Results
A total of 749 patients who were brought to the emergency department with suspected COVID-19 within the period from March to September 2020 and who had a positive PCR test result were identified. Of these 749 patients, 11 were excluded from the study because they sought hospital discharge against medical advice, 8 because they were referred to another hospital, 13 because they had no result of at least one of the d-dimer, fibrinogen and albumin parameters. The remaining 717 patients were included in the study.
Of the 717 patients who were included in the study, 371(51.7%) were male, their median age was 64 years (50–74), and their median length of hospital stay was 9 days (5–14). The median d-dimer, fibrinogen, albumin, DAR, FAR values were found to be 223(130–454) ng/ml, 419(324–534) mg/dl, 4.05(3.68–4.42) g/dl, 56(30.43–119.69) and 104.3(77.46–138.88), respectively. A total of 495 patients (69%) had at least one comorbidity in their medical history, and the most frequent comorbidity was hypertension (260 patients, 36.3%). A total of 550 patients (76.7%) were hospitalized in the ward unit, and 167(23.3%) were admitted to the ICU. In-hospital mortality occurred in 126 patients (17.6%) and did not occur in 591(76.7%). Table 1 shows the detailed data of the cases.
The median d-dimer value in the non-survivor group was significantly higher than that in the survivor group (non-survivor: 471ng/ml [264–869]; survivor: 184 mg/dl [116.5–364]; p<0.001). As for the median fibrinogen value, that in the non-survivor group was significantly higher than that in the survivor group (non-survivor: 474 mg/dl [388–577]; survivor: 403 mg/dl [315–514.5]; p<0.001). For the median albumin value, that in the non-survivor group was significantly lower than that in the survivor group (non-survivor: 3.6 g/dl [3.31–3.95]; survivor: 4.16 g/dl [3.79–4.48]; p<0.001). For the median DAR value, that in the non-survivor group was significantly higher than that in the survivor group (non-survivor: 127.79 [75.5–240.2]; survivor: 47.8 [27.29–94.47]; p<0.001). For the median FAR value, that in the non-survivor group was significantly higher than that in the survivor group (non-survivor: 133.49 [108.27–161.18]; survivor: 98.12 [73.56–131.84]; p<0.001). Table 2 shows the detailed intragroup comparisons by in-hospital mortality.
We performed ROC analysis to determine the in-hospital COVID-19 mortality predictive power of the d-dimer, fibrinogen, albumin, DAR and FAR levels. The AUC value of the d-dimer level was found to be 0.757 (Figure 1), and 74.6% sensitivity, 67.3% specificity, 32.8% positive predictive value (PPD), and 92.6% negative predictive value (NPD) were reached with the cut-off d-dimer value of 292.5 ng/ml. The AUC value of the fibrinogen level was found to be 0.637 (Figure 1), and 68.3% sensitivity, 56.5% specificity, 25.1% positive predictive value (PPD), and 89.3% negative predictive value (NPD) were reached with the cut-off fibrinogen value of 423 mg/dl. As for the albumin level, its AUC value was found to be 0.766 (Figure 1), and 81% sensitivity, 59.4% specificity, 29.8% PPD, and 93.6% NPD were reached with the cut-off albumin value of 4.015 g/dl. For DAR, its AUC value was found to be 0.773 (Figure 1), and 84.9% sensitivity, 58.4% specificity, 30.3% PPD, and 94.8% NPD were reached with the cut-off DAR value of 56.36. For FAR, its AUC value was found to be 0.703 (Figure 1), and 71.4% sensitivity, 64% specificity, 29.7% PPD, and 91.3% NPD were reached with the cut-off FAR value of 112.33. The detailed results of the ROC analysis are given in Table 3.
In terms of predicting in-hospital COVID-19 mortality, the patients with d-dimer>292.5 ng/ml had an odds ratio of 6.058; those with fibrinogen>423 mg/dl had an odds ratio of 2.794; those with albumin<4.015 g/dl had an odds ratio of 6.216; those with DAR>56.36 had an odds ratio of 7.898; and those with FAR>112.33 had an odds ratio of 4.437. In addition; patients with concurrent DAR>56.36 and FAR>112.33 had an odds ratio of 21.879 referring to patients with concurrent DAR<56.36 and FAR<112.33. The detailed odds ratio results are given in Table 4.