Accuracy and Usability of a Self-Administered 6-Minute Walk Test Smartphone Application.
BACKGROUND
The 6-minute walk test (6MWT) independently predicts congestive heart failure severity, death, and heart failure hospitalizations, but must be administered in clinic by qualified staff on a premeasured 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.


RESULTS
We performed a validation study of an SA-6MWTapp in 103 participants. In phase 1 (n=52), we developed a distance-estimation algorithm for the SA-6MWTapp by comparing step counts from an Actigraph and measured distance on a premeasured 6MWT course with step counts and estimated distance obtained simultaneously from our SA-6MWTapp (best estimation algorithm, r=0.89 [95% confidence interval 0.78-0.99]). In phase 2, 32 participants (including those with congestive heart failure and pulmonary hypertension) used the SA-6MWTapp independently in clinic, and the distance estimated by the SA-6MWTapp was compared with the measured distance (r=0.83 [95% confidence interval 0.79-0.92]). In phase 3, 19 patients with congestive heart failure and pulmonary hypertension 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% confidence interval 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.


CONCLUSIONS
An SA-6MWTapp is easy to use and yields accurate repeatable measurements in the clinic and at home.
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Gabriel C
GC
Brooks
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Eric
E
Vittinghoff
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Sivaraman
S
Iyer
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Damini
D
Tandon
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Peter
P
Kuhar
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Kristine A
KA
Madsen
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Gregory M
GM
Marcus
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.).
Mark J
MJ
Pletcher
From the Department of Medicine, Division of Cardiology (G.C.B., S.I., D.T., G.M.M., J.E.O.), and Department of Epidemiology and Biostatistics (E.V., M.J.P.), University of California San Francisco; Azumio Inc, San Francisco, CA (P.K.); and School of Public Health, Division of Community Heath and Human Development, University of California Berkeley, (K.A.M.). Jeffrey.Olgin@ucsf.edu.
Jeffrey E
JE
Olgin
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D000068997:Smartphone / Q000706:statistics & numerical data*; D013997:Time Factors; D016138:Walking / Q000502:physiology*; D055815:Young Adult
disease management; exercise test; heart failure; hypertension; mobile applications; pulmonary; smartphone; telemedicine