Association of procalcitonin levels with the progression and prognosis of hospitalized patients with COVID-19.

Rationale: Coronavirus disease 2019 (COVID-19) was first announced in Wuhan, and has rapidly evolved into a pandemic. However, the risk factors associated with the severity and mortality of COVID-19 are yet to be described in detail. Methods: We retrospectively reviewed the information of 1525 cases from the Leishenshan Hospital in Wuhan. Univariate and multivariate Cox regression analyses were generated to explore the relationship between procalcitonin (PCT) level and the progression and prognosis of COVID-19. Univariate and multivariate logistic regression analyses were performed to explore the relationship between disease severity in hospitalized patients and their PCT levels. Survival curves and the cumulative hazard function for COVID-19 progression were conducted in the two groups. To further detect the relationship between the computed tomography score and survival days, curve-fitting analyses were performed. Results: Patients in the elevated PCT group had a higher incidence of severe and critical severity conditions (P < 0.001), death, and higher computed tomography (CT) scores. There was an association between elevated PCT levels and mortality in the univariate ((hazard ratio [1], 3.377; 95% confidence interval [2], 1.012-10.344; P = 0.033) and multivariate Cox regression analysis (HR, 4.933; 95% CI, 1.170-20.788; P = 0.030). Similarly, patients with elevated PCT were more likely to have critically severe disease conditions in the univariate (odds ratio [2], 7.247; 95% CI, 3.559-14.757; P < 0.001) and multivariate logistic regression analysis (OR, 10.679; 95% CI, 4.562-25.000; P < 0.001). Kaplan-Meier curves showed poorer prognosis for patients with elevated PCT (P = 0.024). The CT score 1 for patients with elevated PCT peaked at day 40 following the onset of symptoms then decreased gradually, while their total CT score was relatively stable. Conclusion: PCT level was shown as an independent risk factor of in-hospital mortality among COVID-19 patients. Compared with inpatients with normal PCT levels, inpatients with elevated PCT levels had a higher risk for overall mortality and critically severe disease. These findings may provide guidance for improving the prognosis of patients with critically severe COVID-19.

Measurement of serum IgG4 levels by an established ELISA system and its clinical applications in autoimmune diseases.

IgG4-related disease (IgG4-RD) is a novel and rare autoimmune disease entity. Elevated serum IgG4 level is strongly suggestive of IgG4-RD. But it is still unknown whether serum IgG4 elevation commonly occurs in other autoimmune diseases. In this study, the serum IgG4 levels were detected by an established enzyme-linked immunosorbent assay (ELISA) in a variety of autoimmune diseases including systemic lupus erythematosus (SLE), Sjogren's syndrome (SS), polymyositis or dermatomyositis (PM/DM) and IgG4-RD. To evaluate the reliability of this ELISA system, some of our samples were sent to a lab in Kanazawa Medical University, Japan, and detected by using the nephelometric assay. The results showed that our findings were consistent with theirs. Moreover, it was found that the serum IgG4 levels were 0.23±0.16 g/L in 53 healthy controls, 0.16±0.15 g/L in 103 SLE patients, 0.22±0.18 g/L in 41 SS patients and 0.40±0.32 g/L in 21 PM/DM patients. No significant difference in the serum IgG4 level was observed among these groups (P>0.05). The serum IgG4 levels of two cases of IgG4-RD were 1.63 and 4.65 g/L respectively, and both decreased markedly after treatment with glucocorticoids. These data indicated that this established ELISA system can be used for detecting serum IgG4 levels. Elevated serum IgG4 levels help diagnose IgG4-RD and evaluate the curative effect of this condition rather than other autoimmune diseases.