The Value and Application of the 6-Minute-Walk Test in Idiopathic Pulmonary Fibrosis
The 6-minute-walk test is a commonly used assessment of performance ability in a variety of cardiopulmonary diseases. It provides important functional information that is not captured in standardized pulmonary function testing. The test may be influenced by factors other than the severity of lung disease, including frailty, deconditioning, and musculoskeletal issues. The primary output measure from the 6-minute-walk test is the distance walked, which appears to confer prognostic information in many diverse disease states. The 6-minute-walk test distance has served as a primary endpoint in many drug trials, most notably in the field of pulmonary arterial hypertension, and to a lesser extent in idiopathic pulmonary fibrosis (IPF). Although the 6-minute-walk test has been used in clinical practice and research trials of IPF, there are no specific guidelines regarding its implementation in this growing patient population. Given that there is increasing evidence and experience with its use in clinical trials, development of nuanced standards designed specifically for IPF are much needed. This review touches on a number of complex and crucial issues in the application of this test and provides a framework for future development of 6-minute-walk test guidelines customized for IPF.