A Telemedicine Alternative to the 6-Minute Walk Test Using Personal Activity Trackers in Liver Transplant Candidates

Abstract

Liver TransplantationBackground. The COVID-19 pandemic has limited liver transplant (LT) candidates access to clinics. Telehealth methods to assess frailty are needed. We developed a method to estimate the step length of LT candidates, which would permit remotely obtaining the 6-min walk test (6MWT) distance with a personal activity tracker (PAT). Methods. 6MWT was performed while candidates wore a PAT. On first 21 subjects (stride cohort), the step length was measured and compared with calculated one (6MWT-distance/6MWT steps). On a second cohort (PAT-6MWT; n = 116), we collected the 6MWT step count and used multivariable models to generate formulas estimating step length. We multiplied the estimated step length times 6MWT steps to estimate the distance and compared it to the measured distance. The liver frailty index (LFI) and 6MWT were used as frailty metrics. Results. Measured/calculated step length were highly correlated (ρ = 0.85; P < 0.001) in the stride cohort. In the PAT-6MWT cohort, LFI was the strongest variable associated with step length, along with height, albumin, and large-volume paracentesis (R 2 = 0.58). On a second model without LFI, age, height, albumin, hemoglobin, and large-volume paracentesis were strongly associated with step length (R 2 = 0.45). There was a robust correlation between observed 6MWT and PAT-6MWT utilizing step length equations with (ρ = 0.80; P < 0.001) or without LFI (ρ = 0.75; P < 0.001). Frailty by 6MWT <250 m did not change significantly using the observed (16%) or the with/without LFI-estimated (14%/12%) methods. Conclusions. We created a method to obtain 6MWT distance remotely with the use of a PAT. This novel approach opens the possibility of performing telemedicine PAT-6MWT to monitor LT candidates' frailty status.

Emerging digital technologies to help patients with cirrhosis

“…In a 3-month study, the intervention led to improved frailty measures (liver frailty index, 6-minute walk test), including a third of patients transitioning from the frail to nonfrail state. [9] BIOMETRIC DATA…”

“…The EL-FIT application incorporates exercise video regimens, goal-oriented coaching, and physical activity tracking to modify frailty measures. In a 3-month study, the intervention led to improved frailty measures (liver frailty index, 6-minute walk test), including a third of patients transitioning from the frail to nonfrail state 9 …”

Deciphering an expanding array of clinical and research frailty measures

“…More recently, the Tele-Liver Frailty Index was developed to accurately measure frailty virtually, leveraging validated surveys (Duke Activity Status Index and SARC-F screen) and an optional remote physical assessment (ie, chair stands via videoconference call) 13 . Similarly, a telemedicine version of the 6MWT was recently developed and tested in a pilot study, demonstrating a robust correlation with the standard in-person 6MWT 14 . This remote assessment of aerobic capacity, coined the Tele-6MWT, utilizes a personal activity tracker and builds on past evidence, showing that daily step counts acquired by personal activity trackers correlate with frailty and predict worse clinical outcomes 15 .…”

Editorial: Enhancing frailty assessment in liver transplantation candidates—The role of the Duke Activity Status Index in predicting mortality and guiding prehabilitation

“…2 However, most predictive models fail to accurately capture physical frailty, which is common in LT candidates, 3 strongly predictive of poor clinical outcomes, 4 and can be reversed with exercise-based prehabilitation programmes. 5 While multiple tools, including the Liver Frailty Index (LFI), 4 accurately measure physical frailty, none is optimal. The LFI remains the most comprehensive and disease-specific physical frailty assessment tool for individuals with advCLD.…”