JMIR Publications

ABSTRACT

Background:

Kidney transplant candidates frequently experience declining physical function and frailty while awaiting transplantation. Although standardized functional assessments are routinely incorporated into transplant evaluation, they are generally limited to in-person clinic visits, creating challenges for longitudinal monitoring. Mobile health technologies may facilitate remote assessment of physical function; however, transplant-specific applications remain limited.

Objective:

The objective of this study was to develop and conduct a pilot evaluation of FIT Kidney, a transplant-specific mobile health application designed for remote assessment of physical function, and to evaluate its measurement agreement with standardized observer-based assessments and its usability among kidney transplant candidates.

Methods:

We conducted a single-center pilot study involving 24 adult kidney transplant candidates undergoing standardized physical function assessment. Participants completed the Sit-to-Stand (STS), Six-minute walk test (6MWT), and Timed-up-and-Go (TUG) while measurements were simultaneously recorded by FIT Kidney and trained observers. Agreement between application-derived and observer-derived measurements was evaluated using paired statistical testing, intraclass correlation coefficients (ICCs), Lin concordance correlation coefficients (CCCs), and Bland-Altman analyses. User experience was assessed using the User Experience Questionnaire (UEQ).

Results:

Twenty-four participants (13 women and 11 men; mean age 61.0, SD 10.2 years; mean body mass index 27.4, SD 4.7 kg/m²) were enrolled. 22 participants completed the STS, 19 completed the 6MWT, and 18 completed the TUG. FIT Kidney demonstrated excellent agreement with observer measurements for the STS (ICC=0.945; CCC=0.943; P=.06) and 6MWT (ICC=0.956; CCC=0.954; P=.32). For the TUG, the application systematically overestimated completion time compared with observer assessment but maintained good agreement (ICC=0.794; CCC=0.794; P<.001). Participants reported positive usability ratings across UEQ domains of attractiveness, perspicuity, efficiency, dependability, and stimulation, while novelty received a neutral rating.

Conclusions:

This pilot study demonstrated that FIT Kidney achieved favorable measurement agreement with observer-based assessment for selected functional performance measures while receiving positive usability evaluations from kidney transplant candidates. These findings support the feasibility of transplant-specific mobile health technology for remote assessment of physical function. Larger multicenter studies conducted in home-based settings are needed to evaluate longitudinal performance, implementation, and potential integration into transplant care pathways. Clinical Trial: This study was approved by the University of British Columbia Institutional Review Board (H19-01405-A015).