Objective: The 6 Minute Walk Test (6MWT) is a measure that is routinely used to assess a response to treatment for cardiopulmonary diseases such as pulmonary fibrosis and congestive heart failure. The measure has never been verified as a valid measure of exercise capacity in the highly prevalent patient population of type 2 diabetes (T2DM). This study investigated the correlation between the 6MWT and graded exercise testing (GXT) in an effort to validate the 6MWT as a quality tool for assessing exercise capacity in adults with T2DM.
Research design and method: This is a secondary data analysis of Program ACTIVE II, a randomized controlled trial designed to assess the effectiveness of two behavioral interventions on depression and glycemic outcomes in adults with T2DM. The correlation of 6MWT and predicted VO2 max (PVO2M) using GXT was examined in a subsample of participants at the time of study enrollment and at post-intervention.
Results: PVO2M showed a significant correlation with 6MWT distance both at baseline (r=0.57, p=0.014) and post-intervention (r = 0.66, p = 0.037). The regression analysis of baseline data revealed that 6MWT distance alone explained 45% (F = 13.03, p = .0024) of the variability in PVO2M. When combined with the SF-12 physical health component score (PCS), 6MWT explained 66% (F = 13.62, p < .001) of the variance in PVO2M. After adjusting for PCS, 6MWT distance explained an additional 30% variability in PVO2M.
Conclusions: Findings from this study indicate that the 6MWT and predicted exercise capacity are significantly correlated. The 6MWT can be used to estimate exercise capacity in adults with T2DM.