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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018
370
AFRICA
Longitudinal investigation
In Table 2 we demonstrate qualitative (attempts to change
lifestyle over three years) and quantitative lifestyle changes.
Blacks reported higher attempts to change alcohol-consumption
habits (
p
<
0.001) over three years, in comparison to whites.
However, quantitative
γ
-GT levels, as a surrogate marker of
alcohol consumption, did not support this finding. Dietary
habits also did not change over time; in fact observed central
obesity, as demonstrated by waist circumference, increased in
both ethnic groups (
p
<
0.001).
Black Africans
Table 3 represents risk-marker changes over three years. Blacks
reported statistically significant increases in stress, DefS and
avoidance (
p
<
0.001), while depressive symptoms and social
support decreased (
p
<
0.001). Only seeking less social support
and avoidance were clinically significant (
d
=
–1.10 and 0.87).
Spiritual-centred coping increased (
p
<
0.05) with small effect.
Chronic depression (38%) and hypertensive status (68%) were
apparent in blacks at follow up.
For depression status, a change in 24 persons from positive at
baseline to negative at follow up occurred. This was statistically
significantly less than the 37 persons who changed from negative
to positive (
p
=
0.001), which was also clinically relevant (OR
=
3.33). In blacks, increased defensiveness (OR 1.08,
p
≤
0.05)
and ritual-centred coping (OR 1.27,
p
≤
0.01;
d
-values
>
0.5)
predicted chronic depression (Table 4). The changes in their
depressive symptoms predicted 24-hour hypertension (OR 1.11,
p
=
0.04) (Table 5). Sensitivity analysis considering HIV-positive
status and use of hypertension medication did not change the
outcome of the current data.
White Africans
Among whites, avoidance or loss-of-control and using group-
activity (collectivistic) coping significantly increased over three
years (
p
<
0.05), while the latter had a medium effect (
d
=
0.44).
They had minor decreases in DBP (
p
<
0.001,
d
=
–0.21) and SBP
(
p
=
0.04,
d
=
–0.11). Chronic depression (19%) and an increase
in hypertensive status (35%) occurred in whites (
p
=
0.02), having
clinical relevance (OR
=
2.14). No similar associations existed
in whites.
Table 3. Comparing differences over a three-year period by ethnic status
Blacks (
n
=
173)
Whites (
n
=
186)
Baseline/
follow up
Difference
(95% CI)
p
-values
d
-values
Baseline/
follow up
Difference
(95% CI)
p
-values
d
-values
Stress perception
1.86/1.93
1.23 (0.0,0.1)
≤
0.001
0.20
1.90/1.94
0.04 (–0.0, 0.1)
0.180 0.13
Depressive symptoms
9.42/8.19
–1.16 (–1.9, –0.4)
0.004 –0.21
5.56/6.00.
0.24 (–0.4, 0.8)
0.435 0.10
Coping scores (CSI)
Defensive
28.2/28.7
0.5 (–0.3, 1.2)
≤
0.001
0.11
29.1/28.8
–0.3 (–0.9, 0.6)
0.664 –0.04
Social support
25.6/20.3
–5.3 (–6.2, –4.5)
≤
0.001 –1.10
18.7/18.1
–0.6 (–1.4, 0.1)
0.093 –0.13
Avoidance
21.1/24.3
3.2 (2.4, 4.2)
≤
0.001
0.87
23.8/24.7
0.9 (0.1, 1.8)
0.035 0.18
Culture-specific coping scores (ACSI)
Cognitive/emotional
15.9/15.5
–0.4 (–1.5, 0.6)
0.411 –0.07
10.0/10.1
0.1 (–0.1, 1.5)
0.100 0.12
Spiritual-centred
13.4/14.1
0.7 (–0.0, 1.5)
0.050
0.12
11.3/11.4
0.1 (–0.6, 0.8)
0.757 0.02
Collectivistic
12.5/13.1
0.6 (–0.2, 1.4)
0.145
0.11
8.6/10.5
1.9 (1.2, 2.5)
≤
0.001 0.44
Ritualistic
2.3/2.4
0.1 (–0.3, 0.4)
0.720
0.03
0.3/0.3
0.0 (–0.1, 0.1)
0.928 –0.01
24-h ambulatory blood pressure monitoring
SBP, mmHg
133/136
3.0 (0.6, 4.8)
0.011
0.17
125/123
–2.0 (–2.6, –0.1)
0.037 –0.11
DBP, mmHg
84/84
0.0 (–1.1, 1.5)
0.756
0.02
77/76
–1.0 (–2.6, –0.9)
≤
0.001 –0.21
†
Depression: %
Δ
[OR (95% CI)]
2.77 [1.5 (0.9, 2.6)]
0.10
4.17 [1.20 (0.3, 1.4)]
0.27
†
Depression %: (BL+, FU–)/(BL–, FU+)
24/37
18/12
†
Hypertension: %
Δ
[OR (95% CI)]
0.29 [0.82 (0.4, 1.7)]
0.60
5.82 [2.14 (1.1, 4.0)]
0.02
†
Hypertension %: (BL+, FU–)/(BL–, FU+)
17/14
14/30
Chronic depression, %
38
19
0.05
0.30
Chronic hypertension, %
68
35
≤
0.001 0.49
CSI, coping strategy indicator; ACSI, Africultural coping systems inventory; SBP, systolic blood pressure; DBP, diastolic blood pressure.
Values presented as arithmetic mean at baseline/follow up as well as the difference over three years (95% CI).
p
-values were obtained from dependent sample
t
-tests;
d
-value effects: 0.2
=
small; 0.5
=
medium; 0.8
=
large
†
McNemar chi-square equation values are presented as percentage difference over three years followed by the odds ratio (± 95% CI); OR-value effects: 1.5
=
small,
2.5
=
medium, 4.25
=
large.
(BL+, FU–), frequency at baseline positive but negative at follow up; (BL–, FU+), frequency at baseline negative but positive at follow up; %, ratio of frequencies.
Table 4. Probability of coping-strategy changes over three years to
predict chronic depression in a black teachers’ cohort
Chronic depression
Changes
Nagelkerke
R
2
Odds
ratio
5th
percentile
95th
percentile
p
-values
Δ
Defensive coping
0.08
1.08 1.01
1.15
0.033
Δ
Ritual-centred coping
0.12
1.27 1.09
1.47
0.002
Coping strategies were added as co-variates in separate models with
a priori
log-normalised variables, age, waist circumference, physical activity,
γ
-GT and
cotinine. OR-value effects: 1.5
=
small; 2.5
=
medium; 4.25
=
large.
Table 5. Probability of changes in depressive symptoms to predict
24-hour systolic hypertension in a black teachers’ cohort
24-h systolic hypertension
Changes
Nagelkerke
R
2
Odds
ratio
5th
percentile
95th
percentile
p-
values
Δ
Depressive symptoms
0.30
1.11 1.01
1.16
0.036
Coping strategies were added as co-variates in separate models with
a priori
log-normalised variables, age, waist circumference, physical activity,
γ
-GT and
cotinine. OR-value effects: 1.5
=
small; 2.5
=
medium; 4.25
=
large.