Serum surfactant protein-A is a strong predictor of early mortality in idiopathic pulmonary fibrosis.
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.
Kinder
Brent W
BW
Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Cincinnati College of Medicine; Cincinnati, OH. Electronic address: brent.kinder@uc.edu.
Brown
Kevin K
KK
Department of Medicine, National Jewish Medical and Research Center, Denver, CO.
McCormack
Francis X
FX
Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Cincinnati College of Medicine; Cincinnati, OH.
Ix
Joachim H
JH
Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, San Diego, CA.
Kervitsky
Alma
A
Department of Medicine, National Jewish Medical and Research Center, Denver, CO.
Schwarz
Marvin I
MI
Department of Medicine, National Jewish Medical and Research Center, Denver, CO.
King
Talmadge E
TE
Department of Medicine, University of California, San Francisco School of Medicine, San Francisco, CA.
D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001707:Biopsy, Needle; D001992:Bronchoalveolar Lavage Fluid; D002423:Cause of Death; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000097:blood* / Q000401:mortality* / Q000473:pathology; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011336:Probability; D011446:Prospective Studies; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood* / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood* / Q000378:metabolism; D012372:ROC Curve; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012737:Sex Factors; D016019:Survival Analysis; D013997:Time Factors
D015415:Biomarkers; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D