Association Between Anaemia and N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP): Findings from the Heart and Soul Study

BACKGROUND: Anaemia is associated with elevated levels of natriuretic peptides. Whether the association of anaemia with natriuretic peptides is independent of other cardiovascular risk factors is unclear. METHODS: This was a cross-sectional study of 809 ambulatory patients with coronary heart disease (CHD) and no history of heart failure (HF). We evaluated the extent to which the relationship between haemoglobin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) was explained by differences in cardiovascular risk factors, inflammation, and kidney dysfunction. RESULTS: Of the 809 participants, 189 (23%) had anaemia (haemoglobin <13 g/dL). Haemoglobin (as a continuous variable) was inversely associated with log NT-proBNP (beta coefficient -.28, p<.0001). This association was considerably attenuated after accounting for cardiovascular risk factors, C-reactive protein, and kidney dysfunction. However, haemoglobin remained independently associated with log NT-proBNP even after adjustment for these variables (beta coefficient -.11, p=0.0003). Each 1 g/dL decrease in haemoglobin was associated with a 20% greater odds of having NT-proBNP in the highest quartile. CONCLUSIONS: The relationship between anaemia and NT-proBNP is largely explained by differences in cardiovascular risk factors, ventricular function, myocardial ischaemia, inflammation, and kidney function. Nonetheless, haemoglobin appears to be inversely associated with NT-proBNP even after adjustment for these risk factors.