Sickle Cell Disease: Reappraisal of the Role of Foetal Haemoglobin Levels in the Frequency of Vaso-Occlusive Crisis.

BACKGROUND Foetal haemoglobin has been implicated in the modulation of sickle cell crisis. Its level is generally inversely proportional to the severity of sickle cell disease (SCD) for a given sickle cell phenotypes. The main aim of therapy for vaso-occlusive crisis (VOC), which is the hallmark of SCD, is to reduce the chances of sickling through the prevention of polymerization of HbS. One way of preventing this polymerization is by increasing foetal haemoglobin levels. OBJECTIVES To determine the relationship between HbF levels and the frequency of crisis in SCD patients in Ghana. METHOD A longitudinal retrospective survey covering a period of 30 months was carried out on adult SCD patients at the Sickle Cell Clinic of the Korle-Bu Teaching Hospital. RESULTS Eighty-three adults aged 15 to 65 years made up of 40 males and 43 femalea were studied. Analysis of variance (ANOVA) gave significant results in Hb and HbF levels. Higher HbF levels were positively related to less frequent crisis and were significantly high in SCD patients than in controls. HbF effects on the clinical manifestations on SCD were variable. CONCLUSION Threshold values of HbF play a role in reducing the frequency of vaso-occlusive crisis in SCD patients and this finding contributes to the body of available literature on SCD severity. However our work does not give the apparent threshold level of helpful HBF Level in SCD.