BNP assay on ADVIA Centaur (Bayer HealthCare): correlations with Triage® technique (Biosite) and etiologic application to the diagnosis of a dyspnea

The measurement of plasmatic BNP is used in the diagnosis, the monitoring and the prognostic in patients with known or suspected heart failure of the left ventricule. The BNP measurement is now available on ADVIA Centaur (Bayer HealthCare). We first tested the stability of BNP on glass EDTA sample; then compared Bayer’s technical method with that of Triage BNP test (Biosite). We presented a stratification of the BNP rate in relation to NYHA (New York Heart Association) clinical class over 79 patients. In order to assess the contribution of the BNP in diagnosis, this test was realized on 76 patients presenting a dyspnea. Using the data of the ROC curve, we define a threshold of 100 ng/l differentiating pulmonary dyspnea and cardiac ones. The final clinical diagnosis defines the “gold standard” of our study. The BNP measurements were made afterwards without any knowledge of the diagnosis. Based on BNP, we observed an improvement in the diagnosis of 10.5% (8/76): rate of BNP similar to that of final diagnosis, which is itself different from first diagnosis. 67.1% (51/76) of the entrance and identical to the final diagnosis are confirmed by BNP measurement. We notice 6.6% (5/76) false negative results: BNP concentration less than 100 ng/l for heart cardiac final diagnostic; and 15.8% (11/76) false positive results: BNP concentration higher than 100 ng/l for patients with a pulmonary disease. For BNP concentration higher than 400 pg/ml, cardiac etiologic diagnosis must be kept.