Prognostic value of circulating KL-6 in idiopathic pulmonary fibrosis

Respirology. 2006 Mar;11(2):164-8. doi: 10.1111/j.1440-1843.2006.00834.x.


Objective: Circulating levels of KL-6, a high MW glycoprotein (MUC1 mucin), are elevated in a majority of patients with a number of interstitial lung diseases, including idiopathic pulmonary fibrosis (IPF). However, KL-6 levels vary from patient to patient. The aim of the present study was to determine whether the serum KL-6 level at the time of diagnosis predicts prognosis in IPF.

Methods: The relationship between clinical variables and prognosis in 27 patients with IPF were analysed retrospectively. The diagnosis was made by histological examination (n = 16) or on clinical findings including high-resolution CT scanning (n = 11). All patients were followed up for at least 3 years. Variables such as age, FVC%, PaO(2) at rest, initial LDH level, C-reactive protein and KL-6 were used for analysis.

Results: At the cut-off level determined by receiver operating characteristic curves, LDH and KL-6 showed a significant correlation with the patient's prognosis by univariate analysis. However, multivariate analysis revealed that only KL-6 was a predictor of prognosis. The patients were categorized by their serum KL-6 levels (as above or below the cut-off level of 1000 U/mL) and their survival estimated using the Kaplan-Meier method. The difference in median survival between the two groups was significant. The median survival of patients with low KL-6 was more than 36 months, whereas that of patients with high KL-6 was only 18 months.

Conclusion: These results suggest that initial evaluation of serum KL-6 level can predict survival in patients with IPF.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Neoplasm / blood*
  • Biomarkers / blood
  • C-Reactive Protein / metabolism
  • Female
  • Follow-Up Studies
  • Forced Expiratory Volume
  • Humans
  • Male
  • Middle Aged
  • Mucin-1
  • Mucins / blood*
  • Prognosis
  • Pulmonary Fibrosis / blood*
  • Pulmonary Fibrosis / diagnosis
  • Pulmonary Fibrosis / physiopathology
  • ROC Curve
  • Retrospective Studies
  • Severity of Illness Index
  • Tomography, X-Ray Computed


  • Antigens, Neoplasm
  • Biomarkers
  • MUC1 protein, human
  • Mucin-1
  • Mucins
  • C-Reactive Protein