JMIR Publications

ABSTRACT

Background:

Recent studies demonstrated the validity, reliability and accuracy of consumer smartwatches for measuring daily steps in people with Parkinson’s disease (PwPD). However, no study to date estimated the minimal clinically important difference (MCID) for average daily steps (avDS), measured through a consumer smartwatch in PwPD.

Objective:

To calculate the MCID of avDS, measured through a commercial smartwatch (Garmin Vivosmart 4) in PwPD.

Methods:

PwPD with a disease stage <4, without cognitive impairment able to walk unaided wore a Garmin Vivosmart 4 smartwatch for 5 consecutive days on the wrist least affected by the disease allowing the computation of avDS. To define three levels of MCID for avDS, we used an anchor-based method linked to: i) scales capturing subtle changes in global mobility and motor functions; ii) clinical and health-related measures; and iii) disease-related patient reported outcomes (PROs). Linear regressions, Student t-test and ANOVA were used to estimate the minimal change in avDS based on anchors relevant change. For each level, overall MCID was calculated as the average of the variables included and range was reported.

Results:

A total of 100 PwPD were enrolled. Participants took on average 5949±3034 daily steps ranging from 357 to 12620. MCID of avDS anchored to standardized measures of motor symptoms and mobility was 581 steps/day (range: 554–608) or around 10% of mean avDS in our population. MCID of avDS anchored to clinical and health-related variables was 1200 steps/day (range: 350-1683), or around 20% of mean avDS average in our population. Finally, MCID of avDS anchored to disease-related PROs was 1592 steps/day (range: 594-2589), or around 27% of the mean avDS in our population.

Conclusions:

These findings could be relevant for designing future clinical trials involving avDS as a digital mobility outcome in daily life in PwPD and evaluating the effectiveness of intervention promoting free-living walking in this population.