Impact of Sickle Cell Disease on Affected Individuals in Nigeria: A Critical Review

Sickle cell disease is an autosomal recessive disorder of the beta-globin gene, with resultant deformation of the red blood cells and variable clinical outcomes. Nigeria is recognised as the country with the highest burden of sickle cell disease globally. This study aimed at critically reviewing available literature on impact of sickle cell disease in Nigeria. A literature search was carried out on four databases, and a total of 116 articles that met the inclusion criteria were included in the critical review. It was observed that majority of the studies were carried out in South-Western part of Nigeria (47.4%), whilst the North-East had the least number of studies undertaken in this area, more than a quarter of the studies (27.6%) were related to hematologic and serologic screening. Major themes that emerged from this review were morbidity and mortality; prevalence of sickle cell disease; issues relating to blood transfusion; psychosocial impact; and anatomical dysfunction in sickle cell disease. Intervention programs from both government and non-governmental organizations aimed at reducing the burden of sickle cell disease and its socio-economic impact were identified as key to strategies aimed at overcoming challenges associated with the disease. Findings from this study also revealed that education and awareness interventions were central to reducing the prevalence of sickle cell disease in this setting.

The Epidemiology of Neurological Complications in Adults With Sickle Cell Disease: A Retrospective Cohort Study

Introduction: Risk factors for neurological complications in sickle cell disease differ in the adult and pediatric populations. Here, we focused on neurological complications in adults with sickle cell disease.

Methods: Patients were selected using the audit data from the St George's Hospital Red Cell Database. The genotyping, demographics, clinical data, and investigation findings were collected.

Results: A total of 303 patients were enrolled in the study: hemoglobin S homozygosity (HbSS) genotype 56%, hemoglobin S and C coinheritance (HbSC) genotype 35%, and hemoglobin S and β-thalassemia coinheritance (HbSβ) thalassemia genotype 9%; the mean age was 38.8 years (±13.5 SD) with 46% males. The most common neurological complication was cerebrovascular disease (n = 37, 12%) including those with ischemic stroke (10%), cerebral vasculopathy (3%), and intracranial hemorrhage (1%). Ischemic stroke was common among the HbSS genotype compared with other genotypes (8 vs. 1.6%, p = 0.001). Comparing the patients with sickle cell disease who had suffered a stroke to those who had not, there was a higher proportion of intracranial vasculopathy (p = 0.001, in particular, Moyamoya) and cognitive dysfunction (p < 0.0001).

Conclusion: Our cohort supports previous reports that the most common neurological complication in adult sickle cell patients is cerebrovascular disease. Strategies to prevent cerebral vasculopathy and cognitive impairment should be explored.

Stroke and stroke prevention in sickle cell anemia in developed and selected developing countries

This comprehensive review provides an insight into the pathophysiology, epidemiology, evaluation, and treatment of sickle cell anemia (SCA)-related stroke in developed and developing countries. Vascular injury, hypercoagulability and vaso-occlusion play a role in the pathophysiology of stroke in SCA. Transcranial Doppler ultrasound (TCD) has lowered the incidence of ischemic stroke from 11% to 1% as TCD identifies children who are at risk for stroke, providing opportunities for interventions to reduce this risk. Whereas blood exchange is indicated in acute stroke, chronic transfusions (either simple or exchange on a monthly basis) are used for primary as well as secondary stroke prevention in developed countries. Children with abnormally high TCD velocities (≥ 200 cm/s) are at high risk of stroke and might benefit from hydroxyurea or hydroxycarbamide (HU) after a period of a successful transition from chronic transfusions. Hematopoietic stem cell transplant presents a cure for SCA. Gene therapy is currently investigated and may be offered to patients with SCA who had a stroke or who are at high risk of stroke if proven efficacious and safe. However, gene therapy is not likely to be implemented in low-income countries due to cost. Alternatively, HU is utilized for primary and secondary stroke prevention in developing countries. Further expansion of TCD implementation should be a priority in those settings.

Haemoglobin oxygen saturation, leucocyte count and lactate dehydrogenase are predictors of elevated cerebral blood flow velocity in Nigerian children with sickle cell anaemia

BACKGROUND

Transcranial Doppler ultrasound (TCD) scan, which measures blood flow velocity through the time-averaged mean of maximum velocities (TAMMVs) in the internal carotid arteries and middle cerebral arteries, is a useful screening tool for predicting stroke risk in children with sickle cell anaemia (SCA).

AIM

To investigate which clinical and laboratory indices predict abnormal TCD velocity in children with SCA.

METHODS

Fifty-four SCA patients with normal TCD (TAMMV < 170 cm/s), classified as negative TCD (NTCD), and 93 patients with conditional and abnormal TCD velocities (TAMMV ≥ 170 cm/s) classified as positive TCD were recruited. The haemoglobin oxygen saturation, haematological variables, nitric oxide metabolites and lactate dehydrogenase activity of the patients were analysed.

RESULTS

The mean (SD) age was 7.16 (3.84) years (range 2-16). The median SpO₂ of the patients in the positive TCD group was significantly lower than that of the negative TCD group (p = 0.002). Multivariate logistic regression analysis indicated that the MCV [odds ratio (OR) 1.12, 95% confidence interval (CI) 1.04-1.22, p = 0.01)], MCH (OR 1.34, 95% CI 1.02-1.77, p = 0.04), leucocyte count (OR 1.26, 95% CI 1.07-1.49, p = 0.01) and lactate dehydrogenase (LDH) level (OR 1.00, 95% CI 1.00-1.01, p = 0.01) were independent predictors of high cerebral blood flow velocities.

CONCLUSIONS

These clinical and laboratory indices are characteristic of chronic hypoxia and severe anaemia and are predictors of abnormal cerebral blood flow velocity. They can be used to predict stroke risk in children with SCA when access to TCD screening is limited.

Management of sickle cell disease: a review for physician education in Nigeria (sub-saharan Africa)

Sickle cell disease (SCD) predominates in sub-Saharan Africa, East Mediterranean areas, Middle East, and India. Nigeria, being the most populous black nation in the world, bears its greatest burden in sub-Saharan Africa. The last few decades have witnessed remarkable scientific progress in the understanding of the complex pathophysiology of the disease. Improved clinical insights have heralded development and establishment of disease modifying interventions such as chronic blood transfusions, hydroxyurea therapy, and haemopoietic stem cell transplantation. Coupled with parallel improvements in general supportive, symptomatic, and preventive measures, current evidence reveals remarkable appreciation in quality of life among affected individuals in developed nations. Currently, in Nigeria and other West African states, treatment and control of SCD are largely suboptimal. Improved knowledge regarding SCD phenotypes and its comprehensive care among Nigerian physicians will enhance quality of care for affected persons. This paper therefore provides a review on the aetiopathogenesis, clinical manifestations, and management of SCD in Nigeria, with a focus on its local patterns and peculiarities. Established treatment guidelines as appropriate in the Nigerian setting are proffered, as well as recommendations for improving care of affected persons.

Hypertransfusion therapy in sickle cell disease in Nigeria

Introduction. Hypertransfusion refers to chronic blood transfusion therapy aimed at ameliorating disease complications in various haemopathies particularly the haemoglobinopathies. In sickle cell disease, hypertransfusion is aimed at maintaining patient's haemoglobin level at 10 to 11 g/dL using haemoglobin AA blood and its resultant dilutional effect on sickle haemoglobin is sustained by intermittent long-term transfusions. Aim and Objective. This paper highlights hypertransfusion and its privileged position as a secondary measure in prevention and treatment of sickle cell disease, especially in the Nigerian context. Materials and Methods. Relevant literatures were searched on PubMed, Google Scholar and standard texts in haematology and transfusion medicine. Keywords used in the search are hypertransfusion, sickle cell disease, chronic transfusion, and Nigeria. Literatures gathered were reviewed, summarized, and presented in this paper. Result. Immense clinical benefit is associated with hypertransfusion therapy including prevention of stroke and amelioration of severe sickle cell disease especially in transplant ineligible patients. Careful patient selections, appropriate blood component, and prevention of transfusion hazards as well as oversight function of an experienced haematologist are pertinent to a successful hypertransfusion therapy. Conclusion. Improved knowledge of the benefits and practice of hypertransfusion will effectively translate into improved health status even among Nigerian sickle cell disease patients.

Intellectual function evaluation of first generation immigrant children with sickle cell disease: the role of language and sociodemographic factors

Background

Sickle Cell Disease (SCD) is the most common genetic disease worldwide. Neurological events are among the most worrisome clinical complications of SCD and are frequently accompanied by cognitive impairment. Intellectual function in SCD may vary according to genetic and environmental factors. Immigrant children with SCD are increasing at a global level and display specific health care needs. The aim of our multicenter study was to describe the intellectual function of first generation African immigrants with SCD and the influence of sociodemographic factors on its characteristics.

Methods

The Wechsler Intelligence Scales were administered to evaluate broad intellectual functions in children with SCD and in age-matched healthy siblings. Patients’ clinical, socio-demographic, Magnetic Resonance Imaging (MRI) and Angiography (MRA) data were correlated to intellectual function scores.

Results

68 children, mean age 8.95 years were evaluated. 72% spoke three languages, 21% two. FSIQ was <75 in 25% of the children. Mean VIQ was lower than PIQ in 75%. Mean verbal subtest scores were lower than performance scores. Female gender, number of languages spoken at home and mother’s employment were associated with single subtest performances (p < 0.05). MRA was abnormal in 73.4% and MRI in 35.9%. No significant correlation was established between silent lesions and intellectual function, even if patients with lesions performed worse. Fifteen siblings performed better than patients on cognitive domains, including language (p < 0.05).

Conclusions

Immigrant bilingual children with SCD seem to display a rate of cognitive impairment similar to their monolingual counterparts but a more pronounced and precocious onset of language difficulties. Adjunctive tests need to be considered in this group of patients to better define their specific deficits.