Evaluation of Analytical Performances and Comparison of 3 NT-proBNP Assays for Diagnosing Heart Failure

Reference intervals for high sensitivity cardiac troponin I and N-terminal pro-B-type natriuretic peptide in children and adolescents on the Siemens Atellica

OBJECTIVES

The cardiac biomarkers high sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are utilised in paediatric healthcare for the diagnosis and prognostic assessment of many conditions including myocarditis, congenital heart disease, multisystem inflammatory syndrome in children (MIS-C) and heart failure. However, the standardised age-related reference intervals, 99th percentile cut-offs and clinical guidelines are not available, making the interpretation of these biomarkers challenging. This study aimed to generate normative data in a paediatric cohort for the Siemens Atellica® IM 1300 analyser.

METHODS

Residual plasma samples were collected from children aged up to 17 years attending primary care and out-patient settings and with no apparent evidence of cardiac dysfunction, renal dysfunction or other confounders. Reference intervals were generated using the 2.5th-97.5th percentiles, and 99th percentile cut-offs determined according to CLSI EP28-A3c.

RESULTS

Statistical analysis revealed that partitioning was not required for gender for either biomarker. The reference interval for hs-cTnI for children aged one month to 16 years (n=292, 146 females and 146 males) was <14 ng/L with a 99th percentile cut-off of 19 ng/L. The reference interval for NT-proBNP for children aged one month up to one year was <714 ng/L (n=14) and for children aged 1-16 years (n=339) was <295 ng/L.

CONCLUSIONS

This is the first paediatric reference interval data generated on the Siemens Atellica® solution. These reference intervals and 99th percentiles will inform clinical decisions in the paediatric cardiology setting.

Evaluation of a New NT-proBNP Immunoassay on an Automated Core Laboratory System

BACKGROUND

Heart failure remains a major cause of morbidity and mortality despite improvements in treatment. This study aimed to evaluate the Alere N-terminal pro B-type natriuretic peptide (NT-proBNP) immunoassay on the Abbott Alinity i platform.

METHODS

The analytical performance including precision, linearity, limit of quantitation (LOQ), carryover, dilution-recovery, and stability was evaluated. A method comparison between the Abbott Alere NT-proBNP assay and Roche Elecsys proBNP II assay was performed using 70 residual plasma samples.

RESULTS

Total imprecision was 4.1%, 3.5%, and 2.3% for low (120.9 ng/L), medium (333.9 ng/L), and high (4767.4 ng/L) QC levels, respectively. The manufacturer's claimed LOQ of 8.3 ng/L was verified. Method comparison between the Alere NT-proBNP assay and the Elecsys proBNP II assay showed good agreement between assays with an R value of 0.998, a slope of 1.05 (95% CI, 1.03-1.06), and an intercept of 45.81 (95% CI, -46.6.84 to 138.22). The Bland-Altman plot showed an absolute bias of 250 ng/L or 6.02%. Subrange analysis (NT-proBNP <2000 ng/L) showed good agreement with an R value of 0.998, a slope of 1.04 (95% CI, 1.02-1.06), and an intercept of -4.83 (95% CI, -26.95 to 17.28), with a mean bias of 26 ng/L or 3.2%. The stability of NT-proBNP was also verified in lithium heparin plasma samples stored at 4°C over a 7-day period. Hemolysis and lipemia interference thresholds were verified, but icterus impacted NT-proBNP recovery by >20% at low analyte concentrations.

CONCLUSIONS

The Alere NT-proBNP assay demonstrated acceptable analytical performance and very good clinical concordance with the Elecsys proBNP II assay.

Diseases associated with prematurity in correlation with N-terminal pro-brain natriuretic peptide levels during the early postnatal life

The aim of this observational study was to investigate the influence of different typical preterm diseases on NT-proBNP serum levels in the early postnatal period of life of a preterm infant. NT-proBNP levels of 118 preterm infants born ≤ 31 weeks GA were determined at the first week of life, after 4 ± 1 weeks of life, and at a corrected gestational age of 36 + 2 weeks. Relevant complications with a possible influence on NT-proBNP values in the first week of life such as early neonatal infection, hemodynamically significant PDA (hsPDA), early pulmonary hypertension (early PH), and intraventricular hemorrhage (IVH) were evaluated; at 4 ± 1 weeks of life, bronchopulmonary dysplasia (BPD), BPD-related pulmonary hypertension (BPD-associated PH), late infection, IVH, and intestinal complications were evaluated. At a corrected gestational age of 36 ± 2 weeks, we examined the effect of retinopathy of prematurity (ROP), BPD, BPD-associated PH, and late infection on NT-proBNP levels. In the first days of life, only the isolated occurrence of hsPDA resulted in significantly increased NT-proBNP levels. In multiple linear regression analysis, early infection remained independently associated with NT-proBNP levels. At 4 ± 1 weeks of age, the isolated presence of BPD and BPD-related PH resulted in increased levels, and the effect remained significant in the multiple regression analysis. At a corrected gestational age of 36 ± 2 weeks, infants with relevant complications at this final evaluation time tended to have lower NT-proBNP values than our exploratory reference values.    Conlusion: NT-proBNP in the first week of life seems to be mainly influenced by an hsPDA and infection or inflammation. BPD and BPD-related PH are the most important factors influencing NT-proBNP serum levels in the first month of life. When preterm infants reach a corrected GA of 36 ± 2 weeks, chronological age rather than complications of prematurity must be considered when interpreting NT-proBNP levels. What is Known: • Several complications associated with prematurity, such as hemodynamically significant PDA, pulmonary hypertension, bronchopulmonary dysplasia, and retinopathy of prematurity, have been shown to influence NT-proBNP levels in preterm infants in their early postnatal life. What is New: • Hemodynamically relevant PDA is a major factor in the increase of NT-proBNP levels in the first week of life. • Bronchopulmonary dysplasia and pulmonary hypertension associated with bronchopulmonary dysplasia are important factors in the increase in NT-proBNP levels in preterm infants at approximately 1 month of age.