CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 4, July/August 2022 AFRICA 173 traits were never added simultaneously into the models to avoid co-linearity. Logistic multiple regressions were used to indicate the probability or odds of personality traits (exposure) to increase or decrease the likelihood of meeting ethnic-specific cTnT cut-off points (outcome) with and without considering specific coping styles.4,13 An odds ratio (OR) > 1 is indicative of a higher likelihood of an outcome upon exposure, whereas an OR < 1 is indicative of a lower likelihood of an outcome upon exposure.51 An OR = 1 indicates that the outcome is not affected by the exposure.51 A statistical level of p < 0.05 indicated significance in all analyses. To ensure that the outcome of our regression analyses was not influenced by cases with atrial fibrillation (n = 4) and other lifestyle factors (waist circumference, physical activity), we repeated the regressions by excluding these cases and adjusting for waist circumference and physical activity. Results All three coping strategies and race showed interaction effects for neuroticism [race × DefS ≥ 31, (F(1,325) = 4.60; p = 0.033)]; [race × seeking social support coping ≥ 28, (F(1,325) = 4.18; p = 0.042]; [race × avoidance coping ≥ 23 (F(1,325) = 21.73; p < 0.001]. An interaction term was fitted for conscientiousness in DefS ≥ 31 groups (F(1,325) = 6.43; p = 0.012). No significant interactions were evident between gender and personality traits. We therefore stratified our groups according to race, but also divided each race into the respective coping strategies when associations were assessed in regression analyses, additionally adjusting for gender. In Table 1, Cohen’s d showed small to large effect sizes when comparing lifestyle and biochemical markers, mean coping and personality scores, as well as cardiac risk markers and medication usage. Only those variables showing statistically significant differences are now reported. Compared to Caucasians, Africans were younger (d = –0.25), consumed more alcohol (d = 0.63), engaged in less physical activity (d = –0.35), had less dyslipidaemia (d = –0.35), albeit higher hyperglycaemic values (d = 0.63). Although the number of Africans and Caucasians scoring high in DefS was similar, more Africans scored high on the seeking social support coping scale (φ = 0.43), whereas a greater number of Caucasians scored high on the avoidance coping scale (φ = 0.23). Africans also scored higher in neuroticism (d = 0.36), but lower in conscientiousness (d = –0.40) than Caucasians. When comparing cardiac and haemodynamic risk markers, Africans demonstrated lower cTnT levels (d = –0.37) and more were hypertensive (φ = 0.21), with higher 24-hour SBP (d = 0.50) and DBP (d = 0.65) than the Caucasians. Almost half of the African participants (48%) and 39% of the Caucasian participants showed cTnT values similar to or greater than the ethnic-specific cut-off points (Africans: 4.2 pg/ml, Caucasians: 5.6 pg/ml) that were previously shown to be predictive of 24-hour hypertension.4,13 Furthermore, φ-values for medication use showed low to medium effect sizes, which included greater usage of anti-hypertensives (φ = 0.24), thiazides (φ = 0.13), angiotensin converting enzyme inhibitors (φ = 0.19) and diabetes medication (φ = 0.13) in the Africans. Unadjusted longitudinal changes are presented in Table 2, where cTnT levels over time decreased in both races. Africans showed no significant three-year frequency variance in the ethnicspecific cTnT cut-off point of 4.2 pg/ml,4,13 while Caucasians showed low incidence (7%), with greater recovery (18%) from the 5.6 pg/ml cut-off point (OR: 2.67, p = 0.003). Table 3 presents correlations between coping scores and personality traits. In both Africans and Caucasians, DefS correlated positively with conscientiousness but inversely with neuroticism. A positive correlation was evident between DefS and openness to experience in Africans. The seeking social support coping score correlated positively with extraversion in the African group, but inversely in the Caucasian group. Furthermore, seeking social support coping in Caucasians was positively correlated with neuroticism, but inversely with conscientiousness. A positive correlation in the African group but an inverse relationship in the Caucasian group was evident between avoidance coping and neuroticism. In both the Africans and Caucasians, linear relationships did not exist (p > 0.05; r = 0) between personality traits and gene data (mitochondrial DNA, tyrosine hydroxylase C-824T SNP and telomere length). Caucasians showed no significant associations between %Δ cTnT and the independent variables in Table 4. In Africans, %Δ cTnT was inversely associated with conscientiousness (adjusted R2 = 0.14; β = –0.26, p = 0.034) in individuals scoring high in DefS. These coefficients show that when conscientiousness Table 3. Pearson correlations between personality traits and coping strategy scores in a bi-ethnic South African cohort Personality traits Defensive coping Seeking social support coping Avoidance coping r p r p r p Africans (n = 155) Extraversion 0.13 0.099 0.17 0.038 –0.03 0.718 Neuroticism –0.24 0.003 0.08 0.312 0.48 < 0.001 Conscientiousness 0.26 0.001 0.12 0.136 –0.10 0.210 Openness to experience 0.20 0.013 0.02 0.766 0.06 0.490 Agreeableness 0.15 0.063 0.15 0.065 0.05 0.504 Caucasians (n = 181) Extraversion 0.04 0.623 –0.18 0.018 0.09 0.213 Neuroticism –0.24 0.001 0.40 < 0.001 –0.15 0.049 Conscientiousness 0.17 0.025 –0.15 0.042 0.01 0.884 Openness to experience 0.04 0.584 0.07 0.350 0.01 0.906 Agreeableness 0.10 0.194 0.00 0.965 0.02 0.754 The values are displayed as the correlation coefficient and p-value to indicate significance. Table 2. Presenting longitudinal changes in cardiac troponin T in a bi-ethnic South African cohort Africans (n = 155) Caucasians (n = 181) Baseline; follow up (difference) p d Baseline; follow up (difference) p d cTnT (pg/ml) 4.50; 4.15 (–0.35) 0.020 –0.19 5.63; 5.08 (–0.56) < 0.001 –0.25 cTnT ≥ 4.2 pg/ml cTnT ≥ 5.6 pg/ml Incidence, n (%) 30 (19) 12 (7) Recovery, n (%) 31 (20) 32 (18) OR (95% CI), p 1.03 (0.63–1.71), 0.898 2.67 (1.37–5.18), 0.003 Data presented as unadjusted mean differences between baseline and follow up (change over time) and were determined using dependent sample t-tests. cTnT, cardiac troponin T; NT-proBNP, N-terminal pro-brain natriuretic peptide. Effect sizes are indicated by Cohen’s d-values for dependent sample t-tests: 0.2 = small effect, 0.5 = medium effect and 0.8 = large effect. Incidence, cTnT ≥ 4.2 pg/ml or cTnT > 5.6 pg/ml (negative at baseline becomes positive at follow up) Recovery, cTnT ≥ 4.2 ng/l or cTnT > 5.6 pg/ml (positive at baseline recovers to negative at follow up). OR value effects: 1.5 = small; 2.5 = medium; 4.25 = large.
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