NT-proBNP as a marker of cardiopulmonary status in sickle cell anaemia in Africa.

N-terminal (NT) pro-brain natriuretic peptide (proBNP) > or =160 ng/l has a 78% positive predictive value for pulmonary hypertension and is associated with increased mortality in US sickle cell disease patients, but the importance in sickle cell disease patients in Africa is not known. In a cross-sectional study at Ahmadu Bello University Teaching Hospital, Shika-Zaria, Nigeria, we studied 133 hydroxycarbamide-naïve Nigerian sickle cell anaemia patients aged 18-52 years at steady-state and 65 healthy controls. Twenty-six percent of patients versus 5% of controls had NT-proBNP > or =160 ng/l (P = 0.0006). By logistic regression among the patients, human immunodeficiency virus seropositivity, higher serum ferritin and lower haemoglobin or higher lactate dehydrogenase independently predicted elevated NT-proBNP. After adjustment for haemoglobin concentration, elevated NT-proBNP concentration was associated with an estimated 7.8-fold increase in the odds of severe functional impairment, defined as an inability to walk more than 300 m in 6 min (95% confidence interval 1.5-32.6; P = 0.005). Similarly, elevated tricuspid regurgitation velocity was associated with an estimated 5.6-fold increase in the odds of functional impairment (95% confidence interval 1.5-21.0; P = 0.011). In conclusion, NT-proBNP elevation is common and is associated with markers of anaemia, inflammation and iron status and with severe functional impairment among sickle cell anaemia patients in Nigeria.