CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 6, November/December 2022 AFRICA 301 Cut-off levels for pre-operative ESR and first postoperative day ESR were 9.5 and 31.5 mm/h, respectively. The AUC values for pre-operative ESR and first postoperative day ESR were 0.73 (95% CI: 0.69–0.77, p = 0.0001) and 0.80 (95% CI: 0.75–0.84, p = 0.0001), respectively. The sensitivity and specificity of the pre-operative ESR cut-off value were 69.0 and 68.5%, respectively. The sensitivity and specificity of the first postoperative day ESR cut-off value were 76.5 and 75.6%, respectively. The pre-operative MPV and first postoperative day NLR to predict POD were determined by ROC curve analysis (Fig. 3). Cut-off levels for pre-operative MPV and first postoperative day NLR were 8.45 and 4.33 fl, respectively. The AUC values for pre-operative MPV and first postoperative day NLR were 0.78 (95% CI: 0.74–0.82, p = 0.0001) and 0.88 (95% CI: 0.85–0.91, p = 0.0001), respectively. The sensitivity and specificity of the pre-operative MPV cut-off value were 73.8 and 70.0%, respectively. The sensitivity and specificity of the first postoperative day NLR cut-off value were 79.1 and 79.3%, respectively. Discussion In this study we observed that pre- and postoperative inflammatory parameters including CRP, MPV and ESR levels, and PLR and NLR were significantly elevated in patients with POD. Increased APACHE II score was also associated with the presence of POD. Pre-operative PLR, ESR and MPV values and postoperative PLR, NLR and ESR values were independent predictors of POD in logistic regression analysis. POD was also associated with prolonged ICU stay and total duration of hospitalisation. Delirium is a common complication following CABG surgery, accounting for 32 to 73% of the cases.17 The pathophysiology of delirium following CABG surgery is complex and multiple factors affect its occurrence.18 Cholinergic deficiency is one of the hypotheses that has been associated with POD and cognitive dysfunction. Decreased level of cholinergic neurotransmitters in the central nervous system leads to neurotransmitter imbalance, Table 7. Univariate and multivariate regression analysis of operative and postoperative risk factors for postoperative delirium Variables Postoperative delirium Unadjusted OR (95% CI) p-value R2 Adjusted OR (95% CI) p-value Postoperative first day CRP 1.16 (1.12–1.20) 0.0001 0.13 1.04 (0.97–1.11) 0.30 Postoperative first day MPV 3.86 (2.96–5.03) 0.0001 0.16 1.35 (0.80–2.29) 0.26 Postoperative first day ESR 1.07 (1.06–1.08) 0.0001 0.24 1.07 (1.04–1.10) 0.0001 Postoperative first day PLR 1.09 (1.08–1.10) 0.0001 0.37 1.06 (1.03–1.09) 0.0001 Postoperative first day NLR 5.64 (4.30–7.39) 0.0001 0.33 2.72 (1.77–4.19) 0.0001 Postoperative first day lymphocytes 0.97 (0.89–1.05) 0.39 – – Aortic cross-clamp time 0.99 (0.98–1.01) 0.51 – – Number of anastomoses 0.98 (0.83–1.16) 0.82 – – CPB time 1.01 (0.99–1.02) 0.41 – – Intubation time 0.96 (0.88–1.025 0.39 – – Use of blood products 0.83 (0.59–1.05) 0.30 – – Use of inotropic support 1.22 (0.63–2.37) 0.55 – – APACHE II scores 2.13 (1.91–2.38) 0.0001 0.37 1.93 (1.61–2.33) 0.0001 Amount of drainage 1.00 (0.99–1.01) 0.98 – – CPB: cardiopulmonary bypass; MPV: mean platelet volume; CRP: C-reactive protein; PLR: platelet-to-lymphocyte ratio; NLR: neutrophil-to-lymphocyte ratio; ESR: erythrocyte sedimentation rate. Pre-operative MPV Postoperative NLR Reference line Sensitivity 1.0 0.8 0.6 0.4 0.2 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1 – Specificity Fig. 3. ROC curve analysis of pre- MPV and postoperative NLR to predict postoperative delirium Table 6. Univariate and multivariate regression analysis of pre-operative risk factors for postoperative delirium Variables Postoperative delirium Unadjusted OR (95% CI) p-value R2 Adjusted OR (95% CI) p-value Male gender 1.11 (0.76–1.63) 0.59 – – Age 0.99 (0.94–1.424 0.87 – – Ejection fraction 0.24 (0.19–0.29) 0.47 – – Diabetes mellitus 0.87 (0.62–1.24) 0.45 – – Hypertension 0.80 (0.55–1.14) 0.21 – – Hyperlipidaemia 1.01 (0.72–1.41) 0.97 – – Smoking 0.96 (0.68–1.36) 0.84 – – EuroSCORE 0.98 (0.88–1.08) 0.64 – – Basal heart rate 1.01 (0.98–1.03) 0.95 – – Pre-operative creatinine 1.31 (0.72–2.42) 0.38 – – Pre-operative platelets 1.00 (0.99–1.01) 0.73 – – Pre-operative lymphocytes 0.96 (0.91–1.01) 0.69 – – Pre-operative CRP 3.82 (2.74–5.33) 0.0001 0.11 1.12 (0.62–2.03) 0.72 Pre-operative haemoglobin 1.04 (0.91–1.19) 0.61 – – – Pre-operative MPV 6.77 (4.74–9.67) 0.0001 0.18 3.82 (1.98–7.38) 0.0001 Pre-operative leucocyte 1.01 (0.98–1.03) 0.43 – – – Pre-operative ESR 1.21 (1.16–1.26) 0.0001 0.12 1.15 (1.05–1.25) 0.002 Pre-operative PLR 1.12 (1.10–1.14) 0.0001 0.24 1.04 (1.01–1.08) 0.013 Pre-operative NLR 4.79 (3.62–6.34) 0.0001 0.20 1.27 (0.71–2.27) 0.42 MPV: mean platelet volume; CRP: C-reactive protein; PLR: platelet-to-lymphocyte ratio; NLR: neutrophil-to-lymphocyte ratio; ESR: erythrocyte sedimentation rate.
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