key: cord-0885762-8ek694p3
authors: Zhu, Zhe; Cai, Ting; Fan, Lingyan; Lou, Kehong; Hua, Xin; Huang, Zuoan; Gao, Guosheng
title: Clinical value of immune-inflammatory parameters to assess the severity of coronavirus disease 2019
date: 2020-04-22
journal: International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases
DOI: 10.1016/j.ijid.2020.04.041
sha: 209b6403a23d6eebc8169aeab6c3da2ba3b9f72d
doc_id: 885762
cord_uid: 8ek694p3

Abstract Objective To explore the clinical value of immune-inflammatory markers to assess the severity of coronavirus disease 2019 (COVID-19). Methods 127 consecutive hospitalized patients with confirmed COVID-19 were enrolled in this study, and classified into non-severe and severe groups. Demographics, symptoms, underlying diseases and laboratory data were collected and assessed for predictive value. Results Of 127 COVID-19 patients, 16 cases (12.60%) were classified into the severe group. High level of interleukin-6 (IL-6), C-reaction protein (CRP) and hypertension were independent risk factors for the severity of COVID-19. The risk model based on IL-6, CRP and hypertension had the highest area under the receiver operator characteristic curve (AUROC). Additionally, the baseline IL-6 was positively correlated with other immune-inflammatory parameters and the dynamic change of IL-6 in the severe cases were parallel to the amelioration of the disease. Conclusion Our study showed that high level of IL-6, CRP and hypertension were independent risk factors for assessing the severity of COVID-19. The risk model established upon IL-6, CRP and hypertension had the highest predictability in this study. Besides, IL-6 played a pivotal role in the severity of COVID-19 and had a potential value for monitoring the process of severe cases.

Since December 2019, an unexperienced pneumonia emerged in Wuhan, China, and soon spread globally (Guo et al., 2020 , Wu et al., 2020 . This pneumonia was verified to be caused by a novel coronavirus and named as coronavirus disease 2019 by the World Health Organization (WHO). Based on phylogeny, taxonomy and established practice, this novel coronavirus was designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the Coronavirus Study Group (CSG) (Gorbalenya et al., 2020) . Similar to the former two pathogenic coronaviruses, severe acute respiratory syndrome coronavirus (SARS-CoV) and

Middle East respiratory syndrome coronavirus (MERS-CoV) at the beginning of the 21st century (Cui et al., 2019) , SARS-CoV-2 is likely originated from bat (Zhou Peng et al., 2020) , have the ability to spread from person to person (Chan et al., 2020) , cause pneumonia and severe respiratory syndrome (Chen N. et al., 2020) with a typic An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice. Regardless of most COVID-19 patients are mild, patients with severe type may quickly progress to acute respiratory distress syndrome (ARDS), multiple organ failure (MOF) and even death (Wang Y. et al., 2020) . Therefore, exploring potential risk factors for the severity of COVID-19 is crucial for delay or halt the progression of the disease. Previous studies have revealed that patients with old age and underlying diseases are more likely to be aggravated (Wang D. et al., 2020 , Wang Z. et al., 2020 , and aberrant immune-inflammatory response and cytokine storm may played an important role in the disease progression (Zhou Yonggang et al., 2020) .

Therefore, a retrospective study was performed to compare the clinical features, immune-inflammatory parameters and cytokines between the severe and non-severe groups, and tried to establish a predict model for assessing the severe cases in Hwa PJ-NBEY-KY-2020-061-01), and a written informed consent was obtained from all enrolled patients.

Throat-swab, nasopharynx-swab and sputum specimens from all suspected SARS-CoV-2 infection patients were collected, and SARS-CoV-2 RNA was detected Table 2 showed the baseline laboratory parameters of included patients.

Neutrophil%, neutrophil-to-lymphocyte ratio (NLR), fibrinogen, sialic acid (SA), C-reaction protein (CRP), IL-6, interleukin-10 (IL-10) and interferon-γ (IFN-γ) in the severe group were significantly higher than those in the non-severe group (P<0.05).

While lymphocyte%, lymphocyte count and platelet count were significantly lower in the severe group when compared with the non-severe group (P<0.05). There were no significant differences in cTnI and NT-proBNP between the severe and non-severe groups. As for the arterial blood gas parameters, higher levels of pO 2 and pCO 2 were found in the non-severe group (P<0.05), while pH and lactate showed no differences between the two groups.

The result of multivariate logistic regression analysis demonstrated that the high level of peripheral blood cytokine IL-6, CRP and hypertension were independent risk factors for assessing the severity of COVID-19, with odd ratios ( Figure 1 ).

The baseline IL-6 was positively correlated with neutrophil% (r=0.398, 

The dynamic changes of IL-6 were analyzed in 45 non-severe cases and 12 severe cases. The level of IL-6 in the severe group was significantly higher than non-severe group at baseline and 5-10 days after disease onset, but dropped gradually day-by-day, and reached a level equal to non-severe group at ≥ 10 days after An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice. 

This study was performed at Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, a largest local designated hospital treating COVID-19. Different from Wuhan, all patients treated immediately once relative symptoms appeared. The time interval from illness onset to hospitalization was 5.35±3.72 days, most of them (87.40%) were non-severe cases. Therefore, it may sever as a representative of the general situation, except for the severely affected area. We found higher age, BMI index and proportion of hypertension, highest temperature>39 , chest distress and dyspnea in the severe group, but nausea was more often in non-severe group. We also observed significant increases of neutrophil%, NLR, fibrinogen, SA, CRP, IL-6, IL-10, IFN-γ, pO 2 and pCO 2 and decreases of lymphocyte%, lymphocyte count and platelet count in the severe group.

Previous studies have indicated that the severe and aberrant host immune response are responsible for the severity of COVID-19 (Zhou Yonggang et al., 2020).

Meanwhile, it was companied by a sharp change in the peripheral blood immune-inflammation parameters. Therefore, emerging studies were focus on these accessible laboratory data for assessing the severity of disease. The increased of neutrophil counts indicate the intensity of inflammatory response, while the decreased An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice.

J o u r n a l P r e -p r o o f 11 of lymphocyte counts suggest the damage of immune system, therefore, higher NLR maybe a potential maker for risk factor (Liu Jing et al., 2020) . Cytokines are small protein molecules aimed for cell-to-cell communications, and play an immunomodulating function (Chousterman et al., 2017) . However, in some infection diseases, excessive inflammation activate cytokine storm, lead to An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice. 12 serious pathological changes, even is responsible for multiorgan dysfunction (Liu et al., 2016) . Cytokine storm have been implicated in severe influenza (Liu et al., 2016) , SARS and MERS (Channappanavar and Perlman, 2017) , and evidence has revealed that cytokine storm may as a cause for deleterious consequence during SARS-COV-2 infection (Zhou Yonggang et al., 2020) . In consist with the previous studies (Liu Jing et al., 2020) , cytokine IL-6, IL-10 and IFN-γ in the severe group were significantly higher than those in the non-severe group, especially for IL-6, and it was recognized as an independent risk factor by using multivariate logistic regression analysis, with OR of 1.090 (95% CI: 1.040-1.147).

As mentioned above, IL-6 had the highest AUROC among the inflammation parameters in this study, so we further analyzed their correlations. It was found that IL-6 was significantly correlated with other inflammation parameters, and a most close relationship was observed between IL-6 and IL-10 (r=0.638, P<0.001). IL-10 is an anti-inflammatory cytokine, the increased of IL-10 maybe reflect a self-protection during cytokine storm, the level of IL-10 was also directly related to the degree of inflammation (Chousterman et al., 2017) , and high IL-10 was associated with immunosuppression in sepsis (Hotchkiss et al., 2013) .

IL-6 plays a key role in cytokine storm owing to its pleiotropic property (Gupta et al., 2020) . Apart from its robust proinflammatory function, it induces a variety of In line with prior studies, our study also demonstrated that severe cases were older and more likely to have underlying diseases (Wang D. et al., 2020 , Wang Z. et al., 2020 . However, apart from hypertension, the number of patients with and without diabetes, cardiovascular disease, hepatic disease, chronic lung disease and cancer An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice.

14 showed no differences in non-severe and severe groups. Low number of patients in these underlying diseases may cause certain bias, while a relatively large number in hypertension is sufficient to make a certain comparison. Additionally, the level of IL-6 in patients with hypertension was higher than those without hypertension in this study, demonstrated a severe inflammation lesion in the hypertension patients. Hypertension patients are always associated with immune activation, resulted in immune system impaired (Norlander et al., 2018) . Therefore, we speculated that the abnormal immune function of hypertension patients may played a role in the COVID-19 progression.

Intriguingly, angiotensin-converting enzyme 2 (ACE-2) played a protect role in hypertension (Povlsen et al., 2020) , while SARS-COV-2 use ACE-2 to enter target cells, and may reduce ACE-2 expression just like SARS-COV do (Kuba et al., 2005) , which was likely to carry a burden to those weakness patients and aggravate the disease eventually. In this study, the existing of hypertension severed as an independent risk factor for the severity of COVID-19, it reminded us to take specially care of these high-risk patients to prevent the development of disease.

cTnI and NT-proBNP are two biomarkers for cardiac dysfunction. The baseline level of cTnI in the most patients with COVID-19 was below 0.03 ng/ml, no significant difference was found between the severe and non-severe groups, so did the level of NT-proBNP. It was consistent with the study by Peng et al., in which tests were performed on admission (Peng et al., 2020) . However, Chen et al. found the elevated cTnI and NT-proBNP during hospitalization were significantly correlated with the critical disease status (Chen Chen et al., 2020) . Unfortunately, we did not test An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice.

J o u r n a l P r e -p r o o f 15 these two markers dynamically, the value of them deserve further investigation.

A blood gas analysis can measures the level of oxygen, carbon dioxide, lactate and pH in the blood, which is helpful to show how well the lungs are working. A previous study has indicated that higher level of lactate and lower levels of pO 2 and pCO 2 were found in the death patients with COVID-19 (Peng et al., 2020) . The present study also showed lower levels of pO 2 and pCO 2 in the severe group, but pH and lactate showed no differences between the two groups. However, only few patients in the non-severe group performed blood gas analyses and partial patients received oxygen therapy before blood gas analysis, thus making it difficult to explore their role in the present study.

However, this study has some limitations. First, IL-6 is not a routine laboratory test, which would limit its usage. Second, the sample size included in this study is relatively small, especially of those in severe group. Third, it is a retrospective single-center study, the effectiveness of this model has not been validated by us and others. Forth, some laboratory analyses (e.g. blood gas analysis) were performed on partial patients. Therefore, a prospective multi-center study with a larger sample size is warranted.

Our study demonstrated that high level of peripheral blood cytokine IL-6, CRP and the existence of hypertension were independent risk factors for assessing the severity of COVID-19. The risk model established upon IL-6, CRP and hypertension An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice. 

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