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

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.