Foetal Haemoglobin and Disease Severity in Nigerian Children with Sickle Cell Anaemia

Background: Foetal haemoglobin (HbF) is a major modifying factor influencing sickle cell disease (SCD) severity. Despite this, HbF estimation is not routinely done in Nigeria. The relationship between HbF and SCD severity among affected children is also poorly studied. Methods: In this descriptive cross-sectional study, we determined the relationship between steady state HbF levels and disease severity of Nigerian children aged 1 - 15 years with homozygous SCD. For each child, the socio-demographic characteristics and SCD clinical severity were determined. The latter was assessed based on the frequency of significant painful episodes, blood transfusion, and hospitalisation in the preceding 12 months; lifetime cumulative incidence of SCD-related complications; the degree of splenic and hepatic enlargement; current haematocrit and leucocyte count. Foetal haemoglobin levels were quantified with high-performance liquid chromatography. Results: The mean HbF level of the 105 children with SCA was 9.9 +/- 6.0%. Male had significantly lower mean HbF levels than females, 8.0 +/- 5.6% vs. 12.2 +/- 5.8% (p < 0.001). None of the children had severe disease. However, the 32 children with moderate disease had significantly lower mean foetal haemoglobin levels than the 73 with mild disease (7.7 +/- 5.6% vs 10.8 +/- 6.0% respectively). The mean HbF level was also significantly lower in children who had a history of acute chest syndrome and stroke compared to those without these complications, p = 0.002 and 0.010 respectively. Conclusion: Children with SCA who had a moderate disease and those with a history of life-threatening complications such as stroke and acute chest syndrome had significantly low HbF levels. Therefore, it is recommended that facilities for early quantification of foetal haemoglobin and HbF inducement were made available to reduce the morbidity and mortality among these children.