Use of 6MWD predicts survival in fibrosing non-IPF ILD

Patients with nonidiopathic pulmonary fibrosis (non-IPF) interstitial lung disease (ILD) who show longitudinal declines in 6-min walk distance (6MWD) appear to have increased mortality, suggest the results of a recent study.

A group of researchers performed this analysis and assessed 6MWD, forced vital capacity (FVC), and diffusing lung capacity (DLCO) at baseline and at 1 year in a discovery cohort (n=105) and in a validation cohort (n=138) from various centres. Lung transplant-free survival was the primary endpoint.

Both cohorts had a mean follow-up of 3 years. The rates of death and lung transplant for both groups were 29 percent and 21 percent, respectively.

The significant associations were noted among FVC, DLCO, and 6MWD longitudinal changes. On the other hand, 6MWD decline ≥24 m correlated significantly with lung transplant-free survival and independently from FVC and DLCO declines in both the discovery and the validation cohorts. The 6MWD decline had high sensitivity and specificity.

FVC and DLCO declines also significantly predicted lung transplant-free survival, but 6MWD decline showed greater accuracy than the proposed ATS/ERS/JRS/ALAT functional criteria. These results persisted after stratifying patients by baseline FVC.

Longitudinal declines of 6MWD are largely independent from lung function decline and “may be integrated into the routine assessment of [disease] progression,” the researchers said.

“Lung function decline alone may have significant limitations in the detection of clinically significant progression,” they noted.