CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 2, March/April 2022 AFRICA 69 were correlations with the indexed and non-indexed ESD and ESD of the LV. Of the analysed right-sided parameters (Table 7), fewer correlations were observed. In the controls the interleukin-6 levels correlated negatively with the right ventricle (RV) fractional area change (FAC) (r = –0.389, p < 0.01) and positively with the end-systolic area (ESA) of the RV (r = 0.286, p < 0.05). In the pre-eclampsia group, the levels correlated negatively with the E/e′ ratio of the tricuspid inflow (r = –0.367, p < 0.05) and positively with the FAC (r = 0.325, p < 0.05). There were no correlations in the whole study group, the gestational hypertension and the combined hypertension groups. Discussion The presence of higher levels of interleukin-6 in women with gestational hypertension and pre-eclampsia in our study confirms the inflammatory component and endothelial dysfunction in these conditions.27,28 Similar to our study, a number of other studies also found elevated interleukin-6 levels in women with pre-eclampsia,29-32 while a study by Borekci et al. did not find such an association.33 In a study by Xiao et al.,34 104 women with pre-eclampsia were analysed and compared to 75 controls, and significantly elevated levels were found in both early- and late-onset severe forms, but not in the mild cases. In the pre-eclampsia group, there was a significant difference in levels between the mild and severe forms, but no difference between early and late onset of the disease. Similarly, in our study there was no statistical difference when comparing between early and late onset of both hypertensive disorders, however, only the early-onset disorder had statistically higher interleukin-6 levels compared to the controls. This finding could be in line with the hypothesis of several authors of the presence of different risk factors and underlying pathogenic mechanisms for the development of early- versus late-onset Table 5. Correlation coefficients between interleukin-6 levels and certain characteristics of the women Characteristics All women Controls GH PE Maternal age 0.002 –0.105 0.171 0.061 Gestational age 0.101 0.488*** –0.039 –0.068 BMI before pregnancy 0.266** 0.305* 0.065 –0.007 Current BMI 0.284** 0.466** 0.103 –0.040 BSA 0.223* 0.468** –0.101 –0.085 Current weight gain 0.169 0.382** 0.069 0.009 Maximum SBP – – 0.275 0.045 Maximum DBP – – –0.001 0.255 *p < 0.05, **p < 0.01, **p < 0.001 GH: gestational hypertension; PE: pre-eclampsia; BMI: body mass index; BSA: body surface area; SBP: systolic blood pressure; DBP: diastolic blood pressure. Table 6. Correlation coefficients between interleukin-6 levels and left-sided echocardiographic parameters Parameters Whole study group Controls GH PE GH + PE AP diameter of LA 0.239** 0.318* 0.081 0.139 0.089 Ind AP diameter of LA 0.032 –0.122 0.171 0.104 0.132 Ind LA volume 0.094 –0.108 0.033 0.212 0.107 Septum (diastolic) 0.184* 0.285* –0.105 –0.158 –0.133 Posterior wall (diastolic) 0.118 0.210 –0.118 –0.109 –0.102 EDD 0.293** 0.356* 0.117 0.358* 0.238* ESD 0.317*** 0.401** 0.219 0.333* 0.268* Ind EDD 0.085 –0.065 0.187 0.316 0.257* Ind ESD 0.128 0.021 0.252 0.353* 0.278* EDV biplane 0.186* 0.179 –0.171 0.327* 0.078 Ind EDV biplane 0.061 –0.070 –0.207 0.407* 0.112 ESV biplane 0.146 0.225 –0.193 0.227 0.000 Ind ESV biplane 0.047 0.022 –0.192 0.220 0.011 LVMI 0.234** 0.441** 0.221 –0.025 0.081 EF (S) –0.023 –0.130 0.152 0.040 0.099 SV (VTI) 0.215* 0.322* 0.052 0.150 0.097 Cardiac index 0.162 0.135 0.163 0.237 0.219 E/A 0.069 0.007 0.295 –0.129 0.089 E–DT –0.128 0.032 –0.019 –0.140 –0.066 e′ medial –0.097 –0.271 0.357* 0.079 0.189 e′ lateral –0.133 –0.232 0.110 0.047 0.061 e′ mean –0.112 –0.258 0.244 0.074 0.137 E/e′ mean 0.206* 0.176 0.123 –0.209 –0.003 S medial –0.174 –0.173 0.123 –0.178 –0.046 S lateral –0.255** –0.225 0.076 –0.300 –0.143 LV GLS 0.211* 0.220 –0.146 –0.140 –0.093 *p < 0.05, **p < 0.01, ***p < 0.001 GH: gestational hypertension; PE: pre-eclampsia; AP: anterior–posterior; LA: left atrium; ind: indexed to BSA; EDD: end-diastolic dimension; ESD: end-systolic dimension; EDV: end-diastolic volume of the left ventricle; ESV: end-systolic volume of the left ventricle; LVMI: left ventricular mass index; EF (S): ejection fraction of the left ventricle, Simpson’s method; SV: stroke volume, calculated using VTI; E/A: ratio of the E wave and A wave of the mitral flow; E–DT: deceleration time of the E wave; e′: peak early diastolic velocity of the mitral annulus; E/e′: ratio of the E wave of the mitral flow and e′ of the mitral annulus; S: peak systolic velocity of the mitral annulus; LV GLS: global longitudinal strain of the left ventricle. Table 4. Cut-off values of interleukin-6 and values of the validation criteria for differentiation between the controls and women with pre-eclampsia and gestational hypertension Group Cut off (pg/ml) Sensitivity (%) Specificity (%) Positive predictive value (%) Negative predictive value (%) Accuracy (%) GH ≥ 4 56 72 59 69 65 PE ≥ 2.82 73 64 60 76 68 GH: gestational hypertension; PE: pre-eclampsia. 1 – Specificity 0.0 0.2 0.4 0.6 0.8 1.0 Sensitivity 1.0 0.8 0.6 0.4 0.2 0.0 Fig. 3. ROC curve for interleukin-6 (AUC = 0.67, р = 0.001) for determining the cut-off value for differentiating between the controls and the combined hypertensive groups (gestational hypertension + pre-eclampsia).
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