Clinical and Laboratory Features of Homozygous Sickle Cell Patients in Tanzania; Malaria, Infections and Cerebral Blood Flow Velocity.

Background: Significant advances have been made in the management of patients with sickle cell disease (SCD), with resultant increase in survival, most notably in the USA where 1,000 children are born with SCD every year. In contrast, in Africa, where it is estimated that 450,000 children are born with SCD every year, there has been little change in the management and minimal reduction in mortality. There is no reason to doubt that similar interventions and consequent improvements in survival can be achieved in Africa. However, the lack of resources mean that it is vital that proposed interventions are based on a clear definition of the problem.

Aims: The study attempts to define causes of morbidity and mortality in SCD in Tanzania focusing on three major areas where it is important to establish clear answers. The aims of the study are to determine the role of Plasmodium falciparum infection in precipitating crises in SCD patients, to describe the major bacterial pathogens associated with admission in SCD patients and to establish the association of increased cerebral blood flow velocities (CBFv) and cerebrovascular accidents (CVA) in SCD patients in East Africa.

Study design: This is an ongoing hospital based, prospective, descriptive cohort study in Muhimbili national hospital, Dar-es-salaam, Tanzania. Patients are seen in outpatient clinic every three months, if there is any acute event requiring hospital attendance and when admitted to the hospital.

Results: From march 2004, there have been 3,650 visits during which clinical and laboratory data has been collected on 885 (male 51.4%) patients, all homozygous for HbS on cellulose acetate electrophoresis. The mean age of the patients is 10 ± 7.2 years, (range 9 months-54 yrs), with 22.7% being under the age of 5 years and 8.28% above 20 years. The frequency of major clinical events, including fits (5.2%), stroke (1.9%) is reported. The prevalence of malaria parasitaemia in outpatients and during admission was 2.9% and 7.7% respectively. 227 patients have been admitted during this period, presenting with pain (44%), anemia (17%) and fever (15%). Transcranial Doppler ultrasonography was done in 400 patients; with 25% having a time averaged maximal mean velocity of 150 cms/second or more, suggesting stenosis.

Conclusion: This study is the initial step in describing the causes of morbidity in patients with SCD disease in Tanzania, and will form the basis of longitudinal studies that will attempt to guide interventional strategies, target research and provide insight into natural history of SCD in East Africa.