CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 1, February 2012
38
AFRICA
Haematological parameters such as haematocrit, reticulocyte
count, white blood cell count with differentials, and haemoglobin
electrophoresis were obtained.
Data were presented as means
±
standard deviation. In order
to examine the effect of anaemia on the variables, the subjects
were classified, based on the haematocrit values, into four
classes in accordance with the World Health Organisation clas-
sification of anaemia, as follows: class 1, normal (haematocrit
≥
36%); class 2, mild anaemia (haematocrit 30–35.9%); class
3, moderate anaemia (haematocrit 21–29.9%); class 4, severe
anaemia (haematocrit 18–20.9%).
9
Inter-class differences in blood pressures in the patients
were compared by one-way analysis of variance and
post hoc
multiple comparison of means using the Tukey’s honestly
significant difference test. Intra-class differences in parameters
between patients and controls in the same haematocrit class
were analysed using the independent Student’s
t
-test. All statisti-
cal analyses were carried out using the Statistical Packages for
Social Sciences (SPSS Inc, Chicago, Illinois) software version
11.0. Statistical tests with probability values less than 0.05 were
considered statistically significant.
Results
The age and gender distribution of the subjects are shown in
Table 1. The mean ages for patients and controls were 28.27
±
5.58 (range 18–44) and 28.37
±
5.91 (range 18–45) years,
respectively. There were no statistically significant age and
gender differences in patients and controls. The study subjects
had statistically significantly lower mean values than the controls
in the measurement of height, weight, body mass index and body
surface area (
p
<
0.001) (Table 1).
The ankle systolic blood pressure was lower in sickle cell
anaemia patients than in the controls (
p
<
0.001) (Table 2). The
ratio of the systolic ankle-to-brachial blood pressure (ankle–
brachial systolic blood pressure index) was compared in patients
and controls (Table 3). The observed mean indices were 0.88
±
0.09 and 1.03
±
0.06, respectively for patients and controls. This
difference was statistically significant (
p
<
0.001). Seventy three
per cent (73.33%) of the patients had ankle–brachial index less
than 0.9, compared with controls (5%). This was also significant
(
p
<
0.001).
Table 2 compares the mean values for the physiological
parameters in the patients in the three separate categories,
based on their haematocrit levels, using analysis of variance.
Significant differences in mean values were observed in the
brachial systolic blood pressure (
F
=
6.029;
p
=
0.004), ankle
systolic blood pressure (
F
=
8.373;
p
=
0.001), ankle diastolic
blood pressure (
F
=
4.543;
p
=
0.015) and ankle–brachial index
(
F
=
3.260;
p
=
0.046), as well as pulse pressure (
F
=
5.747;
p
=
0.005).
Pair-wise
post hoc
multiple comparisons of means using
the Tukey’s honestly significant difference test showed that the
observed difference in systolic blood pressure was accounted
for by the difference in haematocrit between the moderate and
TABLE 1. AGE, GENDERANDANTHROPOMETRIC DATA
Parameters
SCA
Mean (SD)
Controls
Mean (SD)
t
-test
p
-value
Age (years)
28.27 (5.58) 28.37 (5.91) 0.987 0.924
Gender [frequency (%)]
Male
31 (50)
31 (50)
0.00 1.00
a
Female
31 (50)
31 (50)
Total
62
62
Weight (kg)
54.97 (10.61) 67.35 (8.37) 7.20
<
0.001*
Height (m)
1.62 (0.14) 1.72 (0.07) 4.960
<
0.001*
Body surface area (m
2
)
1.62 (0.03) 1.78 (0.14) 3.723
<
0.001*
Body mass index (kg/m
2
) 20.47 (2.73) 23.87 (3.22) 6.181
<
0.001*
*Statistically significant,
a
Chi-square. SCA: sickle cell anaemia.
TABLE 2. PHYSIOLOGICAL PARAMETERS IN SICKLE CELLANAEMIA; COMPARISONWITH HAEMATOCRIT LEVELS
Parameters
Mean (SD) haematocrit levels
F statistic
p
-value
Mild
Moderate
Severe
Age
26.11 (3.59)
23.60 (5.35)
25.18 (7.48)
0.922
0.402
Pulse rate
90.89 (13.57)
86.45 (8.36)
89.54 (5.54)
1.214
0.304
Brachial SBP
115.11 (13.57)
122.85 (9.34)
110.91 (13.75)
6.029
0.004*
Brachial DBP
69.78 (12.21)
64.60 (8.84)
61.87 (4.05)
2.083
0.134
Pulse pressure
45.33 (10.28)
58.25 (12.19)
49.09 (12.21)
5.747
0.005*
MAP
74.53 (28.58)
83.42 (6.82)
78.49 (6.39)
2.210
0.119
Ankle SBP
116.67 (13.23)
112.90 (13.09)
96.54 (10.77)
8.373
0.001*
Ankle DBP
73.33 (12.25)
67.15 (10.17)
60.00 (6.32)
4.543
0.015*
Ankle/brachial index
1.01 (0.06)
0.90 (0.04)
0.87 (0.09)
3.260
0.046*
*Statistically significant, DBP: diastolic blood pressure, SBP: systolic blood pressure, MAP: mean arterial blood pressure.
TABLE 3. PHYSIOLOGIC DATA IN PATIENTSAND CONTROLS
Parameters
SCA
mean (SD)
Controls
mean (SD)
t
-test
p
-value
Pulse rate
(beat/min)
87.68 (8.91)
72.13 (6.79) 11.062
<
0.001*
Brachial systolic BP
(mmHg)
119.50 (11.70) 121.2 (8.97) 0.527 0.599
Brachial diastolic
BP (mmHg)
64.867 (8.95)
76.88 (6.18) 8.629
<
0.001*
Brachial pulse
pressure (mmHg)
54.63 (12.87) 44.31 (10.91) 4.735 0.001*
Ankle BP (mmHg) 105.47 (14.23)
a
66.77 (10.52)
b
124.87 (9.32)
a
71.67 (13.20)
b
6.826
2.454
<
0.001*
0.016*
Ankle brachial
systolic BP index
0.88 (0.09)
1.03 (0.06)
6.567
<
0.001*
Mean brachial
arterial BP (mmHg)
81.18 (12.65)
91.71 (5.47) 5.850
<
0.001*
Haematocrit (%)
24.07 (3.10)
38.65 (1.97) 30.589
<
0.001*
*Statistically significant,
a
systolic,
b
diastolic. BP: blood pressure, SCA:
sickle cell anaemia.
