The clinical value of laboratory inflammation indicators in the diagnosis and treatment of COVID-19 patients

To explore the clinical value of lymphocyte count, C-reactive protein, serum amyloid A, procalcitonin and other inflammatory indicators in the diagnosis and treatment of patients with new coronavirus pneumonia (COVID-19).

The clinical data of 77 patients with new coronavirus pneumonia diagnosed in Beijing Ditan Hospital from February to March 2020 were collected. According to the diagnosis and treatment plan, they were divided into 49 cases of general type and 28 cases of severe type, of which 19 cases were discharged. Compare the differences in lymphocyte count, CRP, SAA, PCT and other indicators of ordinary, severe and discharged patients, and screen out indicators with better predictive value for disease progression and prognosis through Logistic regression and ROC curve analysis.

Compared with the normal type, the lymphocyte count of severe patients was significantly reduced (P=0.000), CRP and SAA were significantly increased (P=0.000, P=0.000), and the positive rate of PCT was significantly increased (χ2=11.003, P=0.001) ; The lymphocyte count of discharged patients was significantly higher than that of ordinary (P=0.001) and severe patients (P=0.000), while CRP (P=0.036, P=0.000) and SAA (P=0.002, P=0.000) ) Were significantly reduced; the positive rate of PCT in discharged patients was significantly lower than that of severe patients (χ2=6.891, P=0.009), but there was no significant difference compared with the normal type (χ2=0.169, P=0.681). Multivariate logistic regression analysis showed that both SAA and CRP increase are risk factors for predicting the occurrence of severe disease, while SAA reduction can be used as an independent indicator for predicting discharge; ROC curve analysis SAA has a sensitivity of 85.71% and a specificity of 87.76%. The sensitivity of CRP was 82.14% and the specificity was 93.88%; the sensitivity of SAA to diagnose discharge was 100%, and the specificity was 57.89%.

Inflammatory indicators such as lymphocyte count, CRP, SAA, and PCT have important clinical significance for the diagnosis and treatment of patients with new coronavirus pneumonia. Among them, SAA is an independent indicator that is more sensitive to evaluate disease progression and prognosis.

The purpose of this research is to focus on the lymphocyte count, C-reactive protein (CRP), serum amyloid A protein (SAA) and procalcitonin (PCT) commonly used in the laboratory. The indicators are analyzed retrospectively to evaluate the clinical value of each indicator in the diagnosis and treatment of COVID-19 patients, so as to provide more clinical diagnosis basis.

01 Materials and Methods

1.1 Research object

77 COVID-19 confirmed patients with complete cases who were clinically admitted in our hospital from February to March 2020 were selected as the research objects.

1.2 Detection method

Whole blood cell analysis uses Sysmex XE-5100 hematology analyzer; CRP uses particle-enhanced immunoturbidimetry, reagents are purchased from Diasys, Germany, with a reference range of 0.0~5.0mg/L; SAA uses latex immunoturbidimetry, reagents are purchased from Antu Biological Company, the reference range is 0.0~10.0mg/L; CRP and SAA are detected with Hitachi 7600 automatic biochemical analyzer; PCT adopts enzyme-linked immunofluorescence method, using French BioMérieux automatic immunoassay system (VIDAS) and For the detection of its supporting reagents, the reference range is <0.05ng/ml. All operations are carried out in accordance with the instructions. 1.3 Research object Use SPSS 22.0 software for statistical analysis. The results of non-normally distributed measurement data are expressed as the median (25th percentile, 75th percentile), and the Mann-Whitney U test is used for comparison between groups; the count data is expressed as the number of cases or percentage, and the sample rate is Χ2 test was used for comparison; Spearman rank correlation coefficient analysis was used for correlation; Logistic regression and ROC curve analysis were used for evaluation of each index. P<0.05 considered the difference to be statistically significant. 02 Result 2.1 General clinical data of 77 patients with COVID-19 pneumonia
Table 1 Clinical data of patients with new coronavirus pneumonia

2.2 Comparison of inflammatory index results in patients with COVID-19 pneumonia

The median peripheral blood lymphocyte counts of the three groups of general, severe and discharged patients were 1.70 (1.31, 1.90) × 109/L, 1.17 (0.92, 1.36) × 109/L, 2.04 (1.74, 2.40) × 109, respectively /L; CRP medians were 2.70 (0.80, 8.70) mg/L, 43.35 (23.90, 97.50) mg/L, 1.00 (0.40, 2.90) mg/L; SAA medians were 9.20 (3.10, 52.75) ) Mg/L, 355.90 (151.45, 367.88) mg/L, 3.30 (1.70, 6.00) mg/L; the positive rates of PCT were 8.16%, 50.00%, 5.26%, respectively. The lymphocyte count of severe patients was significantly lower than that of the other two groups, while the positive rates of CRP, SAA and PCT were significantly higher; the lymphocyte count of discharged patients was significantly higher than that of normal and severe patients, while CRP and SAA were significantly lower; discharged patients The positive rate of PCT is significantly lower than that of severe patients, but there is no statistical difference with the positive rate of PCT of ordinary patients, see Figure 1.

Figure 1 Comparison of multiple inflammation indicators in patients with COVID-19 pneumonia

2.3 Analysis of risk factors for severe occurrence of COVID-19 patients

The logistic regression model screened out that the increase in CRP and SAA was a risk factor for severe occurrence. The OR value of CRP was 1.166 (95% CI, 1.073-1.267), P=0.000; the OR value of SAA was 1.016 (95% CI, 1.008) -1.024), P=0.000. ROC curve analysis CRP area under the curve (AUC) is 0.924 (95% CI, 0.840-0.972), sensitivity is 82.14%, specificity is 93.88%; SAA AUC is 0.915 (95% CI, 0.829-0.966), The sensitivity is 85.71% and the specificity is 87.76%, as shown in Figure 2.

Figure 2 The sensitivity and specificity of CRP and SAA in diagnosing severe patients

2.4 Analysis of prognostic value of various inflammation indexes in COVID-19 patients

Logistic regression analysis showed that SAA is an independent prognostic indicator in evaluating the prognostic value of patients discharged from the hospital, with an OR value of 0.825 (95% CI, 0.693-0.983), P=0.031; while CRP, PCT and lymphocyte count The prognostic value is not significant, the OR value of CRP is 0.778 (95% CI, 0.596-1.014), P=0.064; the OR value of PCT is 0.210 (95% CI, 0.015-2.859), P=0.241; lymphocyte count The OR value was 1.362 (95% CI, 0.360-5.156), and P=0.649. ROC curve analysis SAA has an AUC of 0.837 (95% CI, 0.681-0.936), a sensitivity of 100%, and a specificity of 57.89%, as shown in Figure 3.

Figure 3 The sensitivity and specificity of SAA in diagnosing discharged patients

2.5 Dynamic changes of inflammatory indexes in COVID-19 patients

We retrospectively analyzed the dynamic changes of SAA, CRP, and lymphocyte counts of two patients at different time points from admission to discharge. Since PCT was not tested at some time points, PCT was not included in the continuous observation indicators, as shown in Figure 4. The basic conditions of the two patients are as follows:

Figure 4 The dynamic changes of SAA, CRP (left vertical axis) and lymphocyte count (right vertical axis) in normal and severe patients

03 Discuss

Both CRP and SAA are acute phase response proteins. The latest “New Coronavirus Diagnosis and Treatment Plan (Trial Seventh Edition)” only describes the increase in CRP levels in most COVID-19 patients, but does not mention the significance of SAA. SAA, as an acute-phase protein that is highly induced when inflammation occurs, is rapidly synthesized and released into the blood by activated macrophages and fibroblasts, and plays an important role in host defense [10]. In the early stages of infection, elevated SAA is more common than CRP, and its sensitivity is better than CRP. Clinically, combined detection of CRP and SAA is often used for the diagnosis and differentiation of infectious diseases [11]. This study found that the CRP and SAA of severe patients were significantly higher than those of ordinary and discharged patients. SAA and CRP are risk factors for severe occurrence. The rank correlation coefficient between the two is 0.886. However, SAA is a more important tool for evaluating disease progression and prognosis. Sensitive indicators. The dynamic monitoring results of the two patients showed that the changes of SAA at various time points were more consistent with the changes of the patient’s condition, and the amplitude of the rise and fall was more obvious, which was more convenient for clinical observation.

PCT is a diagnostic marker for systemic bacterial infection and sepsis, which can better evaluate the severity of infection and the efficacy of anti-infection in patients. Although most patients with mild and common types have normal PCT when they are admitted to the hospital, severe ICU patients are prone to secondary infections [12]. This study found that the positive rate of PCT in severe patients was much higher than that of ordinary and discharged patients, but there was no difference in the positive rate of PCT between ordinary and discharged patients. This may be related to the prone to secondary infections in severe patients and most of the discharged patients were ordinary. The proportion of severe patients with bacterial pneumonia was 39.3%, and the positive rate of PCT in severe patients with bacterial pneumonia was significantly increased. This suggests that we should pay attention to the possibility of severe COVID-19 patients with bacterial infection in the process of clinical treatment, and take timely intervention measures to avoid deterioration of the disease.

In summary, this article analyzes the clinical characteristics of 77 COVID-19 patients in detail, compares the differences in lymphocyte count, CRP, SAA and PCT among normal, severe, and discharged patients, and evaluates the clinical features of each inflammation index Applied value, it is found that SAA can be used as an independent test indicator to monitor changes in the condition of COVID-19 patients and evaluate prognosis.