Determinants of the prognosis of idiopathic pulmonary fibrosis

Fibrotic idiopathic interstitial pneumonias are chronic and progressive lung diseases with different prognosis, with idiopathic pulmonary fibrosis (IPF) having the worst prognosis. Many patients need a surgical lung biopsy for the definite diagnosis of IPF but age and the clinical context often contraindicate this procedure. The aim of this study is to identify predictors of survival, apart from lung biopsy, in patients with definite and possible IPF.

We studied 42 patients with HRCT pattern of definite or possible IPF, by assessing the mortality in relationship with baseline HRCT and functional findings. HRCT was assessed both as prevalent pattern (definite vs possible UIP) and as score of the different abnormalities (in particular, honeycombing (HC) and total fibrotic score). Pulmonary function was assessed as baseline FVC, TLC and DLCO values, as well as change over 6 months of follow-up. Both univariate and multivariate analyses were performed in order to detect predictors of mortality.

During follow-up, 10 out of 42 patients died. Mortality rate was not different according to the qualitative pattern of fibrosis at HRCT. Among the different HRCT scores, a cut-off of 15% in the HC score differentiated patients with higher mortality rate. A lower baseline FVC, and a greater decrease in pulmonary function after 6 months, were both associated with higher mortality. In a logistic analysis taking in consideration clinical, radiological and functional findings, only baseline FVC and FVC change after 6 months resulted significant predictors of mortality.

Functional evaluation at the baseline and during follow-up is more relevant than HC score for the prognosis of patients with definite and possible IPF.