of the CE marked LumiraDx INR test, compared to a laboratory reference method, the IL ACL Elite Pro has been demonstrated in the recent OPTIMAL study ^1,2 where a strong correlation was seen.

The LumiraDx Instrument displays the results equivalent to laboratory plasma measurements as the International Normalised Ratio (INR). Each Test Strip Lot is calibrated to a reference that is traceable to the WHO International Reference standard rTF/09. It has been shown that comparing results obtained with the LumiraDx INR Test to those obtained with common laboratory reagents shows that the LumiraDx INR Test correlates well with ACL Elite Pro with HemosIL RecombiPlasTin 2G.

A sample comparison was carried out to demonstrate the performance of IL ACL Elite Pro (ACL) and Sysmex CS instruments (CS-2100 and CS-5100) as reference methods for the LumiraDx INR assay.

The sample collection was designed to compare the INR results from patients attending anticoagulation clinics and determined by three different INR Test methods: LumiraDx INR test (capillary blood sample), ACL Elite (plasma) and Sysmex (plasma).

101 blood samples were collected from patients attending anticoagulation clinics during which their LumiraDx INR and ACL Elite Pro INR values were established. Frozen plasma samples which were collected during routine calibration³ in sodium citrated tubes were sent to four separate laboratories for INR testing using the Sysmex laboratory analyser. The four laboratories were the University Hospital Hairmyres, University Hospital Wishaw and University Hospital Monklands in the Lanarkshire region of Scotland and one in London, The Doctors Laboratory (TDL).

At Monklands and Wishaw, the samples were analysed using the Sysmex CS-2100 instrument. At TDL and Hairmyres the samples were analysed using the Sysmex CS-5100 instrument. All the systems were using Siemens Dade Innovin reagent following standard hospital laboratory procedures.

Passing-Bablok regression was used to perform a method comparison between the ACL Elite.

Pro and Sysmex instruments for calculating INR. The same method was also used to perform a method comparison between the LumiraDx INR.

Assay and Sysmex instruments. As the samples used in the study were clinical calibration results, paired results for LumiraDx and ACL were available for each sample.

Data was returned to LumiraDx (Dumyat, Stirling) where statistical analysis was performed. Passing-Bablok regression was used in a method comparison of data obtained on the ACL Elite Pro and Sysmex analysers. The same method was also used to perform a method comparison between the LumiraDx INR Assay and Sysmex instruments.

Analysis confirmed a good agreement between the LumiraDx INR test results (capillary blood sample) and those obtained from plasma samples using both the ACL Elite and also the Sysmex CS 2100/5100. Furthermore, data from the Sysmex CS 2100/5100 was demonstrated to correlate across 4 independent hospital laboratories.

Previous data from the OPTIMAL study also demonstrated that a strong correlation between the LumiraDx instrument INR test with the ACL Elite Pro reference method in samples from 366 patients^4:

The LumiraDx INR Test, ACL Elite Pro and the Sysmex CS2100/5100 returned comparable results, and agree closely when compared across 4 independent sites.