[Relationship between D-dimer concentration and inflammatory factors or organ function in patients with coronavirus disease 2019].

Objective: To explore the relationship between D-dimer concentration and inflammatory factors or organ function in patients with coronavirus disease 2019 (COVID-19).

Methods: A retrospective study was conducted. The clinical data of 72 patients with COVID-19 admitted to intensive unit of Tongji Guanggu Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology in Wuhan, Hubei Province from February 10th to 29th in 2020 were collected, including their general information, routine blood test, coagulation function, inflammatory parameters, cytokines, and organ function related laboratory parameters at admission. The patients were divided into two groups, namely D-dimer normal group (< 0.5 mg/L) and D-dimer elevated group (≥ 0.5 mg/L). The differences of general data, inflammatory parameters and cytokines between the two groups were compared. Besides, the correlation between D-dimer and organ function was analyzed by linear regression. The change in sequential organ failure assessment (SOFA) between the first visit after the onset of the disease and admission to intensive unit ≥ 2 was defined as being combined with organ damage. Receiver operating characteristic (ROC) curve was drawn to evaluate the predictive value of D-dimer on organ damage in patients with COVID-19.

Results: 65.3% of the 72 patients had abnormal coagulation. The D-dimer level of COVID-19 patients gradually increased with the aggravation of the disease, and the levels of ordinary type (n = 14), severe type (n = 49), and critical type (n = 9) were 0.43 (0.22, 0.89), 0.66 (0.26, 1.36), and 2.65 (0.68, 15.45) mg/L, respectively, with statistically significant difference (P < 0.05). Thirty-two patients (44.4%) had normal D-dimer, and 40 (55.6%) had elevated D-dimer. Compared with the normal D-dimer group, the patients in the D-dimer elevated group were older (years old: 67.7±11.6 vs. 54.0±13.1), and the levels of white blood cell count (WBC), neutrophil count (NEU), procalcitonin (PCT), high-sensitivity C-reactive protein (hs-CRP), interleukins (IL-6, IL-8, IL-10), IL-2 receptor (IL-2R) and tumor necrosis factor-α (TNF-α) at admission were significantly higher [WBC (×10/L): 7.16 (5.55, 9.75) vs. 5.25 (4.59, 6.98), NEU (×10/L): 7.11±5.46 vs. 3.33±1.58, PCT (μg/L): 0.08 (0.06, 0.21) vs. 0.05 (0.04, 0.06), hs-CRP (mg/L): 27.9 (3.4, 58.8) vs. 1.3 (0.8, 6.6), IL-6 (ng/L): 11.80 (2.97, 30.61) vs. 1.98 (1.50, 4.73), IL-8 (ng/L): 19.90 (13.33, 42.28) vs. 9.40 (12.35, 15.30), IL-10 (ng/L): 5.00 (5.00, 8.38) vs. 5.00 (5.00, 5.00), IL-2R (kU/L): 907.90±458.42 vs. 572.13±274.55, TNF-α (ng/L): 10.94±5.95 vs. 7.77±3.67], while lymphocyte (LYM) and monocyte (MON) counts were lower [LYM (×10/L): 1.14±0.49 vs. 1.46±0.42, MON (×10/L): 0.63±0.25 vs. 0.87±0.21], with significant differences (all P < 0.05). Linear regression analysis showed that D-dimer level was negatively related with pulse oxygen saturation (SpO), oxygenation index (PaO/FiO) and platelet count (PLT) with β values of -0.493, -11.615, and -0.018, respectively (all P < 0.05). However, D-dimer level was positively related with respiratory rate (RR), aspartate aminotransferase (AST), total bilirubin (TBil) and direct bilirubin (DBil) with β values of 0.485, 0.107, 0.291, and 0.404 (all P < 0.05). ROC curve analysis showed that the area under ROC curve (AUC) of D-dimer for predicting organ injury in COVID-19 patients was 0.889, and the 95% confidence interval (95%CI) was 0.753-1.000. When the optimal cut-off value was 2.36 mg/L, the sensitivity was 85.7%, and the specificity was 78.1%.

Conclusions: D-dimer levels in COVID-19 patients are correlated with inflammatory factors and organ function, and it can be used to predict organ injury.