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Haematological values in steady-state sickle cell anaemia patients and matched heamoglobin AA Controls in a Rural Area of Eastern Gabon

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Abstract

Background: In Gabon, universal neonatal screening of sickle cell disease is not carried out in rural areas, often leading to late detection of the disease. However, complete blood counts are available in rural areas. Materials and methods: We evaluated the haematological parameters of 45 homozygous steady-state sickle cell anaemia (SCA) patients and compared them with 45 sex- and age-matched Haemoglobin AA controls in Koula-Moutou, a rural area in Eastern Gabon. Results: Homozygous SCA patients had low erythrocyte values (red blood cells: 2.50 × 1012/L, haemoglobin: 7.20 g/dL and haematocrit: 20.70%) and high leucocyte values (white blood cells: 14.40 × 109/L, lymphocytes: 5.24 × 109/L and monocytes: 1.60 × 109/L). Most of the SCA patients had severe anaemia (67%), normochromia (76%), lymphocytosis (73%) and monocytosis (84%). A haemoglobin level of < 8.5 g/dL together with a leucocyte level above 9.5 × 109 cells/L was used as screening test to detect homozygous SCA patients, with sensitivity of 84.4% and specificity of 97.8%. Conclusion: The values for erythrocyte and leucocyte cell lines of SCA patients in steady state are clearly different from those of the matched HbA/A controls. This makes it possible to set up a tool to detect SCA based on the haemogram in a rural area that does not possess haemoglobin electrophoresis. This tool could be used by healthcare workers in the absence of universal newborn screening for SCA.
© 2019 Nigerian Postgraduate Medical Journal | Published by Wolters Kluwer - Medknow 13
Original Article
IntroductIon
Sickle cell anaemia (SCA) is an inherited autosomale recessive
disease, which manifests as chronic haemolytic anaemia,
painful episodes of vaso-occlusive crisis and polysystemic
organic damage.[1] In Gabon, neonatal screening for sickle cell
disease (SCD) is not universal despite the launch of a national
program to curb the disease in 2007. Neonatal screening of
4,068 newborns detected 1.33% HbS/S and 0.14% HbS/C SCD
in urban areas in Libreville.[2] However, neonatal screening
is unavailable in rural areas, and sickle cell patients are thus
screened later in life during medical consultation.
SCD includes a set of quantitative and qualitative changes
inside and outside the blood vessels that are responsible for
the destruction of red blood cells (RBCs).[1] In sub-Saharan
African SCD patients, severe anaemia is associated with
clinical complications such as leg ulcers, microalbuminuria
or pulmonary hypertension.[3]
Although SCD pathology is mainly due to RBCs, white blood
cells (WBCs) also participate in obstructing blood vessels, a
central phenomenon of vaso-occlusive crises in SCD.[1] The
haematological parameters in a complete blood count (CBC),
which determines WBC abnormalities, may be a useful tool to
assess SCD severity. For instance, a high number of medical
emergencies due to SCD are associated with leucocytosis.[4]
In many studies, a decrease in haematological parameters such
as RBC count and haemoglobin and an increase in WBCs
and platelets are associated with an increase in the number
of vaso-occlusive crises in homozygous SCD patients.[4,5] In
Haematological Values in Steady-State Sickle Cell Anaemia
Patients and Matched Heamoglobin AA Controls in a Rural Area
of Eastern Gabon
Landry Erik Mombo1, Gaël Mabioko-Mbembo1,2, Cyrille Bisseye1, Kevin Mbacky2, Fatoumata Thiam2, Apollinaire Edou2
1Laboratory of Molecular and Cellular Biology (LABMC), University of Science and Technology of Masuku (USTM), Franceville, 2Paul Moukambi Regional Hospital
Centre of Koula‑Moutou (CHRPM), Koula‑Moutou, Gabon
Background: In Gabon, universal neonatal screening of sickle cell disease is not carried out in rural areas, often leading to late detection of the
disease. However, complete blood counts are available in rural areas. Materials and Methods: We evaluated the haematological parameters
of 45 homozygous steady-state sickle cell anaemia (SCA) patients and compared them with 45 sex- and age-matched Haemoglobin AA
controls in Koula-Moutou, a rural area in Eastern Gabon. Results: Homozygous SCA patients had low erythrocyte values (red blood cells:
2.50 × 1012/L, haemoglobin: 7.20 g/dL and haematocrit: 20.70%) and high leucocyte values (white blood cells: 14.40 × 109/L, lymphocytes:
5.24 × 109/L and monocytes: 1.60 × 109/L). Most of the SCA patients had severe anaemia (67%), normochromia (76%), lymphocytosis (73%)
and monocytosis (84%). A haemoglobin level of < 8.5 g/dL together with a leucocyte level above 9.5 × 109 cells/L was used as screening test
to detect homozygous SCA patients, with sensitivity of 84.4% and specicity of 97.8%. Conclusion: The values for erythrocyte and leucocyte
cell lines of SCA patients in steady state are clearly different from those of the matched HbA/A controls. This makes it possible to set up a
tool to detect SCA based on the haemogram in a rural area that does not possess haemoglobin electrophoresis. This tool could be used by
healthcare workers in the absence of universal newborn screening for SCA.
Keywords: Gabon, red blood cell, rural areas, sickle cell anaemia, white blood cell
Address for correspondence: Dr. Landry Erik Mombo,
Laboratory of Molecular and Cellular Biology (LABMC), University of
Science and Technology of Masuku (USTM), BP 943, Franceville, Gabon.
E‑mail: lemombo.ustm@gmail.com
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How to cite this article: Mombo LE, Mabioko-Mbembo G, Bisseye C,
Mbacky K, Thiam F, Edou A. Haematological values in steady-state sickle
cell anaemia patients and matched heamoglobin AA controls in a rural area
of Eastern Gabon. Nigerian Postgrad Med J 2019;26:13-7.
Abstract
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Mombo, et al.: Haematological values in SCA patients in Gabon
Nigerian Postgraduate Medical Journal ¦ Volume 26 ¦ Issue 1 ¦ January-March 2019
14
addition, haematological values are reported to differ between
patients with HbS/S or HbS/β-thal and those with HbS/C.[3,6,7]
Haematologic parameters can also be used in collaboration with
other parameters to evaluate the efcacy of hydroxycarbamide
therapy, as shown by a study from Italy where improvement in
haemoglobin, haematocrit, mean corpuscular volume (MCV),
platelets and WBCs counts was observed among SCD patients
on hydroxycarbamide.[8]
Although haematological parameters in SCD patients and
control groups have been examined in previous studies,[5,7]
few studies have compared sickle cell patients to sex- and
age-matched control populations in Africa.[9] The aim of
our study was to compare the haematological parameters of
homozygous SCA patients and sex- and age-matched HbA/A
controls in order to test whether CBC results are a useful guide
for medical staff in a rural area of Gabon to refer patients for
haemoglobin electrophoresis.
MaterIals and Methods
Ninety participants who presented at Paul Moukambi Regional
Hospital Centre (CHRPM) for a routine medical consultation
between July and December 2015 were included in the
study. The study population was 44 females and 46 males,
aged 1–26 years with an average age of 10 years. Of the 90
participants, 45 were SCA patients and 45 were sex- and
age-matched controls. All SCA patients were in steady state
with HbS/S conrmed by haemoglobin electrophoresis. None
of the SCA patients was on hydroxycarbamide therapy. All
sex- and age-matched controls were apparently healthy with
HbA/A conrmed by haemoglobin electrophoresis.
The separation of the normal haemoglobins (A and A2) and the
detection of the major haemoglobin variants (S or D and C or
E) were performed by qualitative electrophoresis on alkaline
agarose gels (pH 8.5) using Hydragel 15 Haemoglobin(e)
kits (a semi-automated Hydrasys system from SEBIA– Paris,
France) and following the manufacturer’s instructions.
CBCs were made using venous blood samples collected
in an ethylenediaminetetraacetic acid bottle and analysed
within 24 h of collection using an automated haematology
analyser (Mindray BC 3000 plus, Mindray Bio-Medical
Electronics Co., Ltd, Shenzhen, People’s Republic of China)
following the manufacturer’s instructions.
Our study was approved by the Institutional Ethics Committee
of Paul Moukambi Regional Hospital Centre (CHRPM) in
June 2015 in Koula-Moutou (Gabon). Adults and parents or
guardians of children gave their written informed consent
before being included in the study.
Statistical analysis was performed using (SPSS, IBM corp.,
New York, NY, USA). The median values of haematological
parameters were compared between SCA and matched
controls using Wilcoxon and Kruskal–Wallis rank sum
tests. The difference was considered significant where
P < 0.05.
results
Red blood cell values in steady-state sickle cell anaemia
patients and matched controls from rural areas
RBC count, haematocrit and haemoglobin levels were
significantly lower in homozygous SCA patients than in
matched controls and signicantly higher for mean corpuscular
haemoglobin (MCH) and MCH concentration values
[Table 1]. In the erythrocyte parameters, only MCV showed
no significant difference between homozygous SCA and
matched controls (P = 0.778). Severe or moderate anaemia
was signicantly more likely to be present in SCA patients
than in matched controls [Table 2] (96% vs. 35%, P < 0.001).
The prevalence of microcytic anaemia was not signicantly
different between homozygous SCA patients (29%) and
matched controls (26%) (P = 0.815). Hypochromia was
significantly more prevalent in controls (69%) while
normochromia (76%) was higher in homozygous SCA
patients (P < 0.0001).
Other blood cell values in steady-state sickle cell anaemia
patients and matched controls from rural areas
The median WBC counts (lymphocyte, monocyte and
granulocyte) were twice as high in SCA patients as in matched
controls (P < 0.001) [Table 1]. Lymphocytosis was present
in 73% of homozygous SCA patients but was observed in
only 22% of controls (P < 0.001). Similarly, monocytosis
and granulocytosis were significantly more prevalent in
homozygous SCA patients than in matched controls (84% vs.
33%, P < 0.001; 51% vs. 11%, P < 0.001).
Median platelet count was signicantly higher in homozygous
SCA patients than in matched controls (P = 0.035), [Table 1].
However, the prevalence of abnormalities of the platelet
lineage (thrombocytopenia and thrombocytosis) was not
significantly different in homozygous SCA patients and
matched controls (P = 0.258), [Table 2].
Haemogram method for sickle cell disease detection
The haemogram method tested in our study consists of the
diagnosis of SCA through a threshold alert if haemoglobin
is <8.5 g/dL and leucocyte is >9.5 × 109/L. As shown in Table 3,
the sensitivity, specicity and positive predictive values of this
method were 84.4%, 97.8% and 97.4%, respectively.
dIscussIon
We evaluated the haematological parameters of steady-state
homozygous SCA patients and controls matched by age and
sex living in rural areas in eastern Gabon to determine a set
of indices to screen for SCA.
Red blood cells in steady-state sickle cell anaemia
patients and matched controls from rural areas
The haemolysis that occurs in homozygous SCA patients
accounts for the reduction of the erythrocyte count found in
this study, such as RBC (2.50 × 1012 cells/L), haemoglobin
(7.20 g/dL) and haematocrit (20.70%). The erythrocyte values
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Mombo, et al.: Haematological values in SCA patients in Gabon
Nigerian Postgraduate Medical Journal ¦ Volume 26 ¦ Issue 1 ¦ January-March 2019 15
obtained in this study are lower than those observed in Nigerian
and African-American homozygous SCA populations.[5,7] This
difference is also found when we compare the haemoglobin
levels of Gabonese control populations with those of the
Nigerian and African-American control populations.[5,7] This
reduction in haemoglobin levels in both SCA and controls
Table 1: Mean and median values of haematological parameters in steady-state sickle cell anaemia patients and
matched controls living in rural areas (Koula-Moutou)
Parameters SCA patients (n=45) Matched controls (n=45) Wilcoxon test
P
Mean±SD Median Mean±SD Median
RBC, 1012/L 2.54±0.759 2.50 4.37±0.673 4.46 <0.001
Hb, g/dL 7.08±1.727 7.20 11.26±2.170 11.10 <0.001
Haematocrit, % 29.99±5.583 20.70 36.44±7.082 36.10 <0.001
MCV,  84.87±11.476 84.00 83.37±8.948 84.40 0.778
MCHC, g/dL 33.18±2.394 33.10 30.90±2.478 30.40 <0.001
MCH, pg 28.61±4.515 28.00 25.82±2.971 25.90 0.002
WBC, 109/L 15.64±7.016 14.40 7.78±3.004 6.90 <0.001
Lymphocytes, 109/L 5.93±3.099 5.24 2.93±1.494 2.55 <0.001
Monocytes, 109/L 1.79±1.215 1.60 0.87±0.513 0.68 <0.001
Granulocytes, 109/L 7.92±4.854 7.51 3.98±2.277 3.34 <0.001
Platelets, 109/L 368.53±192.474 368.00 290.39±141.564 247.00 0.035
SD: Standard deviation, RBC: Red blood cell, MCV: Mean corpuscular volume, MCHC: Mean corpuscular haemoglobin concentration, MCH: Mean
corpuscular haemoglobin, WBC: White blood cell, SCA: Sickle cell anaemia, Hb: Haemoglobin
Table 2: Distribution of blood cell anomalies in steady-state sickle cell anaemia patients and matched controls living in
rural areas (Koula-Moutou)
Blood cell anomalies SCA patients, n (%) Controls, n (%) P (Kruskal-Wallis test)
Anaemia forms
No anaemia or light (1) 2 (4) 29 (65) <0.001
Moderate (1) 13 (29) 14 (31)
Severe (1) 30 (67) 2 (4)
MCV
Microcytosis (2) 13 (29) 11 (25) 0.815
Normocytosis 27 (60) 33 (73)
Macrocytosis (>98 ) 5 (11) 1 (2)
MCHC
Hypochromic (<32%) 11 (24) 31 (69) <0.001
Normochromic 34 (76) 14 (31)
Granulocyte
Granulocytopenia (<1.5 109/L) 0 (0) 4 (9) <0.001
Normal 22 (49) 36 (80)
Granulocytosis (>7 109/L) 23 (51) 5 (11)
Lymphocyte
Lymphocytopenia (<1.5 109/L) 1 (2) 6 (14) <0.001
Normal 11 (25) 29 (64)
Lymphocytosis (>4 109/L) 33 (73) 10 (22)
Monocyte
Normal 7 (16) 30 (67) <0.001
Monocytosis (>0.8 109/L) 38 (84) 15 (33)
Platelets
Thrombocytopenia (<150 109/L) 7 (16) 5 (11) 0.258
Normal 19 (42) 29 (64)
Thrombocytosis (>400 109/L) 19 (42) 11 (25)
(1) Anaemia was diagnosed according to WHO criteria by age and sex; Children under 5 years: No anaemia Hb [11- + ∞], mild Hb [10-10.9], moderate
Hb [7-9.9] and severe Hb [0-6.9]; Children 5-11 years: No anaemia Hb [11.5- + ∞], mild Hb [11-11.4], moderate Hb [8-10.9] and severe Hb [0-7.9];
Children 12-14 years and non-pregnant women: No anaemia Hb [12- + ∞], mild Hb [11-11.9], moderate Hb [8-10.9] and severe Hb [0-7.9]; Men
over 14 years: No anaemia Hb [13- + ∞], mild Hb [11-12.9], moderate Hb [8-10.9] and severe Hb [0-7.9]. (2) Microcytosis according to WHO standards is
diagnosed when MCV is lower: At 70  under 2 years, at 73  for 2-6 years, at 80  for 6-14 years and at 82  beyond 14 years. MCV: Mean corpuscular
volume, MCHC: Mean corpuscular haemoglobin concentration, SCA: Sickle cell anaemia, Hb: Haemoglobin
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Mombo, et al.: Haematological values in SCA patients in Gabon
Nigerian Postgraduate Medical Journal ¦ Volume 26 ¦ Issue 1 ¦ January-March 2019
16
could be due to nutritional deciency and high prevalence of
infectious diseases in rural areas.
Several studies have shown that erythrocyte counts vary
across HbS/C, HbS/β-thal and HbS/S SCD genotypes, with
lowest values for the latter.[3,6,7] All sickle cell patients in our
study were of HbS/S genotype, which may explain their lower
erythrocyte values. However, the haemoglobin level for HbS/S
cases (7.20 g/dL) is lower than that of sickle cell patients
with the same genotype in the USA (Hb = 8.6 g/dL) and in
Nigeria (Hb = 7.54 g/dL).[5,7] This could be explained by the
absence of α-thalassemia among SCA patients in our study. The
absence of α-thalassemia leads to a reduction in erythrocyte
haematological values, for example, the haemoglobin level
falls from 8.92 to 7.98 g/dL.[6] However, an earlier study of
heterozygous SCA patients in Gabon showed a high frequency
of α-thalassemic traits determined indirectly, and another
study in neighbouring Cameroon showed co-inheritance of
the α-thalassemic variant in homozygous and heterozygous
sickle cell patients.[10,11] This suggests the probable presence
of α-thalassemic variant in our homozygous SCA patients.
Nevertheless, the erythrocyte values are low, supporting the
hypothesis that nutritional deciencies and infection pressure
are greater problems in rural Gabon than in the USA and
Nigeria.
A study conducted at Monkole Hospital Centre in
Kinshasa (Democratic Republic of Congo) with 42 sickle
cell patients of the Bantu ethnic group in conditions similar
to those in our study, found haematological values similar
to ours in homozygous SCA patients except for MCV and
platelet counts.[12] In our study, abnormalities of the blood
count, such as microcytosis, macrocytosis, thrombocytopenia
and thrombocytosis, did not differ in prevalence between
homozygous SCA and matched controls. The difference
observed between the two studies may be due to the use of
matched controls for sex and age in our study and of unmatched
controls in the Tshilolo et al.’s study[12] because haemogram
values depend on these 2 factors.
Other blood cell counts in steady-state sickle cell anaemia
patients and matched controls from rural areas
Because of SCA and underlying bacterial infections, leucocyte
counts were higher in homozygous sickle cell patients than
in controls, with 14.40 × 109/L for WBCs; 5.24 × 109/L for
lymphocytes; 1.60 × 109/L for monocytes and 7.51 × 109/L
for granulocytes. However, leucocyte values in homozygous
SCA patients in rural areas were still very high compared with
leucocyte counts of 12.72 × 109/L observed in homozygous
sickle cell patients in urban areas in Nigeria.[5] This may be
explained by a high prevalence of infectious disease in rural
areas.
The leucocytosis observed in homozygous SCA patients
in our study affects all types of WBCs (lymphocytosis,
monocytosis and granulocytosis). This was not the case for
leucocytosis found in African-American homozygous sickle
cell patients where the lymphocyte was normal.[7] The 2-fold
higher monocyte counts and monocytosis observed in sickle
cell patients can be explained by monocyte activation in these
individuals. Indeed, a recent study suggests that haem-linked
iron, which is released during intravascular haemolysis in
sickle cell patients, contributes to the inflammation and
activation of monocytes through toll-like receptors signalling
increment.[13]
Although the median platelet count was higher in homozygous
SCA patients than in controls in our study, there was no
association between thrombocytosis and steady-state SCA.
The precise role of platelets in thrombocytosis, inammation
and haemolysis is only partially understood.[14] Nevertheless,
circulating platelets in patients with sickle cell crisis can
stimulate endothelial cell activation. This stimulation is
performed by direct contact or even adhesion of platelets to
endothelial cells and through the NF-kB-dependent signalling
pathway, thus contributing to the vaso-occlusive process.[15]
Thrombocytosis was not associated with steady-state SCA
in our study, although it is associated with acute sickle cell
crisis.[16] A very high platelet count that is synonymous
with thrombocytosis suggests the additional inammatory
mechanism in which platelets of sickle cell patients secrete
signicant amounts of cytokines and many cytokine messenger
RNAs.[17] This second mechanism, which affects vasculopathy
during SCA, is rare in steady-state sickle cell patients because
of the lower level of platelets in this phase.
Haemogram method for sickle cell anaemia detection
The diagnosis of SCD in African populations is generally
late at a mean age of 7 years.[18] The haemogram could be
a useful tool in the diagnosis of SCA, particularly in rural
Table 3: Comparison of haemogram method and haemoglobin electrophoresis in the detection of sickle cell anaemia
Haemogram
method
Haemoglobin electrophoresis
SCA patients Healthy patients
Reactive 38 1Positive predictive value (95% CI)
97.4% (84.9-99.9)
Non-reactive 7 44 Negative predictive value (95% CI)
86.3% (73.1-3.8)
Sensitivity (95% CI)
84.4% (69.9-93.0)
Specicity (95% CI)
97.8% (86.6-99.9)
SCA: Sickle cell anaemia, CI: Condence interval
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Mombo, et al.: Haematological values in SCA patients in Gabon
Nigerian Postgraduate Medical Journal ¦ Volume 26 ¦ Issue 1 ¦ January-March 2019 17
areas, through a threshold alert if haemoglobin <8.5 g/dL and
leucocyte >9.5 × 109/L. Using this method, 84.4% of SCA
patients would have been referred for SCA diagnosis during our
study. Moreover, for future studies, a positive predictive value of
97.4% may constitute a good indicator for SCD electrophoresis
screening of patients. With a specicity of 97.8%, this method
avoids the selection of individuals with solely uncomplicated
Plasmodium falciparum malaria in Sub-Saharan Africa, which
present mean haemoglobin of 8.9 g/dL and mean leucocyte
count of 8.8 × 109/L.[19] The haemoglobin threshold of 8.5 g/dL
proposed in this study corresponds to the threshold observed
in 504 sickle cell children starting hydroxycarbamide therapy
in a study conducted in Italy.[8] However, this haemogram
method is only useful to refer presumed sickle cell patients
with haemoglobin HbS/S.
The main limitation of our study (red or WBC counts and
haemogram method of detection of SCA) was the small sample
size. To be denitively adopted, the proposed haemogram method
should be evaluated in a larger population and for a longer period.
conclusIon
In our study in rural Gabon, steady-state homozygous SCA
patients had very low erythrocyte values, whereas they had a
very high number of leucocytes. These SCA patients mainly
presented severe anaemia, normochromia, lymphocytosis
and monocytosis. Haemoglobin levels <8.5 g/dL and
leucocytes >9.5 × 109/L could be used to trigger SCA screening
in rural Gabon. This tool could be used in the absence of
neonatal SCD screening in poorly served areas.
Acknowledgements
The authors thank Mr. Lionel Kevin Makosso and
Mr. Stephane Meyet Me Bie (USTM, Franceville, and
CHRPM, Koula-Moutou, Gabon), and all technicians of
Medical Analysis Laboratory (CHRPM, Koula-Moutou,
Gabon) for technical help, Pr. Joanna M. Setchell (Durham
University, Durham, UK) for critically reading the manuscript
and Pr. Jacques Elion (National Blood Transfusion Institute,
Paris, France) for general support.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conicts of interest.
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... Left ventricular hypertrophy has been evaluated extensively globally in clinical settings and to a less extent, in the general 2,9,10 population. However, in Africa and especially West Africa, population-based studies with a view of the gender peculiarities of electrocardiographic LVH are generally 5,[11][12][13] lacking. ...
... The mean age at diagnosis in the current study is comparable to that of 12 Oguntola and his colleagues in south western Nigeria who found a mean age of 25.8 years. It is also similar to the report of 25.0 ± 12.8 years 13 by Ahmed et al in Zaria North Western Nigeria. The increase of appendicitis during the third decade of life may be attributed to the increased lymphoproliferative activity resulting in lymphoid hyperplasia in the 14 appendix at this age group. ...
... Steady-state TLC in SCD has been shown by 10-various investigators to be relatively high. 13 This steady-state leucocytosis is thought to be due to the influence of elevated acute phase proteins on bone marrow production of leucocytes. It is postulated that the steady-state of SCD is characterized by minimal levels of vaso-occlusion that may result in increased amounts of acute phase proteins and cytokine mediators with subsequent increased 14 production of leucocytes. ...
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Background: Nigeria has the highest burden of sickle cell disease (SCD) in the world, yet the vast majority of its patients do not have access to evidence-based cure. Haematological parameters in steady-state remain useful as indicators for initiating treatment and monitoring response to therapy as well as for prognostication. Objectives:This study aimed to determine the steady- state haematological parameters of children with SCD at a reference hospital in North-eastern Nigeria. Methods: A prospective observational study of children with steady state sickle cell disease, and aged 2 years – 16 years, was conducted from January, 2019 – October, 2020. The following haematological indices were obtained from participants; total leucocyte count, platelet count, haematocrit and haemoglobin concentration. Analysis of data was done with the statistical package for social sciences (SPSS) version 20.0. Results: One hundred patients were recruited. The mean age was 6.97 ± 3.63 years, with 61(61%) males and 39(39%) females giving a male: female ratio of 1.6:1. Mean total leucocyte count, mean platelet count, mean haemoglobin concentration and mean haematocrit were16.83±7.30 x 109/L, 356.66±178.27x109/L, 7.65±1.45g/dL and 23.51±3.90% respectively. Males had a significantly higher mean platelet count than females (P= 0.02). However, gender-based differences in the other haematological parameters were not statistically significant. Conclusion: The present study found raised levels of total leucocyte counts and platelet counts but low haematocrit and haemoglobin concentrations in children with steady- state SCD. These findings would be helpful in the management of paediatric SCD in this part of Nigeria. KEYWORDS: Sickle cell disease; Total leucocyte count; Platelet count; Haematocrit; Haemoglobin concentration.
... This is in agreement with previous studies, which also reported significantly higher WBC count in patients with HbSS even in a steady state. 10,21 White blood cell count contributes to the pathogenesis of SCA by adhering to blood vessel walls and stimulating the vascular endothelial cells to increase its expression of ligands for adhesion molecules on blood cells with consequent obstruction of the lumen of a blood vessel, causing tissue damage and inflammatory reaction. This may explain the finding of this study, where WBC count was found to have a positive correlation with CRP level, though not significant. ...
... Previous studies have also reported significantly lower haemoglobin levels among patients with HbSS compared to those with HbAA and HbAS. 10,21 There was also a negative correlation between CRP and haemoglobin levels, though not significant. Huang et al., 23 also reported an inverse relationship between CRP and haemoglobin levels. ...
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BACKGROUND Sickle cell anaemia (SCA) is a genetic disorder of haemoglobin and chronic inflammatory state. This study aimed to determine and compare C-reactive protein (CRP) levels and blood counts in participants with SCA (HbSS) and control (HbAS and HbAA). MATERIALS AND METHODS A cross-sectional comparative study was carried out among steady-state HbSS individuals with age-and sex-matched control from August 2019 to February 2020. Using the method described by Charan and Biswas and sickle cell disease prevalence of 3.5%, a sample size of 47 was calculated. However, 101 participants were recruited using a consecutive sampling technique. An assay of haemoglobin phenotype, CRP level and some haematological parameters, including haemoglobin level, white blood cell count and platelet count, were done. Data analysis was done using SPSS software, version 26. RESULTS One hundred and one subjects participated in the study and were made up of 51 (50.5%) males and 50 (49.5%) females with an age range of 1 to 52 years. They comprised 58 HbSS and 43 controls (23 HbAS and 20 HbAA). There was a significant increase in CRP level among HbSS participants (5.4µg/ml ±4.5) compared to those of HbAS (0.02µg/ml ± 0.01) and HbAA (0.02µg/ml ± 0.01) (p = 0.000). Correlation between CRP level and blood counts showed weak positive relationship between CRP and WBC count (r = 0.285, P = 0.07) as well as platelet count (r = 0.156, P = 0.336) but negative correlation between CRP and haemoglobin level (r =-0.073, P = 0.655). CONCLUSION There was a significantly higher CRP level among patients with HbSS in a steady state compared to control (HbAS and HbAA individuals).
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Introduction: Sickle cell anemia is characterized by chronic red cell hemolysis which leads to chronic anemia. Patients with sickle cell may be asymptomatic (steady-state) even with anemia. One easy and minimally invasive method of assessing anemia is by using the packed cell volume. Objective: The study aimed at determining the steady-state packed cell volume among sickle cell patients and to ascertain if Doppler ultrasound can be used to predict the degree of anemia in sickle cell disease. Methods: Fifty males and 50 females aged 0-30years with homozygous sickle cell genotype were recruited in this cross-sectional study. Their packed cell volume and Doppler ultrasound parameters (peak systolic velocity, end-diastolic velocity, pulsatility index, resistivity index and systolic-diastolic ratio) were measured and correlated using SPSS version 22. Results: The steady-state mean packed cell volume were 23.54% and 24.92% for the females and males respectively. There was no correlation between packed cell volume and Doppler parameters. Conclusion: The steady-state packed cell volume was lower in patients with sickle cell anemia than the expected values for the general population. Doppler ultrasound could not be used to predict the degree of anemia in sickle cell patients.
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Sickle cell disease (SCD) is a group of inherited disorders caused by mutations in HBB, which encodes haemoglobin subunit β. The incidence is estimated to be between 300,000 and 400,000 neonates globally each year, the majority in sub-Saharan Africa. Haemoglobin molecules that include mutant sickle β-globin subunits can polymerize; erythrocytes that contain mostly haemoglobin polymers assume a sickled form and are prone to haemolysis. Other pathophysiological mechanisms that contribute to the SCD phenotype are vaso-occlusion and activation of the immune system. SCD is characterized by a remarkable phenotypic complexity. Common acute complications are acute pain events, acute chest syndrome and stroke; chronic complications (including chronic kidney disease) can damage all organs. Hydroxycarbamide, blood transfusions and haematopoietic stem cell transplantation can reduce the severity of the disease. Early diagnosis is crucial to improve survival, and universal newborn screening programmes have been implemented in some countries but are challenging in low-income, high-burden settings. Full-text access to a view-only version is available by using the following SharedIt link: http://rdcu.be/I6qn
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The hyperhemolysis paradigm that describes overlapping "hyperhemolytic-endothelial dysfunction" and "high hemoglobin-hyperviscous" subphenotypes of sickle cell disease (SCD) patients is based on North American studies. We performed a transversal study nested in the CADRE cohort to analyze the association between steady-state hemolysis and vascular complications of SCD among sub-Saharan African patients. In Mali, Cameroon, and Ivory Coast, 2407 SCD patients (1751 SS or sickle β-zero-thalassemia [Sβ0], 495 SC, and 161 sickle β+-thalassemia [Sβ+]), aged 3 years old and over, were included at steady state. Relative hemolytic intensity was estimated from a composite index derived from principal component analysis, which included bilirubin levels or clinical icterus, and lactate dehydrogenase levels. We assessed vascular complications (elevated tricuspid regurgitant jet velocity [TRV], microalbuminuria, leg ulcers, priapism, stroke, and osteonecrosis) by clinical examination, laboratory tests, and echocardiography. After adjustment for age, sex, country, and SCD phenotype, a low hemoglobin level was significantly associated with TRV and microalbuminuria in the whole population and with leg ulcers in SS-Sβ0 adults. A high hemolysis index was associated with microalbuminuria in the whole population and with elevated TRV, microalbuminuria, and leg ulcers in SS-Sβ0 adults, but these associations were no longer significant after adjustment for hemoglobin level. In conclusion, severe anemia at steady state in SCD patients living in West and Central Africa is associated with elevated TRV, microalbuminuria, and leg ulcers, but these vascular complications are not independently associated with indirect markers of increased hemolysis. Other mechanisms leading to anemia, including malnutrition and infectious diseases, may also play a role in the development of SCD vasculopathy.
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A central role of inflammation in the pathophysiology of sickle cell disease (SCD) is supported by clinical observations. Both an elevated leucocyte count and C‐reactive protein (CRP) are associated with early death in SCD (Platt et al, 1994; van Beers et al, 2015). We have shown that iron‐regulated gene expression is associated with striking upregulation of inflammasome pathway gene expression, including a 200‐fold increase in Toll‐like receptor 4 (TLR4) expression in peripheral blood mononuclear cells, suggesting a cross‐talk between iron and inflammation pathways (van Beers et al, 2015). Haem, a form of iron, augments pro‐inflammatory TLR4 signalling in sickle cell mice, with subsequent inflammation, vaso‐occlusion, organ damage and death (Ghosh et al, 2013; Belcher et al, 2014; Vinchi et al, 2016). TLR4 is highly expressed on macrophages and peripheral blood monocytes, and its ligand, lipopolysaccharide (LPS), induces expression of the pro‐inflammatory cytokine interleukin 6 (IL6). We hypothesized that intracellular iron is involved in this LPS induction of IL6.
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Background: Infant mortality due to sickle cell disease in sub-Saharan Africa is high, necessitating a better understanding of the modulating factors of the disease in this region. Methods: We assessed the hereditary persistence of foetal haemoglobin and α-thalassemia. We diagnosed 787 subjects, with or without sickle cell trait, by capillary electrophoresis in the Medical Diagnostic Laboratory of the CIRMF (Franceville, Gabon). Results: Heterocellular and pancellular forms of hereditary persistence of foetal haemoglobin occurred at low rates of 10.9 and 2.3%, respectively. The distribution of HbS levels in individuals with sickle cell trait was trimodal, showing a high percentage (52.4%) of heterozygous subjects with α-thalassemia. The distribution of HbA2 levels was bimodal in individuals without sickle cell trait, estimated to be comprised of 12 and 15% of α and β-thalassemic heterozygous subjects, respectively. Conclusions: In sub-Saharan Africa, α-thalassemia is a far more prevalent modulating factor than hereditary persistence of foetal haemoglobin. Our study highlights the need for further investigation of thalassemia, haemoglobinopathies that are neglected in sub-Saharan Africa.
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Background. An exponential increase in the number of sickle cell disease (SCD) patients in paediatric services in Cape Town, South Africa, has been reported. The trend in adult/adolescent services has not been investigated. Objectives. To evaluate epidemiological trends of SCD and the profile of patients affected by SCD attending the Haematology Clinic at Groote Schuur Hospital (GSH), Cape Town. Methods. (i) A retrospective review of the number of SCD patients over the past 20 years; (ii) a cross-sectional analysis of clinical and haematological characteristics of SCD patients; and (iii) molecular analysis of the haemoglobin S mutation, the haplotype in the β-globin-like genes cluster, the 3.7 kb α-thalassaemia gene deletion and 19 selected single-nucleotide polymorphisms (SNPs) associated with fetal haemoglobin (HbF) levels. Results. From 1995 to 2016, 81 adolescent/adult patients with SCD were registered, mostly originating from other African countries (n=61, 75.3%). There was an increase of over 200% in new cases (n=47) during the last quarter of the two decades investigated. Data from 34 of 58 regular attendees (58.6%) were analysed. The mean age of the patients was 26.1 years (standard deviation (SD) 9.8), and 70.6% were male. With the exception of four patients with sickle/β-thalassaemia, all the patients had SCD (haemoglobin SS). The co-inheritance of a single 3.7 kb α-globin deletion was found in 42.3% of cases (n=11). The Bantu haplotype was the most observed (65.4% of chromosomes). Most HbF-promoting SNPs were not associated with variable levels of haematological indices. Conclusions. There is an increasing burden of adult SCD patients at GSH. National health and academic institutions need to adapt policies and healthcare professional training accordingly.
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Sickle cell anemia has many sequelae that result in emergency department (ED) use, but a minority of patients with sickle cell disease are frequent utilizers and make up the majority of ED visits. If patients who are likely to be frequent ED can be identified in steady state, they can be treated with disease modifying agents in an attempt to reduce ED use frequency. We sought to identify steady state markers for frequent ED use. We identified all patients with SS/Sβ0 seen at our facilities in 2012. Health care utilization over the entire year was calculated and ED visit numbers categorized as either 0-1, 2-5, or 6 or more visits a year. Steady state and acutely active laboratory parameters were collected and analyzed using analysis of variance models and odds ratios. 432 adult sickle cell patients were identified, ages 18-87, 54% female, and 38% had been prescribed hydroxyurea. Of the 432 patients,192 had 0-1 visits in the year, 144 had 2-5 visits in the year, and 96 had >6 visits for a total of 2259 visits. Those who had >6 visits accounted for 1750 (77%) of the total visits for the year. When steady state laboratory markers were examined, each additional 50x109/L platelets was associated with 22% greater risk (p < .001); each 1x109/L of WBC was associated with 11% greater risk (p = .003), and each 1g/dL Hb was associated with 23% lower risk (p = .007) of >6 ED visits/year. We did not observe a relationship between baseline HbF, LDH or reticulocyte count with >6 ED visits. Patients with elevated white blood cell counts, elevated platelet counts, and low hemoglobin levels exhibited higher risk for frequent ED utilization and could be candidates for early and aggressive therapy with disease modifying agents.
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The severe pain, ischemia and organ damage that characterizes sickle cell disease (SCD) is caused by vaso-occlusion, which is the blockage of blood vessels by heterotypic aggregates of sickled erythrocytes and other cells. Vaso-occlusion is also a vasculopathy involving endothelial cell dysfunction, leukocyte activation, platelet activation and chronic inflammation resulting in the multiple adhesive interactions between cellular elements. Since platelets mediate inflammation as well as thrombosis via release of pro- and anti-inflammatory molecules, we hypothesized that platelets may play an active inflammatory role in SCD by secreting increased amounts of cytokines. Since platelets have been shown to contain mRNA and actively produce proteins, we also hypothesized that SCD platelets may contain increased cytokine mRNA. In this cross-sectional study, we sought to compare both the quantity of cytokines secreted and the cytokine mRNA content, between SCD and control platelets. We measured the secretion of Th1, Th2, and Th17-related cytokines from platelets in a cohort of SCD patients. We simultaneously measured platelet mRNA levels of those cytokines. Platelets from SCD patients secreted increased quantities of IL-1β, sCD40L, and IL-6 compared to controls. Secretion was increased in patients with alloantibodies. Additionally, mRNA of those cytokines was increased in SCD platelets. Platelets from sickle cell patients secrete increased amounts of inflammatory cytokines, and contain increased cytokine mRNA. These findings suggest a novel immunological role for platelets in SCD vasculopathy, in addition to their thrombotic role, and strengthen the rationale for the use of anti-platelet therapy in SCD.
Article
Platelets play a critical role at the interphase of thrombosis and inflammation, key features in haemolysis-associated disorders. Exercising this role requires expression of pattern recognition receptors by platelets, including toll-like receptor 4 (TLR4) and nucleotide-binding domain leucine rich repeat containing protein 3 (NLRP3), the latter forming intraplatelet multiprotein inflammasome complexes. Platelets are a potential target of various damage-associated molecular pattern (DAMP) molecules, such as free haem, a degradation by-product of haemoglobin oxidation during haemolysis, and high-mobility group box 1 (HMGB1), a DNA-binding protein released by dying or stressed cells and activated platelets. We have recently identified platelet TLR4, NLRP3, and Bruton tyrosine kinase (BTK) as critical regulators of platelet aggregation and thrombus formation, suggesting that the BTK inhibitor ibrutinib is a potential therapeutic target. Increasing evidence suggests that these and other DAMP-driven signalling mechanisms employed by platelets might be key in mediating inflammation and thrombosis encountered in haemolytic disorders. However, the precise regulatory triggers and their clinical relevance are poorly understood. We provide new insights into these less-well characterised platelet mechanisms, which are potentially targetable in haemolytic disorders.
Article
Background: Foetal haemoglobin (HbF, α2γ2) retards polymerisation of haemoglobin (Hb) in sickle cell anaemia (SCA). In Nigeria, studies on the levels of HbF and its relationship with haematological indices are scanty. Objectives: This study evaluated HbF concentrations of children with SCA from Southwestern Nigeria and correlated the levels with various haematological indices. Materials and Methods: HbF levels were quantified by high‑performance liquid chromatography and haematological parameters determined with automated haemoanalyser. The relationship between steady‑state HbF levels and blood parameters were assessed by statistical analyses. Results: The mean HbF of the 91 children with SCA (9.6% ± 5.9%) was significantly higher than 0.5 ± 0.7% for the 91 age‑ and sex‑matched controls, P < 0.001. About two‑third of children with SCA, sixty (65.9%) had low HbF levels (HbF of < 10%) whereas about one‑third, 31 (34.1%) had high HbF level (HbF of ≥ 10%). The mean Hb concentration, haematocrit (Hct) and total red blood cell count were significantly lower amongst children with SCA, whereas the total white blood cell (WBC) counts, neutrophils, monocyte and lymphocyte percent, platelet counts, mean corpuscular Hb (MCH) and MCH concentration were significantly higher. HbF had a positive but weak correlation with Hct (r = 0.24, P = 0.014), Hb concentration (r = 0.21, P = 0.047) and red cell distribution width (r = 0.25, P = 0.015) and an inverse correlation with WBC count (r = -0.23, P = 0.038). Conclusion: Children with SCA had higher levels of HbF than matched controls. HbF had an inverse correlation with the WBC count and direct relationship with Hct and Hb concentration. It is recommended that routine determination of HbF and its induction are essential to maintain optimal haematological state of patients with SCD.