Walking distance on 6-MWT is a prognostic factor in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with high mortality rates and a median survival of 2-3 years from time of diagnosis. The prognosis for any individual patient, however, is variable. To elucidate the clinical significance of 6-min walking test (6-MWT) in patients with IPF, we sought to assess the relationship between distance walked and desaturation during this test and pulmonary function tests (PFTs). We also evaluate the prognostic value of 6-MWT in comparison with PFTs at baseline and during follow-up.

The clinical data of 44 patients with IPF were retrospectively analysed. Twenty-nine patients had an additional evaluation after 12 month of follow-up.

Distance walked in 6 min was independently related to mortality by multivariate analysis. Patients walking less then 212 m had a significantly lower survival than those walking farther, assessed by Kaplan-Meier survival curves (log-rank test, p<0.036). During a mean follow-up period of 19.8 months (range 3.2-46.4), 11 patients died of causes related to disease. Changes in meters walked at 12 months evaluation were also predictive of survival (p=0.05).

These results confirm that in IPF distance walked in 6 min is independent associated with mortality.