CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 1, January–April 2023 6 AFRICA Our study shows that a higher D-dimer threshold (5.69 mg/dl) gives a better sensitivity and specificity to predict PE in patients with COVID-19 who need oxygen support. The main features of COVID-19 patients with PE have been described in several studies.16-18 The patient characteristics reported in this study confirmed that male gender and longer delay from onset of symptoms to hospitalisation were associated with an increased risk of PE. Also, the patients were younger. The traditional risk factors of PE, as previously described, were not associated with the occurrence of PE in our study. There is no consensus in the world on the D-dimer cut-off point to suspect PE in COVID-19 patients. The International Society of Thrombosis and Hemostasis considered that a three- to four-fold increase in D-dimer concentration may be significant in terms of guidance for recognition and management of coagulopathy in COVID-19.19 This cut-off value differs slightly between studies. In the study of Mouhat et al., workers found that a D-dimer concentration greater than 2 590 ng/ml conferred a 17-fold increase in the risk of PE in 162 hospitalised patients with COVID-19 pneumonitis, with a resultant sensitivity of 83.3% and specificity of 83.8%.20 Ventura-Diaz et al. placed this threshold at 2 903 ng/ml (resultant sensitivity 81%) in their retrospective cohort of 242 hospitalised patients with COVID19, with a PE prevalence of 30%.21 In another study a total of 193 patients underwent CTPA 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. 1. ROC curve to determine the optimal threshold for D-dimer to predict PE occurrence on CTPA in patients with COVID-19 receiving thromboprophylaxis (AUC: 0.753; p = 0.007; 95% CI: 0.593–0.912; 64% sensitivity; 62.5% specificity; D-dimer = 5.69 mg/dl). Table 2. Clinical characteristics of the patients Characteristics Mean ± SD or n (%) Intensive care unit admission 5 (12.2) Length of stay in intensive care unit (days) 9 (12.5) Length of stay hospital (days) 9 (6.5) Mortality in hospital 0 Duration between CT and swab (days) 13.28 ± 7.69 Rhythm SR 40 (97.6) AF 1 (2.4) Need for oxygen support 25 (61) Systolic blood pressure (mmHg) 124.75 ± 17.66 Diastolic blood pressure (mmHg) 76.04 ± 10.95 Haemoptysis 2 (4.9) CHA2DS2-VASc 1.3 ± 1.5 Geneva score 4.31 ± 1.58 Class of Geneva score Low 13 (31.7) Intermediate 25 (61) High 3 (7.3) PESI score 72.48 ± 24.62 Class of PESI score Class I 18 (43.9) Class II 9 (22) Class III 11 (26.8) Class IV 2 (4.6) Class V 1 (2.4) Under anticoagulant therapy 25 (61) No thromboprophlaxis 16 (39) DVT thromboprophylaxis dose 14 (34.1) Modified thromboprophylaxis dose 2 (4.9) Full thromboprphylaxis dose 9 (22) Deep venous thrombosis 4 (9.8) AF: atrial fibrillation; CT: computed tomography; DVT: deep venous thrombosis; PESI: pulmonary embolism severity index; SR: sinus rhythm; AF: atrial fibrillation; CHA2DS2-VASc: congestive heart failure, hypertension, age > 75 years, diabetes mellitus, stroke, vascular disease, age 65–75 years, sex category. Table 3. Anticoagulant dosage according to severity of COVID-19 pneumonia in patients Anticoagulant dosage Severity of pneumonia Stage 1–2 Stage 3–5 No thromboprophlaxy 6 (50) 10 (34.5) DVT thromboprophylaxis dose 2 (16.7) 12 (41.4) Modified thromboprophylaxis dose 0 (0) 2 (6.9) Full thromboprphylaxis dose 4 (33.3) 5 ( 17.2) DVT: deep venous thrombosis. Table 4. Correlation analysis between D-dimer and some laboratory parameters and clinical scores Parameters 1 2 3 4 5 6 7 CHA2DS2-VASc R p 1 . PESI score R 0.484 1 p 0.001 Geneva score R 0.078 0.273 1 p 0.628 0.084 Qanadli score R 0.078 0.091 0.327 1 p 0.628 0.570 0.037 RV/LV ratio R 0.203 0.015 0.199 0.427 1 p 0.204 0.924 0.213 0.005 C-reactive protein R p 0.098 0.546 0.180 0.266 0.082 0.616 0.029 0.857 0.045 0.784 1 D-dimer R 0.200 0.259 0.108 0.067 0.084 0.197 1 p 0.211 0.102 0.500 0.677 0.600 0.222 CHA2DS2-VASc: congestive heart failure, hypertension, age > 75 years, diabetes mellitus, stroke, vascular disease, age 65–75 years, sex category; LV: left ventricle; RV: right ventricle.
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