Idiopathic Pulmonary Fibrosis (IPF) is a bad prognosis disease with heterogeneous progression. Only few studies, including relative small sample size, have searched for bad prognosis factors. The aim of this study was to analyze survival predictors in a retrospective cohort.
The study was conducted at the National Thorax Institute in Santiago, Chile. Registers of patients in the period between 1991 and 2008 with clinical, radiological and surgical biopsy concordant with IPF were analyzed. We performed survival analysis with mixed models and proportional Weibull hazard models.
A total of 142 patients were analyzed. The average age was 58 years and 41.5% were males.

Table 1. Results of pulmonary function tests at baseline
 Mean (SD)
Forced vital capacity (ml)2400 (770)
Forced vital capacity (%)73 (20)
DLCO (ml/min/mm Hg)14.0 (4.8)
DLCO (%)57.8 (16.3)
6MWT (m)477 (83)
6WMT (%)95.3 (17.4)
SD: Standard deviation. DLCO: Diffusing capacity of the lungs for carbon monoxide. 6MWT: Six minute walk test.

The mean survival was 80 months. In univariate analysis were predictors of mortality: diffusing capacity of the lung for carbon monoxide (DLCO) less of forty percent and desaturation during six minute walk test (6MWT) at baseline. The rate of decline of forced vital capacity (FVC) was mortality predictor.

The rate of decline of FVC is a strong mortality predictor in this study and allows distinguishing bad prognosis groups.