The 6 Minute Walk Test as a predictor of mortality in idiopathic pulmonary fibrosis: A systematic review

Abstract

Background

The 6-min walk test (6MWT) is frequently used in pulmonary fibrosis (PF) research. It evaluates an individual's sub-maximal exercise performance by measuring the distance they walk and their vital signs across 6 min. In research studies, the 6-min walk distance (6MWD) is often used as a surrogate marker for disease progression. The aim of this study was to systematically assess the association between 6MWT parameters and mortality in PF.

Methods

MEDLINE, EMBASE, CINAHL, and CENTRAL databases were searched for studies reporting mortality and 6MWD in patients with PF. Study quality was assessed using a modified Newcastle-Ottawa Scale. Studies were included if they reported associations between the 6MWT in pulmonary fibrosis and mortality. Results were presented as a narrative synthesis.

Results

2312 studies were identified, 22 studies met the pre-defined inclusion criteria, comprising 5940 Idiopathic PF patients. Baseline 6MWD was found to be loosely associated with mortality (Ranges: univariate HR 0.89–4.72, multivariate HR 0.96–2.65), while a decrease in 6MWD across 24-weeks was correlated with a higher risk of mortality (Ranges: univariate HR 2.25–4.81, multivariate HR 1.72–4.3).

Discussion

This review found that a low baseline 6MWD, and a 6-month decrease in 6MWD were strongly correlated with increased mortality in Idiopathic PF patients. As the 6MWT is a safe, easy-to-conduct test, it is appropriate for use as a marker of patient prognosis, in both clinical and research settings.

Open science framework protocol registration

DOI 10.17605/OSF.IO/3D7BV.