Clinical predictors of survival in idiopathic pulmonary fibrosis

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive disease. Effective treatment is not currently available and the prognosis is poor. The aim of our study was to identify clinical predictors of survival in patients with IPF.

Methods: By using medical record database of a university hospital, we reviewed the records of patients who had been diagnosed as having IPF from January 1996 through December 2007.

Results: Among 89 patients considered as having interstitial lung disease (ILD) on computed tomography (CT) of the chest, 22 were excluded because of the diagnosis of other ILDs or connective tissue disease, and finally, 67 met the criteria of IPF. The mean age at the diagnosis of IPF was 70 years (range, 41~87 years) and 43 (64%) were male. The mean survival time following the diagnosis of IPF was 40 months (range, 0~179 months). Among them, 28 cases were diagnosed as the progressive state of IPF on the follow-up CT examination, and the mean duration between diagnosis of IPF and progression was 31 months. Multivariate analysis using Cox regression model revealed that body mass index (BMI) less than 18.5 kg/m(2) (p=0.030; hazard ratio [HR], 12.085; 95% confidence interval [CI], 1.277~114.331) and CT progression before 36 months from the diagnosis of IPF (p=0.042; HR, 13.564; 95% CI, 1.101~167.166) were independently associated with mortality.

Conclusion: Since low BMI at the diagnosis of IPF and progression on follow-up CT were associated with poor prognosis, IPF patients with low BMI and/or progression before 36 months following the diagnosis should be closely monitored.

Keywords: Body Mass Index; Disease Progression; Idiopathic Pulmonary Fibrosis.

Figure 1

Comparison of overall survival by Kaplan-Meier method. (A) Disease progression on computed tomography (CT) before 36 months following the diagnosis. (B) Initial body mass index. p-value by Log rank test.