Abstract:

Background: Sickle cell anemia (SCA) is associated with several major complications including cerebral vascular diseases such as stroke, with 11% being affected before the age of 20 years. In Northwestern Tanzania, the prevalence of stroke among children living with SCA under the age 15 years is 16.9%. Due to the absence of routine screening modalities by using Transcranial Doppler Ultrasound (TCD) and provision of preventive prophylaxis measures such as chronic blood transfusion, a higher risk of stroke might be prevalent in this population in our setting. TCD has led to the reduction of stroke prevalence by 92% following introduction of prophylactic blood transfusion for those with abnormal TCD. Despite the benefits of screening, TCD has low positive predictive value with 60% among those who screened positive for risk of stroke end up not developing stroke. Additional factors such hemoglobin level have been studied for identification of those at risk of stroke which can be used as adjuvant tools for clinical guidance in preventive measures of stroke.

Methods: This was a cross section study, which enrolled 267 SCA children aged 2 to 16 years attending Bugando Medical Centre Pediatric Sickle Cell Clinic from July 2019 to June 2020. Assessment of factors associated with elevated TCD included a clinical history of stroke in sibling, death history in sibling, oxygen saturation in room air, blood pressure (Systolic and Diastolic), hemoglobin level and total white blood cell count. TCD was done by accessing transtemporal window on both sides and recording the highest time average mean of maximum velocity (TAMMV) of major vessels mainly, middle cerebral artery (MCA) and distal internal carotid artery (dICA).

Results: The median age of enrolled was 6.6 (IQR: 4-9) years. The prevalence of elevated TCD (>170cm/s) was found to be 21% (56/267). By multivariate logistic regression, low oxygen saturation in room air, p-value = 0.037, OR 0.92 [95% CI 0.85-0.10] and low hemoglobin level, p-value=0.001, OR 0.57 [95% CI 0.41-0.79] were statistically significantly associated with elevated TCD among children living with SCA.

Conclusion: A proportion of children with elevated TCD were detected, which is associated with low hemoglobin and low oxygen saturation. These factors seen in this study warrants their incorporation in the screening of risk of stroke in children with SCA aged 2 to 16 years.