Defining the Clinical Spectrum of Sickle Cell Disease in Tanzania: A Clinico-Epidemiological Study

Makani, Julie (2011). Defining the Clinical Spectrum of Sickle Cell Disease in Tanzania: A Clinico-Epidemiological Study. PhD thesis The Open University.



Introduction: The burden of Sickle Cell Disease (SCD) in Africa is high; having over 75% of annual global births and mortality reaching 95% in childhood. Introduction of interventions, which could prevent 70% of deaths, have been limited because of lack of local evidence. This study described the clinical spectrum of SCD in Tanzania as the first step in providing evidence to guide targeted interventions.

Methods: SCD patients attending Muhimbili Hospital in Dar-es-Salaam, Tanzania were recruited between 2004 and 2009. Prospective surveillance of clinical and laboratory information was done at outpatient clinic and during hospitalisation. Specific investigations included blood cultures on all hospitalised SCD patients, Transcranial Doppler (TCD) ultrasonography to measure cerebral blood flow velocity (CBFv) and HPLC to measure levels of foetal haemoglobin (HbF). The outcomes of interest were death, hospitalisation, malaria, bacteraemia and stroke.

Results: 1,725 SCD patients [mean age 9.7 (SD 7.9) years; 10% below 2 years] were enrolled with information recorded from 14,000 visits during the study period. 12% of enrolled SCD patients were lost to follow up and 23% of 86 deaths occurred at the hospital. The mortality was 2 deaths/100 person years of observation (PYO); highest under 5 years and independently associated with low haemoglobin (Hazard ratio 0.7 95%CI 0.6-0.8; p0.01). 504 (29%) of the SCD cohort were hospitalised with pain, fever and anaemia as the commonest cause of hospitalisation. SCD patients had less malaria than non-SCD patients at clinic (OR, 0.46; 95% CI, 0.25-0.94; P = .01) and during hospitalisation (OR, 0.53; 95% CI, 0.32-0.86; P = .008). In SCD patients, prevalence of malaria was higher during hospitalisation and associated with severe anaemia and death. 43 out of 890 hospitalisations had bacteraemia (4.8%) with Staphylococcus aureus (28%), non-typhii Salmonella (21%) and Streptococcus pneumoniae (7%) as the most common organisms. The mean CBFv in 372 patients (2 - 16 years) was 132 cm/sec with CBFv > 200cm/sec occurring in 40 (10%) patients. The incidence of stroke was 0.3 per 100PYO; associated with sickle haemoglobin and reticulocyte count but not with CBFv. The mean HbF level in 1,669 SCD patients was 6.3 (SD 4.7) % with no association with mortality and hospitalisation.

Conclusion: This study has highlighted the burden of disease to individuals and health system. The findings have important implications for policies to improve healthcare as well as identifying areas for further research.

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