Comparison of Patients from Nigeria and U.S.A. Highlights Modifiable Risk Factors for Sickle Cell Complications

To identify factors that affect manifestations of sickle cell anemia (SCA), we compared patients 11-30 years of age from University of Ibadan, Nigeria (n=214) and University of Illinois at Chicago, U.S.A. (n=209). Paralleling findings in the general populations of the two countries, Chicago patients were more often overweight or obese defined by CDC Guidelines (Age<18: 6% vs. 3%, P=0.02; Age≥18: 25% vs. 3%, P<0.0001) and more often had elevated blood pressure defined by NHLBI Guidelines (Age<18: 16% vs. 3%, P=0.02; Age≥18: 47% vs. 17%, P<0.0001). Ibadan patients less often had received pneumococcal vaccination (Age<18: 0% vs. 88%, P<0.0001; Age≥18: 1% vs. 91%, P<0.0001) or hydroxyurea therapy (Age<18: 7% vs. 44%, P<0.0001; Age≥18: 3% vs. 46%, P<0.0001). Consistent with lower rates of elevated blood pressure and increased body mass index (BMI), stroke history was less frequent in Ibadan patients ≥ 18 years old (2% vs. 24%, P<0.0001). Furthermore, in combined analyses, systolic and diastolic blood pressure directly correlated with BMI, and elevated weight status independently associated with history of stroke (OR 2.7, P=0.019). In conclusion, our findings are consistent with the possibility that higher values for BMI and blood pressure in Chicago SCA patients may contribute to an increased risk of stroke and highlights the need for measures to reduce these risk factors. On the other hand, in Ibadan patients, lower pneumococcal vaccination and hydroxyurea therapy rates highlight the need for more improved vaccination coverage and for studies to define the role of hydroxyurea therapy in Africa.