Idiopathic pulmonary fibrosis(IPF) is a fatal progressive fibrous disease of the lung of unknown etiology. Recently it has been classified into several distinct entities of the basis of pathologic and clinical characteristics, ie : usual interstitial pneumonia(UIP), desquamative interstitial pneumonia(DIP), acute interstitial pneumonia(AIP), bronchiolitis obliterans with organizing pneumonia(BOOP), and nonspecific interstitial pneumonia(NSIP). IPF is now applied only for UIP, which has the worst prognosis. The previous reports of 3-5 year median survival apears to be overoptimistic because other types with better prognosis like NSIP or BOOP might have been included. Therefore, this study was performed to determine the clinical course and the prognostic factors of UIP as diagnosed by surgical lung biopsy.

The subjects were 72 UIP patients (age 58.2±11.6 years, M:F=45:27, median follow up period:18.1 months (0.7-103.6) diagnosed by surgical lung biopsy at the Asan Medical Center (68 patients) and the Paik Hospital in Seoul (4 patients). Clinical scores (level of dyspnea:1-20 points), radiologic score (honey-combing : HC score 0-5 points, ground glass : GG score 0-5 points), and physiologic scores (FVC:1-12 points, FEV1:0-3 points, TLC:0-10 points, DDLC:0-5 points, AaDO2:0-10 points) were summed into a total CRP score.

1) The one year survival rate was 78.3%, while the rate for three year survival was 58.1%, and the median survival period was 42.5 months. 2) Short term (1 year) prognosis : The patients who died within one year of diagnosis (14 patients) had the higher initial total CRP score (28.6±8.3 vs. 16.6±9.7) than those who lived longer than one year (46 patients). The difference in the total CRP score was attributed to the symptom score (8.4±2.1 vs. 5.7±3.9) and the physiologic score (15.7±7.1 vs. 6.7±5.7) including FVC, DLCO, and AaDO2. 3) Long-term (3 year) prognosis : The total CRP score (12.2±6.7 vs. 28.7±7.9:including symptom score, FVC, DLCO, and AaDO2) at the time of diagnosis were also different for the long-term survivors and those who lived less than 3 years. 4) Cox regression analysis showed LCO (≥60%) (Hazard ratio:4.56, 95% CI:2.30-16.04) was the independent prognostic factors of UIP (P<0.05).

These results suggest that DLCO at the time of diagnosis seem to be a prognostic markers of biopsy-proven UIP.