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.

Prevalence and risk factors for pulmonary artery systolic hypertension among sickle cell disease patients in Nigeria.

Pulmonary artery systolic hypertension is common and associated with increased mortality among adult sickle cell disease (SCD) patients in the United States. Although the prevalence of SCD is highest in sub-Saharan Africa, the frequency of pulmonary artery systolic hypertension and the risk factors for the development of pulmonary hypertension have not been reported from Africa. We studied 208 hydroxyurea naïve Nigerian SCD patients at steady state and 94 healthy controls. Pulmonary artery systolic hypertension was defined prospectively as tricuspid regurgitant jet velocity > or =2.5 m/sec. Results were compared with a previously published US prospective SCD cohort. Only 7% of Nigerians compared with 46% of US adults with SCD were >35 years. Tricuspid regurgitant jet velocity was > or =2.5 m/sec in 25% of Nigerian SCD patients. Higher jet velocity was associated with greater serum globulin (P = 0.002), blood urea nitrogen (P = 0.019) and lactate dehydrogenase concentrations (P = 0.026) and with inability to walk >300 m in 6 min (P = 0.042). Compared with the US cohort, Nigerian patients had more hemolysis as indicated by lower hemoglobin and higher lactate dehydrogenase concentrations (P < or = 0.003). Pulmonary hypertension is common among Nigerian SCD patients. The public health implication of this finding is significant considering the potential number of individuals at risk for this complication. Better understanding of the long term outcome of pulmonary hypertension and causes of death in SCD and the institution of preventive measures are major public health challenges for Africa. The inclusion of African sites in sickle cell pulmonary hypertension clinical trials should be encouraged.