Validating the 6-minute walk test as an indicator of recovery in patients undergoing cardiac surgery: A prospective cohort study

The 6-minute walk test (6MWT) has been applied to assess postsurgical recovery in cardiac populations. This study mainly investigated whether the 6MWT could serve as an indicator for physical functioning in patients undergoing cardiac surgery. Participants completed the 6MWT and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) at baseline, discharge, and 3 months postoperatively, in order to analyze the construct validity and responsiveness of the 6MWT. The participants in this study were 125 patients (92 males and 33 females) with an average age of 65.1 ± 11.1 years. The mean 6MWT was 308.9 ± 77.3 m in the preoperative phase, decreased to 277.3 ± 85.7 m at discharge, and returned to 378.1 ± 95.2 m at 3-month follow-up. The results showed that the 6-minute walk distances at baseline and at 3-month follow-up were moderately to highly correlated with the physical functioning subscale of the SF-36 (r(s) = .44 and .54, respectively) and had weak correlation with the nonphysical functioning subscales. The recovery level of physical functioning is meaningfully associated with the 6MWT change from baseline to discharge and from baseline to 3-month follow-up. Patients with higher New York Heart Association (NYHA) Functional Classification levels had lower 6MWT. Additionally, the 6MWT was sensitive to change during the perioperative period (effect sizes from −0.51 to 1.72). The supporting evidence includes the construct validity and responsiveness of the 6MWT. This study supports the feasibility of the 6MWT as an evaluation tool of physical functioning for assessment of postcardiac surgical recovery.