The cohort included in this study consisted of 156 hospitalized patients diagnosed with COVID-19 pneumonia and 20 healthy controls. Among all patients, 56 died during hospitalization and 100 were successfully discharged. The median age of all enrolled patients was 66 years (IQR, 46.3-73.0; range, 9-99 years), and 76 (48.7%) were male. Comorbidities were identified in 101 (64.7%) patients, with hypertension, cardiovascular disease, and diabetes being the most common ones. The most common symptoms presented upon admission were fever (79 [50.6%]) and cough (71 [45.5%]), followed by dyspnea (28 [17.9%]) and fatigue (23 [14.7%]) (Table 1).
Compared with successfully discharged patients, the patients who died during hospitalization were older (72.0 years [65.3-83.0] VS 58.0 years [37.0-69.0]), and were more likely complicated with underlying diseases such as hypertension (34 [60.7%] vs 31 [31.0%]), diabetes (20 [35.7%] vs 11 [11.0%]), cardiovascular disease (27 [48.2%] vs 17 [17.0%]), cerebrovascular disease (13 [23.2%] vs 9 [9.0%]), chronic obstructive pulmonary disease (COPD) (15 [26.8%] vs 12 [12.0%]), cancer (11 [19.6%] vs 3 [3.0%]), chronic renal disease (11 [19.6%] vs 4 [4.0%]), and chronic liver disease (12 [21.4%] vs 2 [2.0%]). Compared with survivors, non-survivors were more likely to present with fatigue (15 [26.8%] vs 8 [8.0%]), anorexia (9 [16.1%] vs 4 [4.0%]), and neuropsychic symptoms (4 [7.1%] vs 0) (Table 1).
In terms of laboratory tests, multiple differences between survivors and non-survivors were identified and summarized in Table 2. Specifically, non-survivors had an increased level of white blood cell (WBC) count, neutrophil count, percentage of neutrophils, D-dimer, creatinine, creatine kinase (CK), and lactate dehydrogenase (LDH), as well as higher levels of c-reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6). Whereas, percentage of lymphocytes, platelet count, and albumin levels were significantly lower in non-survivors. In addition, non-survivors had elevated levels of lactate and glucose, accompanied by lower levels of PaO2/FiO2 (Table 3). Furthermore, our result suggested that the level of LYM (%) in COVID-19 patients upon admission was significantly lower than that in the control group. In contrast, the levels of CRP, D-dimer, and lactate were higher in COVID-19 patients (Table 4).
150 (96.2%) patients received antibiotics and 139 (89.1%) received antiviral treatment. Unsurprisingly, systematic corticosteroid was more commonly applied in non-survivors. 56 patients (35.9%) received high-flow nasal cannula oxygen therapy, 44 (28.2%) received non-invasive mechanical ventilation and 19 patients (12.2%) required invasive mechanical ventilation support. 6 patients (3.8%) received renal replacement therapy (RRT) and no patients were treated with extracorporeal membrane oxygenation therapy. Oxygen support (including high oxygen flow, noninvasive assisted ventilation, and mechanical ventilation) and renal replacement therapy was more commonly applied in non-survivors (Table 5).
The clinical outcomes of the enrolled 156 COVID-19 patients were summarized in Table 6. Unsurprisingly, non-survivor patients were more likely to develop complications compared with survivors. Respiratory failure was the most frequently developed complication (106 [67.9%]), followed by sepsis (103 [66.0%]), ARDS (67 [42.9%]), septic shock (50 [32.1%]), arrhythmia (42 [26.9%]), acute cardiac injury (26 [16.7%]), cardiac failure (24 [15.4%]), and acute kidney injury (18 [11.5%]). The median time from disease onset to admission was 10.0 days (IQR 4.3-16.0). And the median time from disease onset to discharge was 36.0 days (IQR 27.3-48.0), whereas the median time to death was 17.0 days (IQR 10.0-26.5). After comparing the time from disease onset to hospital admission and total hospital stay between non-survivors with survivors [(median time, 6.0 days [1.0-10.0] vs 14.5 days [7.0-20.0]) and (median time, 9.0 days [3.3-16.0] vs 22.0 days [16.0-29.0]) respectively], it seemed like the disease progressed more rapidly in non-survivors.
Next, multivariable logistic regression assay discovered that age (OR [odds ratio]=1.098, 95% CI [confidence interval]: 1.006-1.199, P=0.037), duration from onset to admission (OR=0.853, 95% CI: 0.750-0.969, P=0.015), LYM (%) at admission (OR=0.787, 95% CI: 0.686-0.903, P=0.001), and lactate at admission (OR=2.689, 95% CI: 1.044-6.926, P=0.040) were independent risk factors for in-hospital death of COVID-19 pneumonia (Table 7).
The Kaplan-Meier survival curve showed a trend toward poorer survival in COVID-19 patients with increased lactate levels and/or decreased LYM (%) upon admission (P=0.020 and P<0.001, respectively) (Fig. 1). In addition, we conducted the ROC curve assay and calculated the AUC among the following three indicators. We discovered that the AUC of LYM (%) was 0.903 (95% CI, 0.856-0.949), 0.792 (95% CI, 0.720-0.863) for D-dimer and of 0.651 (95% CI, 0.555-0.748) for lactate (Fig. 2). Comparing to the other indicators, the AUC of LYM (%) was higher in predicting in-hospital death (LYM [%] VS D-dimer, P=0.003; LYM [%] VS lactate, P<0.001; respectively). Furthermore, we discovered that the cutoff value of LYM (%) for predicting in-hospital death was 14.7%.