CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 7, August 2012
AFRICA
391
1.91, 95% CI: 1.08–3.36,
p
=
0.03).
Indian patients were most likely to report a family history
of heart disease (66% of patients, OR 3.96, 95% CI: 2.46–6.37,
p
<
0.001 compared toAfrican descent). There were no significant
differences between ethnicities in diabetes co-morbidity, despite
a relatively high prevalence in Indian patients (14% compared to
9% in all other ethnic groups;
p
=
0.08).
African patients were significantly more likely to be
diagnosed with hypertensive heart failure (HT-HF) (OR 2.14,
95% CI: 1.48–3.11) and least likely to be diagnosed with
coronary artery disease (CAD) (OR 0.16, 95% CI: 0.12–0.22,
p
<
0.001 for both). Despite representing only 12% of patients in
this sub-study, white Europeans and Indian patients accounted
for 40% of all primary diagnoses of CAD.
Lipid profiles
There were significant (unadjusted) differences in lipid profiles
across ethnicities with increasing gradients in TC, LDL-C and
TG levels (all
p
<
0.001), however there were no differences
observed between ethnicities in HDL-C values (
p
=
0.24)
(Fig. 1). Overall, females had higher HDL-C values than males:
1.21
±
0.50 vs 1.09
±
0.50 mmol/l (
p
<
0.0001). While females
had higher HDL-C levels than males in the African (
p
<
0.001),
white European (
p
=
0.04) and Indian (
p
=
0.01) groups, there
was no difference in HDL-C levels in those of mixed ancestry:
1.33
±
0.42 mmol/l in females vs 1.19
±
0.60 mmol/l in males
(
p
=
0.23).
When compared to other ethnicities (pooled analyses),
patients of African descent had significantly lower TC, LDL-C
and TG levels (
p
<
0.01 for all comparisons). African patients
were significantly less likely to have high TC (OR 0.33, 95%
CI: 0.25–0.44), high LDL-C (OR 0.34; 95% CI: 0.25–0.47) and
high TG levels (OR 0.37, 95% CI: 0.27–0.50) compared to other
ethnicities (all
p
<
0.001).
In gender- and age-adjusted linear regression models, BMI
was positively but modestly associated with TC, LDL-C and TG
levels (all
p
<
0.01). The estimated mean increase in TC level
was 0.09 mmol/l (95% CI: 0.01–0.85;
p
<
0.0001) for a 5-kg/
m
2
increase in BMI, while LDL-C increased 0.05 mmol/l for
the same change in BMI (95% CI: 0.03–0.1,
p
=
0.002). There
was also a positive association between TG values and BMI; a
5-kg/m
2
increase in BMI was associated with a mean 0.07-mmol/l
increase in TG level (95% CI: 0.04–0.1,
p
<
0.001). There was
no association between BMI and HDL-C level (
p
=
0.8).
Table 2 shows the independent predictors of dyslipidaemia in
this cohort. Female gender was a positive predictor for high TC
levels and females were less likely to have a low HDL-C value.
TABLE 1. CLINICALAND DEMOGRAPHIC PROFILEACCORDINGTO ETHNICITY
African descent
(
n
=
1823)
White European
(
n
=
142)
Mixed ancestry
(
n
=
87)
Indian
(
n
=
133)
p
-value
Demographic profile
Mean age (years)
56.2
±
15.8
57.3
±
12.7
55.7
±
12.1
58.6
±
11.9
0.29
Female
1104 (61%)
51 (36%)
35 (40%)
68 (51%)
<
0.001
<
6 years’ formal education
856 (47%)
33 (23%)
31 (36%)
71 (53%)
<
0.001
Soweto origin
856 (47%)
2 (1%)
2 (2%)
0 (0%)
<
0.001
Clinical presentation
Total cholesterol (mmol/l)
4.1
±
1.3
4.6
±
1.3***
4.8
±
1.3***
5.0
±
1.1***^
<
0.001
Low-density lipoprotein cholesterol (mmol/l)
2.4
±
1.0
2.7
±
1.0*
2.8
±
1.1*
3.0
±
1.0***
<
0.001
High-density lipoprotein cholesterol (mmol/l)
1.2
±
0.5
1.2
±
0.5
1.2
±
0.5
1.2
±
0.4
0.24
Median triglycerides (mmol/l)
1.1 (0.8–1.6)
1.4 (1.0–2.1) *** 1.4 (0.9–1.9)** 1.8 (1.2–2.7) ***^
#
<
0.001
Median serum CRP (
n
=
664, mg/l)
16.6 (6.2–83.9)
27.0 (8.0–98.0)
25.0 (6.3–50.2)
7.9 (2.7–27.0)
0.03
Systolic blood pressure (mmHg)
136.6
±
28.2
130.1
±
27.1*
133.7
±
25.9
133.8
±
24.0
0.05
Diastolic blood pressure (mmHg)
77.8
±
15.4
72.8
±
12.8 *
75.8
±
15.0
73.7
±
12.2*
<
0.001
Body mass index (
n
=
1593, kg/m
2
)
29.7
±
7.5
29.7
±
9.8
25.6
±
7.1*^^ 28.2
±
5.7
<
0.001
Prevalence of dyslipidaemia
High total cholesterol (mmol/l)
715 (39%)
76 (54%)
52 (60%)
93 (70%)
<
0.001
High low-density lipoprotein cholesterol (mmol/l)
718 (44%)
68 (55%)
47 (60%)
85 (72%)
<
0.001
High triglycerides (mmol/l)
386 (23%)
44 (36%)
33 (41%)
66 (56%)
<
0.001
Low high-density lipoprotein cholesterol (mmol/l)
1044 (63%)
86 (66%)
47 (57%)
74 (62%)
0.58
Prevalence of other risk factors
Obese (
>
30 kg/m
2
)
579 (43%)
31 (37%)
12 (19%)
29 (30%)
<
0.001
Type 2 diabetes
164 (9%)
9 (6%)
6 (7%)
18 (14%)
0.34
Current smoker
833 (46%)
104 (73%)
63 (72%)
57 (43%)
<
0.001
Family history of CVD
765 (42%)
71 (50%)
34 (39%)
88 (66%)
<
0.001
Primary diagnosis
Hypertension
380 (21%)
15 (11%)
23 (26%)
33 (25%)
0.42
Hypertensive heart failure
525 (29%)
14 (10%)
14 (16%)
22 (17%)
<
0.001
Coronary artery disease
179 (10%)
74 (52%)
23 (26%)
61 (46%)
<
0.001
CRP
=
C-reactive protein; CVD
=
cardiovascular disease; median (interquartile range); Kruskal-Wallis test performed.
Tukey’s
post-hoc
tests: *
p
<
0.05; **
p
<
0.01; ***
p
<
0.001 compared to African descent. ^
p
<
0.05; ^^
p
<
0.01 compared to white Europeans;
##
p
<
0.01
compared to mixed ancestry.
