Serum Krebs von den Lungen-6 is associated with in-Hospital mortality of patients with severe Community-Acquired Pneumonia: A retrospective cohort study

Abstract

BackgroundCurrently, no ideal biomarker can accurately stratify the risk of patients with severe community-acquired pneumonia (SCAP). This study aimed to evaluate the role of serum Krebs von den Lungen-6 (sKL-6) in predicting in-hospital mortality in adults with SCAP. MethodsIn this retrospective cohort study, 249 severe pneumonia adult patients were recruited between 6 May 2021 to 30 April 2023 in Xiangya Hospital of Central South University. The sKL-6 level within 48 h of admission was measured, and the primary outcome assessed was in-hospital mortality. Multivariable logistic regression analysis was performed to calculate adjusted odds ratios (OR) with 95% confidence intervals (CI). Survival curves were plotted and subgroup analyses were conducted, stratified by relevant covariates. ResultsA total of 249 patients were included in the study,with 124 patients having normal sKL-6 levels, and 125 patients having abnormal sKL-6 levels. The overall in-hospital mortality rate was 28.9% (72 out of 249 patients). Univariate and multivariate logistic regression analysis revealed that the patients with abnormal sKL-6 levels had a higher risk of in-hospital mortality compared to those with normal sKL-6 levels, both in the total SCAP patient population (OR: 5.38, 95%CI: 2.41–12.01, P < 0.001) and the non-COVID-19 SCAP patients subgroup (OR: 8.12, 95%CI: 3.16–20.84, P < 0.001). Subgroup and interaction analyses confirmed the stability of the relationship between sKL-6 levels and in-hospital mortality(P for interaction > 0.05). Kaplan-Meier survival curves showed that patients with abnormal sKL-6 levels had a higher in-hospital mortality rate than those with normal sKL-6 levels (P < 0.05). However, the results of restricted cubic spline plots(RCS) analysis demonstrated a nonlinear association between sKL-6 levels (as a continuous variable) and in-hospital mortality in patients with SCAP. Similar results were observed in non-COVID-19 SCAP patients. Furthermore, the receiver operating characteristic curve (ROC) analysis revealed that sKL-6 had superior predictive performance compared to existing biomarkers (e.g., APACHE-II, SOFA, BUN/Cr, PCT, and D-dimer) for in-hospital mortality in non-COVID-19 SCAP patients. ConclusionsKL-6 is a practical and useful biomarker for predicting in-hospital mortality in patients with SCAP.