Studies of NT-proBNP testing in the emergency department and evaluation of point of care testing for NT-proBNP using the LumiraDx instrument

Introduction: The primary aim of this study was to compare the accuracy of a point-of-care instrument for analysis of NT-proBNP (NT-proBNPLumiraDx) versus conventional plasma NT-proBNP results (NT-proBNPRoche). Secondary aims were: (i) to extract all plasma NT-proBNP results from this emergency department (ED) for the year 2022 and to characterize this patient cohort; (ii) to distinguish the coefficient of variation (CV) for NT-proBNP when analyzed with NT-proBNPLumiraDx. Methods: In 142 patients NT-proBNPLumiraDx determinations were compared to NT-proBNPRoche. In 2022, a total of 8,333 NT-proBNP results were reported to the ED. These samples were routine requests for NT-proBNP from the ED at Uppsala University Hospital, Uppsala, Sweden. NT-proBNP was analyzed with the LumiraDx instrument in samples from 133 healthy blood donors, to calculate reference intervals. Results: There was a significant Spearman rank correlation between age and NT-proBNPRoche analytes (P<0.0001). The median age of the patients was 76 years [interquartile range: (IQR) 65-84 years] and median NT-proBNP value was 576 ng/L (IQR: 138-2,390). In 3,612 out of 8,333 NT-proBNP test results were 400 ng/L or lower. The median CV for the NT-proBNPLumiraDx was 2.2% (range 0.1-5.2%). Conclusion: There was a strong Deming correlation between the two NT-proBNP methods: NT-proBNPLumiraDx = 1.025x NT-proBNPRoche + 9.51; r = 0.982). NT-proBNP is an important analyte for the emergency department. The strong correlation between the two NT-proBNP assays indicates that the NT-proBNPLumiraDx could be used in the emergency department for point-of-care testing. This finding strongly supports the clinical importance of our findings.