Serum surfactant protein-A is a strong predictor of early mortality in idiopathic pulmonary fibrosis

Chest. 2009 Jun;135(6):1557-1563. doi: 10.1378/chest.08-2209. Epub 2009 Mar 2.


Background: Serum surfactant protein (SP) A and SP-D had prognostic value for mortality in patients with idiopathic pulmonary fibrosis (IPF) in prior studies before the reclassification of the idiopathic interstitial pneumonias. We hypothesized that baseline serum SP-A and SP-D concentrations would be independently associated with mortality among patients with biopsy-proven IPF and would improve a prediction model for mortality.

Methods: We evaluated the association between serum SP-A and SP-D concentrations and mortality in 82 patients with surgical lung biopsy-proven IPF. Regression models with clinical predictors alone and clinical and biomarker predictors were used to predict mortality at 1 year.

Results: After controlling for known clinical predictors of mortality, we found that each increase of 49 ng/mL (1 SD) in baseline SP-A level was associated with a 3.3-fold increased risk of mortality (adjusted hazard ratio, 3.27; 95% confidence interval, 1.49 to 7.17; adjusted p = 0.003) in the first year after presentation. We did not observe a statistically significant association between serum SP-D and mortality (adjusted hazard ratio, 2.04; p = 0.053). Regression models demonstrated a significant improvement in the 1-year mortality prediction model when serum SP-A and SP-D (area under the receiving operator curve [AROC], 0.89) were added to the clinical predictors alone (AROC, 0.79; p = 0.03).

Conclusions: Increased serum SP-A level is a strong and independent predictor of early mortality among patients with IPF. A prediction model containing SP-A and SP-D was substantially superior to a model with clinical predictors alone.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aged
  • Biomarkers / blood
  • Biopsy, Needle
  • Bronchoalveolar Lavage Fluid
  • Cause of Death*
  • Cohort Studies
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Idiopathic Pulmonary Fibrosis / blood*
  • Idiopathic Pulmonary Fibrosis / mortality*
  • Idiopathic Pulmonary Fibrosis / pathology
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Probability
  • Prospective Studies
  • Pulmonary Surfactant-Associated Protein A / blood*
  • Pulmonary Surfactant-Associated Protein A / metabolism
  • Pulmonary Surfactant-Associated Protein D / blood*
  • Pulmonary Surfactant-Associated Protein D / metabolism
  • ROC Curve
  • Risk Assessment
  • Sensitivity and Specificity
  • Severity of Illness Index
  • Sex Factors
  • Survival Analysis
  • Time Factors


  • Biomarkers
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Protein D