CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 1, January/February 2011
20
AFRICA
smokers in the African group. Both values of PWV, as a measure
of arterial stiffness, were significantly higher in African smokers
than non-smokers. Furthermore, HDL-C levels remained higher
in African smokers than their non-smoking counterparts, even
after adjusting for age, gender, BMI and WC.
In Table 3 the Caucasian smokers and non-smokers are
compared. There were fewer Caucasian smokers than non-
smokers. HR and CO values were higher in the smokers, whereas
TPR and Cwk values were lower in the smokers after adjust-
ments were made. Smokers had lower HDL-C and higher TG and
hs-CRP levels. Cotinine differed significantly throughout, with
significantly higher values in smokers, as expected.
Further analyses were performed in which smoking was
correlated with cardiovascular variables (SBP, DBP, HR, CO,
Cwk, PWV), hs-CRP and lipid (HDL-C, LDL-C, TG) levels. To
correlate smoking with these variables, smoking was viewed as
either chronic exposure, using the subjects’ duration of smoking
(obtained from questionnaires), or acute exposure, using serum
cotinine values.
Table 4 correlates smoking with the above variables in
Africans. The results showed that chronic exposure to smok-
ing (smoking duration) had significant correlations with most
cardiovascular variables in the whole African group before
adjustments were made. This trend remained quite similar after
dividing the African group according to gender. PWV (Fig. 1),
CO and Cwk also showed strong, significant correlations with
smoking duration (
p
≤
0.001).
The relationships between cotinine levels and cardiovascular
variables were somewhat weaker in the whole African group. A
positive correlation was found between cotinine and PWV, and
weak correlations with TPR and Cwk. HDL-C levels correlated
positively and significantly with smoking in the African group.
TABLE 1. DESCRIPTIVE STATISTICS OF THE POPULATION STUDIED
Variable
Africans (
n
=
258)
Caucasians (
n
=
372)
p
-value
Age (years)
41.6
±
0.82 (39.9; 43.1) 40.4
±
0.69 (39.0; 41.7) 0.287
Gender (men/women)
127/131
161/211
Height (m)
1.63
±
0.01 (1.62; 1.64) 1.72
±
0.00 (1.71; 1.73)
≤
0.001
Weight (kg)
63.5
±
1.10 (61.3; 65.7) 82.2
±
1.03 (80.2; 84.2)
≤
0.001
BMI (kg/m
2
)
24.0
±
0.45 (23.1; 24.9) 27.7
±
0.31 (27.1; 28.3)
≤
0.001
WC (cm)
78.7
±
0.85 (77.0; 80.4) 87.4
±
0.79 (85.8; 88.9)
≤
0.001
SBP (mmHg)
127
±
1.39 (124; 129) 119
±
0.84 (118; 121)
≤
0.001
DBP (mmHg)
85
±
0.87 (83; 87)
78
±
0.52 (77; 79)
≤
0.001
HR (beats/min)
70.0
±
0.82 (68.3; 72.0) 68.0
±
0.50 (67.0; 68.4) 0.008
SV (ml)
75.2
±
1.39 (72.5; 77.9) 90.8
±
1.27 (88.4; 93.3)
≤
0.001
CO (l/min)
4.99
±
0.09 (4.81; 5.17) 6.12
±
0.09 (5.94; 6.31)
≤
0.001
TPR (mmHg.s/ml) 1.39
±
0.04 (1.31; 1.46) 1.06
±
0.02 (1.02; 1.09)
≤
0.001
Cwk (ml/mmHg)
1.60
±
0.03 (1.54; 1.67) 2.10
±
0.03 (2.04; 2.17)
≤
0.001
C-R PWV (m/s)
8.67
±
0.10 (8.47; 8.87) 7.63
±
0.07 (7.48; 7.77)
≤
0.001
C-P PWV (m/s)
8.18
±
0.10 (7.98; 8.38) 7.82
±
0.06 (7.69; 7.94)
≤
0.001
HDL-C (mmol/l)
1.57
±
0.04 (1.49; 1.65) 1.39
±
0.02 (1.35; 1.44)
≤
0.001
LDL-C (mmol/l)
2.35
±
0.06 (2.24; 2.46) 3.76
±
0.07 (3.63; 3.89)
≤
0.001
TG (mmmol/l)
1.38
±
1.01 (1.36; 1.39) 1.46
±
1.01 (1.44; 1.48)
≤
0.001
hs-CRP (mg/l)
1.90
±
1.03 (1.80; 2.01) 1.65
±
1.02 (1.59; 1.72)
≤
0.001
Smoking duration
(years)
13.9
±
0.82 (12.3; 15.5) 12.7
±
1.46 (9.82; 15.7) 0.490
Cotinine (ng/ml)
199
±
10.8 (178; 221) 43.2
±
5.02 (33.3; 53.1)
≤
0.001
n
smokers (%)
161 (62.4)
54 (14.5)
≤
0.001
n
male smokers (%)
96 (76.0)
34 (21.1)
≤
0.001
n
female smokers (%)
65 (50.0)
20 (9.48)
≤
0.001
Income/mth:
≤
R1000
232 (90.0%)
23 (6.18%)
≤
0.001
R1000–R2000
22 (8.52%)
29 (7.79%)
≤
0.001
R2000–R3000
3 (1.16%)
14 (3.76%)
≤
0.001
R3000–R4000
0 (0.00 %)
23 (6.18%)
≤
0.001
R4000–R5000
1 (0.39%)
26 (6.99%)
≤
0.001
≥
R5000
0 (0.00%)
244 (65.6%)
≤
0.001
Values are expressed as the mean
±
standard error (95% CI). The mean values
for TG and hs-CRP were logarithmically transformed and geometric means used.
BMI: body mass index; WC: waist circumference; SBP: systolic blood pressure;
DBP: diastolic blood pressure; SV: stroke volume; CO: cardiac output; TPR: total
peripheral resistance; Cwk: Windkessel compliance; C-R PWV: carotid-radialis
pulse wave velocity; C-P PWV: carotid-dorsalis pedis pulse wave velocity;
HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein
cholesterol; TG: triglycerides; hs-CRP: high-sensitivity C-reactive protein.
TABLE 2: COMPARISON BETWEENAFRICAN SMOKERS
AND NON-SMOKERS
Variable
African non-smokers
(
n
=
93)
African smokers
(
n
=
152)
p
-value
Age (years)
37.5
±
1.36 (34.8; 40.2) 44.0
±
0.98 (42.1; 46.0)
≤
0.001
Gender (men/women)
31/66
96/65
Height (m)
1.62
±
0.01 (1.60; 1.63) 1.64
±
0.01 (1.63; 1.65) 0.103
Weight (kg)
71.4
±
1.99 (67.4; 75.4) 58.8
±
1.15 (57.0; 61.0)
≤
0.001
BMI (kg/m
2
)
27.4
±
0.81 (25.8; 29.0) 22.1
±
0.47 (21.1; 23.0)
≤
0.001
WC (cm)
83.0
±
1.54 (79.9; 86.0) 76.3
±
0.95 (74.4; 78.2)
≤
0.001
SBP (mmHg)
124
±
2.64 (119; 129) 129
±
1.55 (126; 132)
0.079
DBP (mmHg)
84
±
1.19 (81.0; 87.2) 86
±
1.02 (84.0; 88.0)
0.393
HR (beats/min)
69.3
±
1.15 (67.0; 72.0) 70.3
±
1.13 (68.0; 73.0) 0.561
SV (ml)
80.1
±
1.58 (75.6; 85.0) 72.1
±
1.72 (69.0; 75.5) 0.005
CO (l/min)
5.31
±
0.16 (4.99; 5.63) 4.80
±
0.12 (4.57; 5.00) 0.006
TPR (mmHg.s/ml) 1.28
±
0.05 (1.18; 1.37) 1.46
±
0.05 (1.36; 1.57) 0.016
Cwk (ml/mmHg)
1.76
±
0.04 (1.66; 1.86) 1.50
±
0.04 (1.42; 1.58)
≤
0.001
C-R PWV (m/s)
8.05
±
0.16 (7.76; 8.35) 9.04
±
0.12 (8.79; 9.30)
≤
0.001
C-P PWV (m/s)
7.57
±
0.13 (7.25; 7.89) 8.55
±
0.10 (8.31; 8.79)
≤
0.001
HDL-C (mmol/l)
1.33
±
0.04 (1.25; 1.41) 1.72
±
0.06 (1.61; 1.84)
≤
0.001
LDL-C (mmol/l)
2.36
±
0.09 (2.18; 2.53) 2.35
±
0.07 (2.21; 2.50) 0.962
TG (mmmol/l)
1.35
±
1.01 (0.27; 0.32) 1.40
±
1.01 (0.32; 0.35) 0.015
hs-CRP (mg/l)
1.95
±
1.04 (0.59; 0.75) 1.88
±
1.04 (0.55; 0.70) 0.434
Cotinine (ng/ml)
43.7
±
9.13 (25.5; 61.8) 296
±
10.9 (274; 317)
≤
0.001
Comparison after adjustment for age, gender, BMI and WC
SBP (mmHg)
128
±
2.05 (124; 132) 126
±
1.55 (123; 129)
0.050
DBP (mmHg)
85
±
1.37 (82.1; 87.5) 85
±
1.03 (82.8; 87.0)
0.443
HR (beats/min)
70.1
±
1.38 (67.4; 73.0) 70.0
±
1.04 (68.0; 72.0)
0.539
SV (ml)
74.5
±
1.94 (70.7; 78.3) 75.2
±
1.48 (72.3; 78.2)
≤
0.001
CO (l/min)
4.91
±
0.13 (4.66; 5.17) 5.01
±
1.00 (4.81; 5.20)
≤
0.001
TPR (mmHg.s/ml) 1.40
±
0.06 (1.29; 1.51) 1.39
±
0.04 (1.30; 1.47) 0.006
Cwk (ml/mmHg)
1.59
±
0.03 (1.54; 1.65) 1.60
±
0.02 (1.56; 1.65)
≤
0.001
C-R PWV (m/s)
8.42
±
0.15 (8.12; 8.72) 8.81
±
0.11 (8.59; 9.03)
≤
0.001
C-P PWV (m/s)
8.00
±
0.12 (7.77; 8.23) 8.29
±
0.09 (8.12; 8.47)
≤
0.001
HDL-C (mmol/l)
1.44
±
0.07 (1.31; 1.57) 1.64
±
0.05 (1.54; 1.74)
≤
0.001
LDL-C (mmol/l)
2.39
±
0.09 (2.21; 2.58) 2.34
±
0.07 (2.20; 2.48) 0.809
TG (mmmol/l)
1.35
±
0.01 (0.27; 0.32) 1.40
±
0.01 (0.32; 0.35) 0.012
hs-CRP (mg/l)
0.63
±
0.04 (0.55; 0.71) 0.66
±
0.03 (0.59; 0.72) 0.392
Cotinine (ng/ml)
53.9
±
13.2 (27.8; 79.9) 288
±
9.96 (269; 308)
≤
0.001
Values are expressed as the mean
±
standard error (95% CI). The mean values
for TG and hs-CRP were logarithmically transformed and geometric means used.
PWV was also adjusted for MAP. BMI: body mass index; WC: waist circumfer-
ence; SBP: systolic blood pressure; DBP: diastolic blood pressure; SV: stroke
volume; CO: cardiac output; TPR: total peripheral resistance; Cwk: Windkessel
compliance; C-R PWV: carotis-radialis pulse wave velocity; C-P PWV: carotis-
dorsalis pedis pulse wave velocity; HDL-C: high-density lipoprotein cholesterol;
LDL-C: low-density lipoprotein cholesterol; TG: triglycerides; hs-CRP: high-
sensitivity C-reactive protein.
