Multi-center validation of the Response Biomedical Corporation RAMP® NT-proBNP assay with comparison to the Roche Diagnostics GmbH Elecsys® proBNP assay

Background: NT-proBNP measurements aid in the evaluation of patients with suspected heart failure (HF) and may facilitate risk stratification in patients with HF and acute coronary syndrome (ACS). Point-of-care (POC) assays may provide more timely results and potentially improve patient outcomes. Methods: We evaluated the analytical performance of the Response Biomedical Corporation whole blood RAMP amino-terminal pro-B type natriuretic peptide (NT-proBNP) POC assay compared to the Roche Elecsys proBNP (NT-proBNP) assay. Results: Intra-day and total imprecision (% CV) ranged from 5.5% to 10.3% at 140, 449 and 1675 ng/L. The lowest concentration that yields a 20% CV was 57 ng/L. The lower limit of detection was 18 ng/L. The upper limit of linearity was validated to 23,428 ng/L with an average recovery of 95%. Correlation by Passing and Bablok regression yielded RAMP = 1.01 Elecsys + 14.6, r = 0.98 (n = 540; range of Elecsys values < 5 to > 35,000). Concordance of RAMP versus Elecsys using cut-offs of 125 ng/L for subjects < 75 years and 450 ng/L for subjects ≥ 75 was 92% (95% CI 89-94%) for a group consisting of 127 apparently healthy individuals and 208 non-healthy subjects without HF, and 99% (95% CI 97-100%) for patients with HF, using the New York Heart Association (NYHA) functional classification. Overall, 80%, 87%, 97% and 100% of the RAMP results and 77%, 85%, 96% and 100% of the Elecsys results were greater than the age appropriate cut-off for NYHA I, II, III or IV groups. For both the RAMP and Elecsys results, the median NT-proBNP value was statistically correlated (increasing) with NYHA I, II, III or IV groups, respectively (p < 0.0001), with no significant difference between the two methods. Conclusions: The POC Response Biomedical RAMP NT-proBNP assay provides comparable results that measured on the FDA cleared Roche Elecsys central laboratory platform.