Krebs von den lungen-6 as a predictive indicator for the risk of secondary pulmonary fibrosis and its reversibility in covid-19 patients

Mingshan Xue, Teng Zhang, Hao Chen, Yifeng Zeng, Runpei Lin, Yingjie Zhen, Ning Li, Zhifeng Huang, Haisheng Hu, Luqian Zhou, Hui Wang, Xiaohua Douglas Zhang, Baoqing Sun

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Dysregulated immune response and abnormal repairment could cause secondary pulmonary fibrosis of varying severity in COVID-19, especially for the elders. The Krebs Von den Lungen-6 (KL-6) as a sensitive marker reflects the degree of fibrosis and this study will focus on analyzing the evaluative efficacy and predictive role of KL-6 in COVID-19 secondary pulmonary fibrosis. The study lasted more than three months and included total 289 COVID-19 patients who were divided into moderate (n=226) and severe groups (n=63) according to the severity of illness. Clinical information such as inflammation indicators, radiological results and lung function tests were collected. The time points of nucleic acid test were also recorded. Furthermore, based on Chest radiology detection, it was identified that 80 (27.7%) patients developed reversible pulmonary fibrosis and 34 (11.8%) patients developed irreversible pulmonary fibrosis. Receiver operating characteristic (ROC) curve analysis shows that KL-6 could diagnose the severity of COVID-19 (AUC=0.862) and predict the occurrence of pulmonary fibrosis (AUC = 0.741) and irreversible pulmonary fibrosis (AUC=0.872). Importantly, the cross-correlation analysis demonstrates that KL-6 rises earlier than the development of lung radiology fibrosis, thus also illuminating the predictive function of KL-6. We set specific values (505U/mL and 674U/mL) for KL-6 in order to assess the risk of pulmonary fibrosis after SARS-CoV-2 infection. The survival curves for days in hospital show that the higher the KL-6 levels, the longer the hospital stay (P<0.0001). In conclusion, KL-6 could be used as an important predictor to evaluate the secondary pulmonary fibrosis degree for COVID-19.

Original languageEnglish
Pages (from-to)1565-1573
Number of pages9
JournalInternational Journal of Biological Sciences
Issue number6
StatePublished - 2021

Bibliographical note

Publisher Copyright:
© The author(s).


  • Coronavirus disease 2019
  • Krebs von den Lungen-6
  • Pulmonary fibrosis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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