Foetal haemoglobin and disease severity in sickle cell anaemia patients in Kampala, Uganda

BACKGROUND: Sickle cell anaemia (SCA) is a major chronic health problem in Uganda. In patients with SCA, the level of foetal haemoglobin (HbF) has been found to be important in influencing the clinical course of the disease. Thus populations with high levels of HbF like those in Saudi Arabia have been described as having a milder clinical course with fewer complications as compared to populations with lower levels. Disease modifying drugs can increase the Hb F levels and modify the presentation of SCA. METHODS: This was a cross sectional study in which we determined foetal haemoglobin levels and examined the relationship between HbF levels and disease severity in SCA patients in Mulago Hospital, Kampala, Uganda. We consecutively enrolled 216 children aged 1 year to 18 years with SCA attending the Sickle Cell Clinic at Mulago Hospital whose guardians had given consent. The history included age at onset of initial symptoms and diagnosis, number of hospitalisations and blood transfusions and other complications of SCA (cardiovascular accidents, avascular hip necrosis and priapism). A detailed physical examination was performed to assess the current state and help describe the disease severity for each patient. Blood samples were drawn for HbF levels. HbF levels ≥10% was defined as high. RESULTS: Of the 216 children, (80) 37% had HbF levels ≥10%. Significant correlations were observed between HbF level and several clinical parameters independent of age including age at diagnosis (p value 0.013), number of hospitalisations (p value 0.024) and transfusions (p value 0.018) since birth. CONCLUSION: A third of the children with SCA attending the Sickle cell clinic in Mulago Hospital have high HbF levels. Higher HbF level is associated with later onset of symptoms and presentation, and less severe disease characterised by fewer hospitalisations and blood transfusions. We suggest HbF levels should be determined at initial contact for patients with SCA to guide counselling and identify those who may need closer follow up and consideration for disease modifying drugs.