COVID-19 has spread in more than 100 countries up to late March, which is much more infectious and invasive than SARS and MERS[4]. The severe cases reached a peak of 11977 (16.1%) on Feb 18th and gradually decreased later in China according to data published by NHC. The total mortality 4.0% (March 26th) is much lower than SARS in 2003 and MERS in 2015[4]. However, the mortality in severe patients exceeded 60% in previous report[1]. In this single-center and retrospective study, we described and analyzed the demographic and clinical characteristics of 21 death cases with confirmed COVID-19 in EICU of Zhongnan Hospital of Wuhan University.
Males (71.4%) were major victims here in this study similar with other researches in different hospitals[1, 2, 5]. The mean age was 66 years with almost a half over 70 years. Combining with COVID-19 studies in other centers during the same period, older males seem more susceptible to SARS-CoV-2 infection and are the primary members in severe group with poor prognosis[1, 2, 5], which is supported by our data. Same findings were reported in previous SARS[7, 8] and MERS studies[9, 10]. We found overweight adults account for more than half in the study, which was ignored before. We should also pay attention that a few patients suffered self-healing diarrhea during the course. The mean time from illness onset to hospital admission was 5 days, less than 11 days presented in the research conducted in Jinyintan Hospital and Wuhan Pulmonary Hospital[2]. 20 patients had received oral or intravenous medication treatments before admission including antibiotic and antiviral therapy mostly. However, no drugs seemed effective to delay the progression of COVID-19 in the early stage of the epidemic.
In laboratory tests, reduced lymphocytes, a characteristic index in SARS-CoV-2 infection, were observed in majority patients in our study, which is also mentioned in many other reports[3, 11, 12]. We speculate the continuous lymphocyte proportion decrease may indicate excessive consumption by SARS-CoV-2 like the mechanism in SARS-CoV and MERS-CoV infection[13, 14]. Lymphopenia seemed more common in severe patients[2, 3]and might reflect the severity and higher mortality of COVID-19. Lymphocyte subpopulation was detected and both CD4-positive and CD8-positive T lymphocytes decreased significantly. Damage of T lymphocytes and inhibition of the cellular immune system may contribute great to the deterioration. Levels of serum IL-6 increased rapidly in a short period, which could be explained by the active inflammatory storm[5, 6]. In this study, we detected reduced platelets on admission and progressive decline during hospitalization, which were previously demonstrated to have a relation with severe inflammation[15, 16]. Urea and creatinine rose in different degrees represented renal dysfunction because of virus invasion, hypoxaemia, hypoperfusion or original kidney diseases. Coagulation dysfunction was observed in almost all cases marked by prolonged PTs and significant increased serum D-dimer concentrations.
Despite of many clinical assessment and prediction scores, there is no standard recommendation to predict the severity and risk of mortality for patient with viral pneumonia up to now. Viral pneumonia, including COVID-19, might progress rapidly to critical illness and develop to ARDS, multiple organ failure and even death. APACHE II scoring system has been widely used to assess patient severity and predict outcome in critical ill patients[17]. SOFA scoring has also been used to predict prognosis and assist the diagnosis of sepsis/septic shock in intensive care unit (ICU). In our study, the APACHE II and SOFA scores on admission were 14 ± 3 and 7 (5-8) respectively. The highest APACHE II and SOFA scores were 26 (22-32) and 14 (12-16), respectively. They both increased along with the progression of disease. The SOFA score was similar with the non-survivors at ICU admission in one study about COVID-19 critically ill patients[3, 6], however, the APACHE II score was similar with the survivors. Another study found that higher SOFA score at admission was associated with higher odds of death in COVID-19 patients[2]. This study did not present the APACHE II score in article. SOFA scores, including mean and highest SOFA scores, are both good predictors for prognosis. Independent of the initial score, an increase of SOFA score during the first 48 h predicts a mortality rate of 50% [18]. On the other hand, SOFA score is the diagnostic marker for sepsis/septic shock [19]. In our study, 18 (85.7%) of patients developed septic shock. As the study demonstrated that more than 50% of COVID-19 patients developed sepsis[2], which reminded us the possibility of virus induced sepsis syndrome besides SARS-CoV-2 infection combined bacterial infection. APACHE II score 10-20 suggests the mortality rate of about 50%, and above 20 suggests the mortality rate of about 80%. Although existing difference between studies aforementioned, we still considered that APACHE II score had its general predictability for outcome in COVID-19, which might be less sensitive enough than SOFA score.
In our study, we conducted two special scores to predict the probability of mortality in pneumonia, MuLBSTA[20] and PSI [21]. Both score results in our study showed that 13 (61.9%) patients had the high risk of mortality at admission. The highest scores increased to 15 (13-16) (MuLBSTA) and 163 (149-185) (PSI), respectively, accounting for 19 (90.5%) patients. Up to now, there is few research analyzing pneumonia special severity scoring system in SARS-CoV-2 infected pneumonia. One research about COVID-19 mortality analysis found that CURB-65 score was significantly higher in non-survival groups than survival groups[2]. Our study identified the usefulness of MuLBSTA and PSI scoring systems in predicting the risk of mortality in COVID-19. However, the accurate sensitivity and specificity of those pneumonia special severity scoring systems needs further research and verification.
All the death cases showed complications, mainly including ARDS (100%), septic shock (85.7%), acute kidney injury (81.0%), liver dysfunction (57.1%) and acute cardiac injury (33.3%), which had been also observed in similar researches[2, 5, 6]. The primary cause of progressive impact on multiorgan by SARS-CoV-2 is that the binding receptor for SARS-CoV-2, ACE2 mainly exists in blood vessels and lung alveolar type II (AT2) epithelial cells [22]. And ACE2 also exists in the heart, kidney, liver and so on. Thus, the viral infection may stimulate the immune cells to release pro-inflammatory cytokines and damage the target organs, even causing death.
The treatments for COVID-19 mainly covered anti-pathogen therapy, different kinds of oxygen therapy, glucocorticoid therapy, immunoglobulin therapy, and advanced life support for organ function, which were similar with published researches[2, 5, 6, 11]. 9 (42.9%) patients received low molecular heparin therapy in our study. During the treatment of the COVID-19 patients, coagulation abnormalities can be observed through laboratory findings mostly, including D-dimer, prothrombin time and so on, but not all the cases may develop to some detectable relative clinical manifestations. In a large retrospective cohort study about COVID-19, researchers found that elevated D-dimer, greater than 1μg/L, at admission was a risk factor for mortality in adult patients with COVID-19 [2]. The final impacts of coagulation abnormalities could be understood according to the lung biopsy conducted by Shenzhen Third People’s Hospital [23]. The whole lung tissue displayed a diffuse congestive appearance with variable degrees of hemorrhagic pulmonary infarction and microthrombosis formation prominently presented in outer edge of the lung. The biopsy also pointed out that hemorrhagic necrosis in the outer edge of the lung might be the origination of COVID-19 and one of the main causes of death in severe patients. Coagulation abnormalities can be observed in severe pneumonia and sepsis. In a study of community-acquired pneumonia, D-dimer had been found to elevate persistently in 86.5% of patients, even among the least ill cases[24]. The research about patients with infection or sepsis identified in the emergency department showed that high levels of D-dimer was associated with 28-day mortality[25]. These findings highlighted the complexity of the coagulation response to viral infection and corresponding coagulation-based therapeutics.