Gabriel C Brooks, Eric Vittinghoff, Sivaraman Iyer, Damini Tandon, Peter Kuhar, Kristine A Madsen, Gregory M Marcus, Mark J Pletcher, Jeffrey E Olgin

-The 6-minute walk test (6MWT) independently predicts congestive heart failure (CHF) severity, death and heart failure hospitalizations, but must be administered in clinic by qualified staff on a pre-measured course. As part of the Health eHeart Study we sought to develop and validate a self-administered 6MWT mobile application (SA-6MWTapp) for independent use at home by patients. -We performed a validation study of a SA-6MWTapp in 103-participants. In phase one (n=52), we developed a distance estimation algorithm for the SA-6MWTapp by comparing step counts from an Actigraph and measured distance on a pre-measured 6MWT course to step counts and estimated distance obtained simultaneously from our SA-6MWTapp (best estimation algorithm, r = 0.89 [95% CI 0.78 - 0.99]). In phase two, 32 participants (including those with CHF and pHTN) used the SA-6MWTapp independently in clinic and the distance estimated by the SA-6MWTapp was compared to the measured distance (r = 0.83 [95% CI 0.79-0.92]). In phase three, 19 patients with CHF and pHTN consecutively enrolled from clinic, performed 3.2 ±1 SA-6MWTapp tests per week at home over 2 weeks. Distances estimated from the SA-6MWTapp during home 6MWTs were highly repeatable (coefficient of variation = 4.6%) and correlated with in-clinic measured distance (r = 0.88 [95% CI 0.87-0.89]). Usability surveys performed during the second (in-clinic) and third (at-home) phases demonstrated that the SA-6MWTapp was simple and easy to use independently. -A self-administered 6MWTapp is easy to use and yields accurate repeatable measurements in the clinic and at home.