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

•SCAP patients with abnormal sKL-6 levels had increased in-hospital mortality compared to patients with normal sKL-6 levels (OR = 5.38, 95%CI: 2.41–12.01).•Compared to existing biomarkers, such as APACHE-II, SOFA, BUN/Cr, PCT, and D-dimer, sKL-6 was better at predicting in-hospital mortality in non-COVID-19 SCAP patients.•The positive relationship between sKL-6 levels and in-hospital mortality was non-linear and had a threshold effect.•This study showed sKL-6 might be a practical and good biomarker for predicting in-hospital mortality in patients with SCAP, which may help clinicians provide timely and personalized treatment to these patients.