Predictive Utility of the 6-Minute Walk Distance on Survival in Patients Awaiting Lung Transplantation

Background

The 6-minute walk distance (6MWD) is a widely used clinical indicator of exercise capacity. Although used as part of the assessment process in determining a candidate's suitability for lung transplantation (LT), the literature describing the impact of the 6MWD in predicting survival on LT waiting lists is limited. This study aimed to determine the hazard function associated with the 6MWD, and its utility relative to other prognostic variables.

Methods

A retrospective chart review was conducted on 163 patients who were listed for single or double LT, and either survived to transplant or died while on the waiting list. A Cox regression for survival analysis, stratified by diagnostic group, was conducted utilizing the 6MWD, demographic variables and measures of cardiopulmonary function.

Results

The 6MWD proved to be the only significant covariate in the Cox regression for survival analysis (p < 0.001), with all other variables eliminated as non-significant. Furthermore, there was a protective effect for each unit increase in the 6MWD [Exp (B) = 0.994, 95% confidence interval 0.990 to 0.997].

Conclusions

This research demonstrates that the 6MWD is useful for stratifying patients on the LT waiting list by identifying those patients with a significantly higher risk of mortality.