Reliability and repeatability of a smartphone-based 6-min walk test as a patient-centred outcome measure

Abstract

Background The 6-Mniute-Walk-Test (6MWT) is a validated proxy for frailty and a predictor of clinical outcomes, yet is not widely used due to implementation challenges. This comparative effectiveness study assesses the reliability and repeatability of a home-based 6MWT compared to in-clinic 6MWTs in patients with cardiovascular disease. Methods One hundred and ten (110) patients scheduled for cardiac or vascular surgery were enrolled during a study period from June 2018 to December 2019 at the Palo Alto VA Hospital. Subjects were provided with an Apple iPhone 7 and Apple Watch Series 3 loaded with the VascTrac research study application and performed a supervised in-clinic 6MWT during enrollment, at two weeks, one, three, and six months post-operatively. Subjects also received notifications to perform at-home smartphone-based 6MWTs once a week for a duration of six months. Test-retest reliability of in-clinic measurements and at-home measurements was assessed with an industry standard Cronbach’s alpha reliability test. Results Test-Retest Reliability for in-clinic ground truth 6MWT steps vs. in-clinic iPhone 6MWT steps was 0·99, showing high reliability between the two tested measurements. When comparing for in-clinic ground truth 6MWT steps vs. neighboring at-home iPhone 6MWT steps, reliability was 0·74. Conclusion Running the test-reliability test on both measurements shows that an iPhone 6MWT test is reliable compared to an in-clinic ground truth measurement in patients with cardiovascular disease.

Cardiac Effort to Compare Clinic and Remote 6-Minute Walk Testing in Pulmonary Arterial Hypertension

“…The traditional 6MWT is staff supervised within an unobstructed 30-m hallway 22 ; especially indoors, most patients will not be able to replicate this hallway at home. Others have reported different strategies for remote 6MWT including algorithms developed to estimate walk distance based on wearables 20,25 or smartphones 19,[25][26][27][28] ; global positioning system (GPS)-enabled devices can estimate walk distance outdoors, 19,29 and LaPatra et al 12 used remote observation. These different approaches were tested in a wide variety of individuals including healthy control subjects 27 and patients with strokes, 29 pulmonary hypertension, 12 peripheral vascular disease, 26 and coronary artery disease 26 ; the courses were also variable.…”

“…Others have reported different strategies for remote 6MWT including algorithms developed to estimate walk distance based on wearables 20,25 or smartphones 19,[25][26][27][28] ; global positioning system (GPS)-enabled devices can estimate walk distance outdoors, 19,29 and LaPatra et al 12 used remote observation. These different approaches were tested in a wide variety of individuals including healthy control subjects 27 and patients with strokes, 29 pulmonary hypertension, 12 peripheral vascular disease, 26 and coronary artery disease 26 ; the courses were also variable. All of the different methods showed high agreement between estimated and directly measured 6MWT distance, performed at about the same time.…”

Effects of COVID-19 Acute Respiratory Distress Syndrome Intensive Care Unit Survivor Telemedicine Clinic on Patient Readmission, Pain Perception, and Self-Assessed Health Scores: Randomized, Prospective, Single-Center, Exploratory Study

“…The 6MWT is a functional capacity assessment method for patients with cardiopulmonary conditions usually performed in a pulmonary function laboratory. Mak et al [ 18 ] used iPhones and Apple Watches to measure the reliability of the 6MWT performed outside the laboratory. For patients performing an in-clinic 6MWT, the researchers noted an error between ground truth and phone-calculated steps ranging from 2.0% to 8.0% [ 18 ].…”

“…Mak et al [ 18 ] used iPhones and Apple Watches to measure the reliability of the 6MWT performed outside the laboratory. For patients performing an in-clinic 6MWT, the researchers noted an error between ground truth and phone-calculated steps ranging from 2.0% to 8.0% [ 18 ]. Our study used the 6MWT as a surrogate marker of functional impairment following hospitalization.…”

Repeatability and learning effect in the 6MWT in preoperative cancer patients undergoing a prehabilitation program

“…Over the past decades, as a result of a noticeable growth in the eld of oncology rehabilitation and exercise, the use of the 6MWT has increased in this population although studies on its test-retest reliability are scarce [7]. In patients with cardiorespiratory diseases where the 6MWT has been most widely applied, the test-retest reliability was found to be excellent with intra-class correlation coe cients (ICC) ranging from 0.88 to 0.99 [8][9][10][11][12]. However, despite this high correlation, most studies have reported improvements in the distance covered during the second test, indicating the existence of a learning effect which has led to a recommendation of performing a re-test [9,13].…”