Sickle cell anemia in sub-Saharan Africa: advancing the clinical paradigm through partnerships and research.

Objective: To summarize prevalence data on the neurologic complications of sickle cell disease (SCD) in Africa. Methods: We searched EMBASE, PubMed, and African Index Medicus to identify all relevant articles published from inception to May 31, 2016. Each study was reviewed for methodologic quality. A random-effects model was used to estimate the prevalence of neurologic complications of SCD across studies. Results: Thirty-one studies were included. Methodologic quality was high or moderate in 90% of studies. Stroke, conditional and abnormal cerebral blood flow, seizures, and headache were the complications most frequently reported, with overall prevalence rates of 4.2%, 10.6%, 6.1%, 4.4%, and 18.9%, respectively. Some complications, like silent brain infarcts, peripheral neuropathies, neurocognitive deficits, or moyamoya disease, have been rarely or not studied at all in the African setting. Incidence data were scarce and of poor quality. Conclusions: The burden of neurologic complications of SCD is important in Africa and most likely underestimated. A better evaluation of this burden requires larger prospective studies using standard up-to-date screening methods. Accessibility to diagnostic tools such as neuroimaging, transcranial Doppler, EEG, and neuropsychological evaluation, as well as to preventive and therapeutic interventions and trained health care providers, should be improved in routine clinical practice.

https://n.neurology.org/content/neurology/89/14/1516.full.pdf

Neurologic complications of sickle cell disease in Africa: A systematic review and meta-analysis.

Sickle cell disease (SCD) is an inherited hemoglobinopathy caused by a mutation in the sixth amino acid of the β-globin gene (HBB). It is the most common serious genetic diseases in childhood, affecting approximately 1 in 2500 births and 100 000 individuals in the USA, in addition to 300 000 new cases globally each year. Central nervous system injury is the most debilitating frequent complication of SCD and includes stroke, silent cerebral infarct (SCI), and cognitive impairment. Among children with sickle cell anemia (HbSS), 11% had a stroke by age 18 years before the implementation of transcranial Doppler screening. SCI is identified in 27% of children with HbSS by their 5th birthday. Children who develop SCI have greater cognitive impairment compared with either children with HbSS without SCI or siblings without SCD. A recent study of adults demonstrated significant cognitive dysfunction, even in participants with apparently mild SCD.

Sickle cell disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

Epidemiology of Stroke in Sickle Cell Disease.

/pdf/hydroxyurea-to-lower-transcranial-doppler-velocities-and-5a9aljy4fj.pdf

Hydroxyurea to lower transcranial Doppler velocities and prevent primary stroke: the Uganda NOHARM sickle cell anemia cohort

Background: Stroke is a life-changing, debilitating complication of sickle cell disease (SCD). Previous studies had recorded high stroke prevalence amongst this group of patients. Nigeria has a large population of people affected by this condition and this study aims to assess the stroke prevalence in this large population. Methodology: Stroke prevalence data from 14 physicians working in 11 tertiary health centres across the country was collated by doctors using the sickle cell registers and patient case notes. This data was then collated and used to obtain the overall stroke prevalence in adult and children. Results: The stroke prevalence in sickle cell disease patients in Nigeria was observed to be 12.4 per 1000 patients. Prevalence in the adult patients was 17.7 per 1000 patients and 7.4 per 1000 patients in children. Twenty three percent of the affected patients had more than stroke episode. Conclusion: The stroke prevalence in Nigeria is lower than previously recorded rates and further studies will be required to investigate other factors which may play a role.

/pdf/stroke-prevalence-amongst-sickle-cell-disease-patients-in-2pwuu66b60.pdf

Awele Chukwurah

Papers

Stroke prevalence amongst sickle cell disease patients in Nigeria: a multi-centre study