Arterial blood pressure in adult Nigerians with sickle cell anemia

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.

ATR1 Angiotensin II Receptor Reduces Hemoglobin S Polymerization, Phosphatidylserine Exposure, and Increases Deformability of Sickle Cell Disease Erythrocytes

Angiotensin II (Ang II) regulates blood volume and stimulates erythropoiesis through AT1 (ATR1) and AT2 (ATR2) receptors, found in multiple tissues, including erythrocytes. Sickle cell disease (SCD) patients present altered Ang II levels. Hemoglobin S polymerization, deformability and phosphatidylserine translocation are important features of mature erythrocytes, therefore, our hypothesis is Ang II affects these parameters and, if it does, what would be the influence of AT1R and AT2R on these effects. A polymerization assay (PA), deformability, and annexin V binding were performed in SCD erythrocytes samples adding Ang II, ATR1 antagonist (losartan or eprosartan), and ATR2 antagonist (PD123319). Through the PA test, we observed a dose-dependent polymerization inhibition effect when comparing Ang II to control. Losartan did not affect the level or the rate of Ang II inhibition, while PD123319 showed an increased level of protection against polymerization, and eprosartan brought levels back to control. Ang II was able to reduce the translocation of phosphatidylserine from the inner to the outer leaflet, a marker of eryptosis, in the presence of PD123319. Also, ATR1 showed a positive effect increasing deformability. Our data shows that ATR1 is important for maintenance of erythrocyte physiological function in SCD and for prolonging its life.

Clinical characteristics and risk factors of relative systemic hypertension and hypertension among sickle cell patients in Cameroon

Increased blood pressure (BP) has been associated with higher risk of stroke and mortality in Sickle Cell Disease (SCD). We investigated risk factors associated with Relative Systemic Hypertension (RSH) or systemic hypertension in SCD patients in Cameroon. Using R, Multivariate multinomial logistic regression modeling was used to examine the effects of the demographic, anthropometric, clinical, and laboratory factors to determine risk factors. A total of 815 individuals with SCD, including 380 (46.6%) males were analyzed. At baseline, the median age [interquartile range] was 18.0 [12.0-25.0] years, ranging from 3 to 66 years. Approximately three-quarters of the patients (n = 645; 79.1%) had normal BP, 151 (18.5%) had RSH and 19 (2.3%) had hypertension. Age (P < 0.001) and gender (P = 0.022) were significantly different across the BP categories. Weight (P < 0.001), height (P < 0.001), BMI (P < 0.001), pulse pressure (P = 0.020), history of stroke (P = 0.012), hemoglobin level (P = 0.002), red blood cell count (P = 0.031), creatinine (P < 0.001), and (estimated glomerular filtration rate) eGFR (P = 0.002) was also significantly different across the three BP categories. After adjustment, the significantly associated factors of RSH in the SCD patients were age [OR = 1.03, (95% CI = 1.01-1.06), P < 0.010], male gender [OR = 1.54, (95% CI = 1.04-2.27), P = 0.029], BMI [OR = 1.10, (95% CI = 1.04-1.17), P = 0.001]. After adjustment, the independent variables significantly associated factors of Hypertension in the SCD patients were age [OR = 1.05, (95% CI = 1.01-1.10), P = 0.034], male gender [OR = 3.31, (95% CI = 1.04-10.52), P = 0.042], BMI [OR = 1.14, (95% CI = 1.01-1.29), P = 0.027]. Creatinine was significantly associated with RSH [OR =1.31 (1.05-1.63), P = 0.016]. SCD patients with RSH or hypertension maybe at increased risk of renal dysfunction. We found relatively high prevalence of RSH and hypertension (20.8%) in SCD patients in Cameroon. Tailored Interventions that consider major risk factors (age, gender, and BMI) may lower BP pressure and prevent severe complications.

Factors associated with blood pressure variation in sickle cell disease patients: a systematic review and meta-analyses

OBJECTIVES

Blood pressure (BP) values ≥120/70 mmHg considerably increase the risk of pulmonary hypertension and renal dysfunction in Sickle Cell Disease (CSD) patients and ultimately increased morbidity and mortality. This has led to the development of the term relative systemic hypertension (RSH). RSH was defined as Systolic BP 120-139 mm Hg or diastolic BP 70-89 mm Hg, whereas systemic hypertension is defined as Systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg. Systematic identification of BP variations and risk factors in SCD patients could promote effective management. This review aimed to identify factors associated with BP variation among SCD patients.

METHODS

We searched PubMed, Scopus, Web of Science, and Google Scholar up to December 2020 with no geographical or language restrictions. Two reviewers independently screened and summarized data from eligible studies.

RESULTS

Advancing age, gender, higher body weight, hemoglobin, eGFR, triglycerides, greater hematocrit, higher blood viscosity, history of blood transfusion, and targeted variants in DRD2 and MIR4301 genes were independently associated with the risk of hypertension in SCD patients.

CONCLUSION

Interventions that consider these risk factors may potentially contribute to lower BP pressure in SCD patients and prevent the development of severe complications.

Risk factors of metabolic syndrome among adult Sudanese sickle cell anemia patients

BACKGROUND

Sickle cell disease is a hereditary disorder characterized by haematological anaemia. Several studies assumed that adult sickle patients might develop metabolic syndrome features as hyperglycaemia, hypertension and dyslipidaemia. The aim of this study was to evaluate the metabolic syndrome risk factors among adult Sudanese with sickle cell anemia in the steady state.

METHODS

A prospective cross sectional study design was conducted among thirty adult patients with sickle cell anemia Hb SS (mean age 23 ± 6.1 years) and thirty healthy individuals matched for age and gender. Waist and hip circumferences were measured by simple tape. Venous blood sample were analysed to detect blood glucose level, uric acid, total cholesterol, triglycerides, low and high-density lipoprotein after 8 h overnight fasting by spectrophotometer. Blood pressure was measured by sphygmomanometer. National Cholesterol Education Program-Adult Treatment Panel III was utilised to define metabolic syndrome. Statistical analysis was performed SPSS software version 23. Continuous data were expressed using mean ± SD. P-value of < 0.05 (two-tailed) was used to establish statistical significance. Unpaired independent T- test was used.

RESULTS

No significant difference in mean systolic blood pressure in patients group compared to control (P value = 0.3). Mean value of diastolic blood pressure was significantly low in patients group compared to control (65.4 ± 10. 4 VS72.33 ± 8.27 mmHg, P value< 0.001). Fasting triglycerides level was comparable between patients group and control (P value = 0.56). While high-density lipoprotein was significantly lower in sicklers compared to control (30.2 ± 8.2 mg/dL vs 44.71 ± 1.85 mg/dL, P value< 0.001). Fasting blood glucose was significantly low in sickle compared to control (92.6 ± 13 mg/dL vs 106.83 ± 25.11 mg/dL P value< 0.001). Uric acid level was not statistically differed in patients group compared to control (p value = 0.5).

CONCLUSION

There was significant decrease in fasting High-density lipoprotein, diastolic blood pressure, mean arterial pressure and fasting blood glucose among SCA patients compared to control. There was no significant difference in waist circumference, systolic blood pressure, fasting triglycerides and uric acid levels between patients and control groups.

Neck circumference is independently associated with relative systemic hypertension in young adults with sickle cell anaemia

Background

A seemingly interesting observation in patients with sickle cell anaemia (SCA) is that they usually have lower systemic blood pressures (BP) and insulin resistance than persons in the general population in spite of chronic inflammation and vasculopathy. However, relative systemic hypertension (rHTN) has been linked to pulmonary hypertension, increased blood viscosity and renal insufficiency, which could indicate a risk of developing cardiometabolic disorder (CMD) in SCA.

We therefore hypothesized that neck circumference (NC) and CMD marker; triglyceride glucose (TyG) index would independently predict rHTN in young adults with SCA in steady state.

Methods

We compared the anthropometrical, hematological, hemorheological and CMD markers between SCA patients with normal BP < 120/70 mmHg; nHTN, n = 65) and those with rHTN (BP ≥ 120/70 mmHg, n = 32).

Results

Our results showed that SCA with rHTN had significantly higher body weight, waist circumference, NC, plasma viscosity, systolic and diastolic BP. Results also indicated that NC (OR: 2.98; 95% CI 1.46 to 6.10, p < 0.01) was a predictor of rHTN in SCA independent of gender, age, weight, waist circumference, BMI, blood viscosity, triglyceride or TyG. A receiver operating characteristic curve analysis also showed that NC was the most efficient predictor of rHTN than other CMD markers.

Conclusion

The present study demonstrates that increased NC is a salient risk factors that is independently associated with rHTN in SCA. The finding therefore underscores the utility of NC in early detection and stratification of systemic hypertension, particularly in individuals with SCA.

Rates and risk factors of hypertension in adolescents and adults with sickle cell anaemia in Tanzania: 10 years' experience

Data on the magnitude and risk factors for hypertension in sickle cell anaemia (SCA) are limited. A retrospective analysis of individuals with SCA aged ≥15 years enrolled from 2004-2014 at Muhimbili National Hospital, Tanzania was conducted to determine the prevalence, incidence and risk factors for hypertension. A total of 1013 individuals with SCA were analysed, of whom 571(56%) were females. The median age [interquartile range] was 17 [15-22] years. Four hundred and forty-one (44%) of the patients had relative hypertension [systolic blood pressure (SBP) 120-139 mmHg or diastolic blood pressure (DBP) 70-89 mmHg], and 79 (8%) had hypertension (SBP ≥ 140 mmHg or DBP ≥ 90 mmHg). The incidence of hypertension was 64/1000 person years of observation and the 5-year survival rate was 0·71 [95% confidence interval (CI): 0·67-0·75]. In multivariate analysis, age>18 years, Hazard ratio (HR) 1·50 (95% CI: 1·03-2·18); pulse pressure, HR 0·64 (95% CI: 0·42 to 0·98); pulse rate, 1·02 (95% CI: 1·01-1·03); body mass index (BMI), HR 1·08 (95% CI: 1·03-1·13); blood transfusion, HR 2·50 (95% CI: 1·01-6·21) and haemoglobin, HR 1·12 (95% CI: 1·05-1·33) were independently associated with hypertension. In conclusion, despite the younger age, hypertension in this population was higher than that reported in others studies. Age, BMI, pulse pressure and haemoglobin were independently associated with hypertension in SCA.

Genetics of Sickle Cell-Associated Cardiovascular Disease: An Expert Review with Lessons Learned in Africa

Sickle cell disease (SCD) vastly impacts the African continent and is associated with cardiovascular diseases. Stroke, kidney disease, and pulmonary hypertension are considered as proxies of severity in SCD with several genomic loci implicated in their heritability. The present expert review examined the current data on epidemiology and genetic risk factors of stroke, pulmonary hypertension, and kidney disease associated with SCD, as indexed in PubMed® and Google Scholar®. Studies collectively show that stroke and kidney disease each affect ∼10% of SCD patients, with pulmonary hypertension displaying a higher prevalence of 30% among adults with SCD. There is some evidence that these epidemiology figures may be an underestimate in SCD patients living in Africa. A modest number of publications have identified genetic factors involved in pathways regulating inflammation, coagulation, cell adhesion, heme degradation, α-globin and γ-globin production, and others, which contribute to the development risk of targeted cardiovascular phenotypes. However, in most cases, these studies have not been validated across populations. There is therefore an urgent need for large-scale genome-wide association, whole-exome and whole-genome studies, and multiomics research on cardiovascular diseases associated with SCD, particularly in Africa, to allow for proportional investment of global research funding on diseases that greatly impact the African continent. Ultimately, this will cultivate socially responsible research investments and identification of at-risk individuals with improved preventive medicine, which should be a cornerstone of global precision medicine.

Arterial Stiffness and Peripheral and Central Blood Pressure in Patients With Sickle Cell Disease

Blood pressure (BP) in patients with sickle cell disease (SCD) has been reported to be lower than in persons in the general population. Data on arterial stiffness, which is an important risk factor for the progression of BP, are inconclusive for this patient population. Forty-five adult patients with SCD and 40 controls matched for sex, age, and body mass index were studied. Brachial systolic BP (SBP) and diastolic BP (DBP) were significantly lower in the patient group (SBP 115.1±13.8 mm Hg vs 121.9±11.3 mm Hg and DBP 68.5±8.0 mm Hg vs 80.6±9.1 mm Hg, P<.05, respectively). Augmentation index (AIx), however, was significantly higher in SCD patients compared with healthy controls (24.9±9.6 for patients vs 12.4±10.8 for controls, P<.001), while carotid femoral pulse wave velocity was comparable between the two groups. The study shows that mechanisms other than arterial elasticity are involved in the low BP phenotype of patients with SCD.

Factors associated with growth and blood pressure patterns in children with sickle cell anemia: Silent Cerebral Infarct Multi-Center Clinical Trial cohort

Individuals with sickle cell anemia (SCA) exhibit delayed growth trajectories and lower blood pressure (BP) measurements than individuals without SCA. We evaluated factors associated with height, weight, and BP and established reference growth curves and BP tables using data from the Silent Cerebral Infarct Multi-Center Clinical (SIT) Trial (NCT00072761). Quantile regression models were used to determine the percentiles of growth and BP measurements. Multivariable quantile regression was used to test associations of baseline variables with height, weight, and BP measurements. Height and weight measurements were collected from a total of 949 participants with median age of 10.5 years [Interquartile range (IQR) 8.2-12.9] and median follow-up time of 3.2 years (IQR 1.8-4.7, range 0-12.9). Serial BP measurements were collected from a total of 944 and 943 participants, respectively, with median age of 10.6 years (IQR = 8.3-12.9 years), and median follow-up time of 3.3 years (IQR = 1.7-4.8). Multivariable quantile regression analysis revealed that higher hemoglobin measurements at baseline were associated with greater height (P < 0.001), weight (P = 0.000), systolic BP (P < 0.001), and diastolic BP (P = 0.003) measurements. We now provide new reference values for height, weight, and BP measurements that are now readily available for medical management.

Comparison of patients from Nigeria and the USA highlights modifiable risk factors for sickle cell anemia complications

To identify factors that affect manifestations of sickle cell anemia we compared patients 11-30 years of age from University of Ibadan, Ibadan, Oyo, Nigeria (n = 214) and University of Illinois at Chicago, Chicago, IL, USA (n = 209). Paralleling findings in the general populations of the two countries, the Chicago patients were more often overweight or obese as defined by the Centers for Disease Control and Prevention (Atlanta, GA, USA) guidelines, and more often had elevated blood pressure (BP) as defined by the National Heart, Lung, and Blood Institute (NHLBI), Bethesda, MD, USA guidelines. The Ibadan patients did not receive the pneumococcal vaccine or hydroxyurea (HU) therapy as frequently as the Chicago patients. Consistent with lower rates of elevated BP and increased body mass index (BMI), stroke history was less frequent in the Ibadan patients ≥18 years old. Furthermore, in combined analyses, systolic and diastolic BP directly correlated with BMI, and elevated weight status independently associated with history of stroke. Our findings are consistent with the possibility that higher values for BMI and BP in Chicago sickle cell anemia patients may contribute to an increased risk of stroke and highlights the need for measures to reduce these risk factors. On the other hand, lower pneumococcal vaccination and HU therapy rates in Ibadan patients highlights the need for more improved vaccination coverage and for studies to define the role of HU therapy in Africa.

Male gender, increased blood viscosity, body mass index and triglyceride levels are independently associated with systemic relative hypertension in sickle cell anemia

Patients with sickle cell anemia (SCA) have usually lower diastolic, systolic and mean blood pressure (BP) than the general population. However, BP values ≥120/70 mmHg considerably increase the risk for acute and chronic complications in SCA. The aim of this study was to identify biological factors associated with relative hypertension in adults with SCA. We compared the hematological, lipid and hemolytic profiles, as well as blood viscosity, between SCA patients with normal BP (<120/70 mmHg, n = 54) and those with relative hypertension (BP≥120/70 mmHg, n = 43). Our results demonstrated that male gender (OR: 3.49; 95%CI 1.20 to 10.16, p<0.05), triglycerides (OR: 9.19; 95% CI 2.29 to 36.95, p<0.01), blood viscosity (OR: 1.35; 95% CI 1.01 to 1.81, p<0.05) and body mass index (OR: 1.37; 95% CI 1.14 to 1.64, p<0.01) were independent risks factors for relative hypertension in SCA. No association was found between the BP status and the positive history of painful vaso-occlusive crisis or acute chest syndrome. An association between triglycerides level and the occurrence of these two major acute complications was detected. Our study suggests that male gender, increased triglycerides level, BMI and blood viscosity could increase the risk for developing relative hypertension in SCA. In addition, our results support a role of moderately elevated triglycerides in the pathophysiology of vaso-occlusive events.

Masked hypertension is prevalent in children with sickle cell disease: a Midwest Pediatric Nephrology Consortium study

BACKGROUND

The prevalence of hypertension and abnormal blood pressure (BP) patterns on 24-h ambulatory BP monitoring (ABPM) remains unknown in children with sickle cell disease (SCD).

METHODS

Thirty-eight asymptomatic children with sickle cell disease (SCD) (12 HbSS receiving routine care, 13 HbSC, and 13 HbSS receiving chronic transfusion therapy) underwent 24-h ABPM. Average clinic BP, demographic and biochemical characteristics were collected.

RESULTS

Median age was 13 years (range 11-16), body mass index (BMI) 19.1 kg/m(2) (range 18.2-21.1), and 50% were male. Seventeen subjects (43.6%) had ambulatory hypertension, while 4 (10.3%) were hypertensive based on their clinic BP. Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) dip were 8.3 ± 5.9% and 14.7 ± 7.6% respectively. Twenty-three subjects (59%) had impaired SBP dipping, 7 (18%) had impaired DBP dipping, and 5 (13%) had reversed dipping. Clinic and ABP classification were modestly correlated (rho = 0.38, P = 0.02).

CONCLUSION

Abnormalities in ABP measurements and patterns in children with SCD are prevalent and require more attention from heath care providers. ABPM is a valuable tool in identifying masked hypertension and abnormalities in circadian BP.