Six-Minute Walk Test and Health-Related Quality of Life: Objective Tools to Assess Improvement in Cystic Fibrosis Patients Hospitalized for Pulmonary Exacerbation

Abstract

The 6 Minute Walk Test (6 MWT) has been shown to be a better test for submaximal exercise capacity than other submaximal exercise tests. The cystic fibrosis (CF) Health-Related Quality of Life Cystic Fibrosis Questionnaire-Revised (CFQ-R) has been used in CF patients in order to assess the quality of life. There are a few studies that examine measurements of multiple endpoints simultaneously [e.g., pulmonary function test (PFT), exercise capacity, CFQ-R] with treatment in CF pulmonary exacerbation. We hypothesize that the 6MWT is safe to perform during pulmonary exacerbation, and that 6 MWT, CFQ-R, and PFT improve with treatment in CF pulmonary exacerbation. We further hypothesized that the improvements in 6MWT, CFQ-R, and PFT are related. We performed 6 MWT, PFT, and CFQ-R in 21 CF subjects (age 7–20 years) admitted for pulmonary exacerbation. 6 MWT, PFT, and CFQ-R were completed at admission, at the end of week 1, and at the end of week 2. No complications were noted during the 6MWT.The 6MWT, PFT [forced expiratory volume in one second (FEV1), FVC and forced expiratory flow25%–75% (FEF25%–75%)], and CFQ-R domains (Respiratory and Physical) improved significantly at week 2. The physical domain change correlated with the 6MWT improvement, whereas the respiratory domain change correlated with the FEF 25%–75% improvement at week 2. There was no significant relationship observed between the 6MWT and PFT improvements. In conclusion, 6MWT is a safe and well-tolerated test, and it can be utilized as an adjunct or alternative outcome measure to PFT in acute CF pulmonary exacerbation. In addition, multiple outcome measures, including 6MWT and HRQOL, should be utilized to assess the efficacy of treatment in CF pulmonary exacerbation.