key: cord-0899568-fcgcittn
authors: Li, Huan; Xiang, Xiaochen; Ren, Hongwei; Xu, Lingli; Zhao, Lisha; Chen, Xiaoqiong; Long, Hui; Wang, Qiang; Wu, Qingming
title: SAA is a biomarker to distinguish the severity and prognosis of Coronavirus Disease 2019 (COVID-19)
date: 2020-04-08
journal: J Infect
DOI: 10.1016/j.jinf.2020.03.035
sha: efc44484071432110517cd562c108bc9b1137aa8
doc_id: 899568
cord_uid: fcgcittn

BACKGROUND: To explore the significance of SAA in evaluating the severity and prognosis of COVID-19. METHODS: A total of 132 patients with confirmed COVID-19 who were admitted to a designated COVID-19 hospital in Wuhan, China from January 18, 2020 to February 26, 2020 were collected. The dynamic changes of blood SAA, CRP, PCT, WBC, Lymphocyte (L), PLT, CT imaging, and disease progression were studied. All patients completed at least twice laboratory data collection and clinical condition assessment at three time points indicated for this study; The length of hospital stay was longer than 14 days prior to February 26, 2020. RESULTS: COVID-19 patients had significantly increased SAA and CRP levels, while L count decreased, and PCT, WBC, and PLT were in the normal range. As disease progressed from mild to critically severe, SAA and CRP gradually increased, while L decreased, and PLT, WBC, and PCT had no significant changes; ROC curve analysis suggests that SAA/L, CRP, SAA, and L count are valuable in evaluating the severity of COVID-19 and distinguishing critically ill patients from mild ones; Patients with SAA consistently trending down during the course of disease have better prognosis, compared with the patients with SAA continuously rising; The initial SAA level is positively correlated with the dynamic changes of the serial CT scans. Patient with higher initial SAA level are more likely to have poor CT imaging. CONCLUSIONS: SAA and L are sensitive indicators in evaluating the severity and prognosis of COVID-19. Monitoring dynamic changes of SAA, combined with CT imaging could be valuable in diagnosis and treatment of COVID-19.

COVID-19, recently broke out in Wuhan, China, has spread rapidly throughout China and other countries. This new type of coronavirus could cause severe acute respiratory syndrome and injuries in other systems as well. The disease progresses rapidly, leading to multiple organ failure and death 1 2 . Quite a few patients have no specific symptoms/signs or radiological abnormalities at the early stage, with only mild symptoms, making the early diagnosis of disease difficult. Therefore, early identification of the infection and creating effective treatment plan are particularly imperative 3 4 . A series of inflammation factors, such as serum amyloid A (SAA), Creactive protein (CRP), procalcitonin (PCT), white blood cells (WBC), lymphocyte (L) and platelet (PLT) have been used in clinic as inflammation indicators. In this research, the authors want to explore if these factors can also assist in the diagnosis of COVID-19 infection and estimate of the disease severity. Thus, in this research, the authors systematically studied the dynamic changes of above inflammation indicators in patients infected with COVID-19, in order to evaluate their clinical values in predicting the severity and prognosis of COVID-19.

We conducted a retrospective study focusing on the significance of SAA in evaluating the severity and prognosis of COVID-19. A total of 132 patients with COVID-19 were collected from Tianyou Hospital of Wuhan University of Science and Technology, from January 18, 2020 to February 26, 2020. Tianyou Hospital, Wuhan University of Science and Technology, located in Wuhan, Hubei Province, the endemic areas of COVID-19, is one of the major tertiary teaching hospitals and is responsible for the treatments for COVID-19 assigned by the government. All patients were tested positive with SARS-CoV-2 and hospitalized. Patients completed at least twice laboratory data collection and clinical condition assessment at three time points indicated for this study. The length of hospital stay was longer than 14 days prior to February 26, 2020.

The dynamic changes of blood SAA, CRP, PCT, WBC, Lymphocyte (L), PLT, CT imaging, and disease progression were studied. At the same time, clinical conditions were evaluated and CT scans were obtained. Data were collected at three time points: admission, 3-5 days of hospitalization, and at the composite endpoint. Composite endpoint is February 26, 2020.As of February 26, 2020, the number of hospital discharge, inpatients, and the number of dead were counted.

We extracted the medical records of patients and sent these to the data collection center of (2) At room air, SpO 2 lower than 93%;

(3) The partial pressure of Arterial blood oxygen (PaO 2 )/the fraction of inspired oxygen (FiO 2 ) ≤ 300mmHg;

(4) CT chest imaging shows that lung damage develops significantly within 24 to 48 hours.

Critically severe: Meet any of the following (1) Respiratory failure requiring mechanical ventilation;

(2) Signs of septic shock;

(3) Multiple organ failure requiring ICU admission.

2) CT imaging classification: the imaging was classified into four types of normal, mild, progressive, and severe, with scored at 0, 1, 2, and 3, respectively.

(1) Mild: the main manifestations are ground-glass opacities and consolidation. Some cases show very thin, small patchy subpleural ground-glass opacities or ground-glass nodules. Lesions can be single or multiple, and both lung lobes can be involved. Lesions are more common in the middle and lower lobes, and mostly distributed in the outer zones of the lung and subpleural areas.

(2) Progressive: large lesions can be seen and multiple lung lobes in both lungs can be involved.

Consolidation and fibrosis of varying sizes are often seen within the lesions. Some cases may be accompanied by bronchial retraction, bronchiectasis, and interlobular pleural thickening.

However, pleural effusion and enlarged mediastinal lymph nodes are rare in this type.

(3) Severe: Lesions are diffuse in both lungs and uneven in density. Large areas of consolidation and ground-glass opacities can be seen. The sign of -white lung‖ can be seen due to large areas of the lung are involved. The interlobular pleura and bilateral pleura are usually thickened, and pleural effusion can be seen.

3) Outcome of illness: According to clinical progression, cases were divided into four types: fully recovered, improved, exacerbation, and death.

Statistical analysis was performed using SPSS 25.0 software. Kruskal-Wallis H-test and independent sample chi-square test were used to analyze differences between groups. Due to unequal variance, Tamhane 's T2 statistical method was a fair measure to perform multiple comparisons among groups of mild, moderate, severe, and critical severe patients for the value of SAA/L. Two-tailed P value less than 0.05 was considered statistically significant. The Receiver

Operating Characteristic curve (ROC curve) was used to calculate the area under the curve (AUC) of SAA, CRP, L, and SAA / L in order to evaluate the sensitivity and specificity of these factors. Spearman correlation coefficient was utilized to measure the degree of correlation between the hierarchically ordered variables in this study.

This was a retrospective case series study and no patients were involved in the study design, setting the research questions, or the outcome measures directly. No patients were asked to advise on interpretation or writing up of results.

From January 18, 2020 to February 26, 2020, 693 patients with COVID-19 was treated in Tianyou Hospital, and 132 patients met the requirements of this study. The patients were between 33-89 years old, with an average age of 62 years. And 87 of 132 patients were over 60 years, accounting for 65.9%. Of these patients, 75 were males, accounting for 56.8%, and 57 were females, accounting for 43.2%. (table 1) At the time of admission, 60 patients had mild or moderate symptoms, accounting for 45.5%; and 56 patients had severe symptoms, accounting for 42.4%. 16 of 132 patients were critically severe, accounting for 12.1%. In this study, more patients were male and more patients were more than 60 years, consistently with previous literature reports [3] . (table 1 According to the results showed in Table 2 , with disease progressing from mild to critically severe, SAA and CRP gradually increased, while L gradually decreased (P<0.05). However, PLT, WBC, and PCT were all within the normal ranges, suggesting that SAA, CRP, and L are closely related to disease classification, while WBC, PCT, and PLT are of little significance.

Due to unequal variance, Tamhane 's T2 statistical method was a fair measure to perform multiple comparisons among groups of mild, moderate, severe, and critical severe patients for the value of SAA/L. The SAA/L of severe/critically severe patients was significantly higher than that of mild/moderate ones, and p<0.01 indicates significant difference. (Fig 1) .

To detect if SAA/L is more sensitive in predicting the severity of disease, the authors used ROC curve analysis to calculate the area under the curve (AUC), regarding mild/moderate type as negative whereas severe/critical severe type as positive. The results showed that AUC from high to low was SAA1/L1 > CRP1 > SAA1 > L1, with the specific value at 0.748, 0.744, 0.718, and 0.700, respectively. Next, the authors used the method of Jordan Index to calculate the critical values of SAA/L that could be utilized as the reference for patient clinical classification (Fig 2) .

The dynamic changes of SAA, CRP, L, and SAA/L reflected the change of patient condition at 3-5 day-hospitalization. Patients with decreased SAA2, CRP2, SAA2/L2 and elevated L2 were more likely to have improved conditions (table 3) .

To detect if SAA2/L2 is more sensitive in predicting the progression of disease, the authors used To detect if SAA and L dynamic changes are valuable in predicting the patient outcome, the authors used ROC curve analysis to calculate the AUC of the difference of SAA, L, and SAA/L between the first and third time point, with the criteria of patient discharge as negative whereas patient death as positive. The results showed that AUC from high to low were L1-L3>SAA3-SAA1>SAA3/L3-SAA1/L1, with the specific value of 0.925，0.884, and 0.863, respectively( Fig   5) .

The CT imaging features were evaluated and scored as follows: normal (0 points), mild (1 point 

According to the correlation analysis showed in table 8, the first SAA level at admission was correlated with the dynamic changes of the first, second, and third CT scans. Specifically, for the patients with higher level of SAA1 at admission, the CT classification tended towards severe.

The correlation of the first SAA with the second CT result was higher than that with the first CT result, suggesting the significance of SAA in estimating the progression of disease was higher than CT scan alone (table 8) .

initial symptom is mild to moderate fever 3 5 . Some patients may have multiple systematic symptoms such as chills, malaise, respiratory distress, or gastroenterological disorders like nausea/vomiting. In some cases, the disease progresses rapidly and patients develop acute respiratory distress syndrome, septic shock, uncompensated acidosis, and coagulation dysfunction within a few days [5] [6] [7] [8] . The severity and prognosis of COVID-19 are complicated by the diversity of symptoms, imaging manifestations, and the degree of disease progression 8 9 .

Therefore, early diagnosis and appropriate treatment are essential in reducing the morbidity and mortality of COVID-19-infected patients.

Inflammatory factors, such as SAA, CRP, L, PCT, WBC, and PLT are frequently used to predict, diagnose, and evaluate many inflammatory diseases. SAA is a non-specific acute phase protein mainly produced by cytokines IL-1β, IL-6 and TNF-α in liver cells. As a marker of inflammation, its clinical value is obtaining more attention recently [10] [11] [12] . Studies report that patients with severe acute respiratory syndrome had significantly increased level of SAA, suggesting SAA could be used as a biomarker to monitor the progression of respiratory diseases 13 . SAA is able to promote inflammatory response through activating chemokine and inducing chemotaxis even at a very low concentration 14 15 SAA/L and elevated L had improved clinical conditions. In addition, the results showed that SAA levels continued to increase in exacerbating and deceased patients, whereas in patients who were discharged and well recovered, SAA fell below 3mg/L. The trend could be described as that patients with progressively decreased SAA are more likely to have a better prognosis than the patients who have continuously high level of SAA, suggesting a significant correlation between SAA dynamic change and prognosis. This phenomenon may be related to the activation of body's inflammation response, which stimulates liver cells to produce a large amount of SAA 20 21 .

CT imaging has been proved to be one of the most significant clinical diagnostic methods for COVID-19. According to the correlation analysis in this study, the first SAA level at admission was correlated with the dynamic changes of the first, second, and third CT scan. Specifically, for the patients with higher level of SAA, the CT classification tended towards severe. The correlation of the first SAA with the second CT result was higher than that with the first CT result, suggesting the value of SAA in estimating the progression of disease, especially when combined with serial CT scans during the course of disease.

This study also found that the ratio of SAA to L was more sensitive than SAA or L used alone, as SAA/L had the highest AUC in ROC analysis, compared with SAA and L. The authors found there was a significant statistical correlation of SAA/L with clinical classification and outcomes when using these critical values as a reference for patient categorization.

One limitation of this study lies in it was performed in a single medical facility, lacking the control group design due to the emergent situation of COVID-19 breakout. In the future, the researchers will collaborate with a few medical facilities in the area and design the control group to improve the reliability of the study.

Based on the study results, SAA alone or combined with L (SAA/L) could be used as a significant marker to indicate and track inflammation conditions in COVID-19 infected patients.

SAA and L are sensitive indicators in evaluating the severity and prognosis of COVID-19.

Monitoring dynamic changes of SAA, combined with CT imaging could be a valuable strategy in the diagnosis and treatment of COVID-19. 

Preliminary prediction of the basic reproduction number of the Wuhan novel coronavirus 2019-nCoV

A Novel Coronavirus from Patients with Pneumonia in China

Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review

The course of clinical diagnosis and treatment of a case infected with coronavirus disease 2019

Genomic characterization and epidemiology of 2019 novel coronavirus: implications of virus origins and receptor binding

Virus against virus: a potential treatment for 2019-nCov (SARS-CoV-2) and other RNA viruses

The Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. The epidemiological characteristics of an outbreak of 2019 novel coronavirus disease (COVID-19) -China

Clinical findings in a group of patients infected with the 2019 novel coronavirus (SARS-Cov-2) outside of Wuhan, China: retrospective case series

Clinical Characteristics of Coronavirus Disease 2019 in China

Human SR-BII mediates SAA uptake and contributes to SAA pro-inflammatory signaling in vitro and in vivo

Emerging functions of serum amyloid A in inflammation

Acute-phase serum amyloid A:an inflammatory adipokine and potential link between obesity and its metabolic complications

Protein Chip Array Profiling Analysis in Patients with Severe Acute Respiratory Syndrome Identified Serum Amyloid A Protein as a Biomarker Potentially Useful in Monitoring the Extent of Pneumonia

Acute serumamyloid A is an endogenous TLR2

ligand that mediates inflammatory and angiogenic mechanisms

Serum amyloid A-a review

Clinical features of patients infected with 2019 novel coronavirus in Wuhan

Cytokine control of megakaryopoiesis

The use of PCT, CRP, IL•6 and SAA in critically ill patients for an early distinction between candidemia and Gram positive/negative bacteremia

Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan,China

Inflammatory impact of IFN-γ in CD8+T cellmediated lung injury is mediated by both Stat1-dependent and-independent pathways

The reproductive number of COVID-19 is higher compared to SARS coronavirus

On behalf of the authors, We sincerely thank clinicians in Tianyou Hospital Affiliated to Wuhan University of Science and Technology for their dedication.

This study was approved by the Medical Ethics Review Board of Wuhan University of Science and Technology (No. 202009).

The authors declare that they have no competing interests. 16 181 Normal reference values: SAA (<10mg / L); CRP (<3mg / L); WBC (3.5-9.5 × 10 9 / L); L (1.1-3.2 × 10 9 / L); PCT (<0.05ug /L); PLT (125-350 × 10 9 / L)