Detection of serum KL-6 and SARS-CoV-2 antibody in patients with coronavirus disease 2019 and the diagnostic value in severe disease

Abstract

Background Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a significant threat to human health, but its clinical manifestations vary greatly among individuals. Early detection and treatment are important for severely ill patients to improve their prognosis and reduce the risk of death. Methods In the present study, serum markers were detected and analyzed in moderately ill and severely ill patients. Results The results found that there were statistically significant differences in age, serum Krebs von den Lungen-6 (KL-6) and Immunoglobulin A (IgA) levels between severely ill patients and moderately ill patients (P < 0.05). The cut-off of using KL-6 alone for the diagnosis of severely ill patients was 298.91 U/mL, with an AUC of 0.737, a sensitivity of 100%, and a specificity of 43%. When the diagnosis was performed using KL-6 in combination with Interleukin-6 (IL-6), an indicator of infection, the AUC was 0.776, with a sensitivity and specificity of 82% and 69%, respectively. When the three above were used in combination for diagnosis, the AUC was 0.785, and the sensitivity and specificity were 100% and 59%, respectively. After rehabilitation, the serum levels of KL-6, C-reactive protein (CRP), as well as antibodies, IgA, IgM and IgG, were significantly lower than those in the early stage of hospitalization. Conclusion In the present study, KL-6 and IgA were found to have some diagnostic efficacy for severely ill patients with COVID-19, but larger cohort studies are still needed for further confirmation, which in turn improves the diagnostic and therapeutic efficiency of severely ill patients.

Prediction Value of KREBS Von Den Lungen-6 (KL-6) Biomarker in COVID-19 Patients: A Systematic Review and Meta-Analysis

“…These articles were re-evaluated based on full-text contents, resulting in exclusion of 8 articles. Finally, 15 studies met the inclusion criteria and were included in our meta-analysis ( Figure 1 ) [ 5 , 8 , 12 , 14 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. All selected studies were published between 2020 and 2022.…”

“…Greater clinical value could be found in using KL-6 at admission to predict the subsequent course of COVID-19. Twelve studies involved in our meta-analysis assessed the KL-6 level according to the disease severity [ 6 , 8 , 14 , 19 , 20 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Our analysis demonstrated that there was a significantly higher level of KL-6 in patients suffering from severe COVID-19 than mild-to-moderate.…”

“…The center of each square represents the mean differences for individual trials, and the corresponding horizontal line stands for a 95% confidence interval. The diamonds represent pooled results [ 5 , 8 , 14 , 19 , 20 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

Serum Krebs von den Lungen-6 for Predicting the Severity of COVID-19: A Systematic Review, Meta-Analysis, and Trial Sequence Analysis

“…For sensitivity and specificity, data were extracted from eight studies with their baseline values. 9 , 12 , 15 , 17 – 19 , 21 , 32 The data for sensitivity, and specificity analysis is presented in Supplementary file ( Appendix 4 ). For diagnostic studies, the Summary Receiver Operating Curve (sROC) was performed to summarize TP and FP rates.…”

“…Among these Krebs von den Lungen-6 (KL-6) factor has also been established as a possible severity marker and prognostic tool by various articles. 9 – 21 …”