Poster Presentation 51st International Society for the Study of the Lumbar Spine Annual Meeting 2025

Criterion Validity of ActiGraph (GT9X) device step count in adults with chronic low back pain (#204)

Meenakshi Sundaram 1 , Zakiy Alfikri 1 , Cristiane Carlesso 1 , Matt Mowacoski 1 , Corey Flynn 1 , Carol M Greco 1 , John Jakicic 2 , Sara R Piva 1
  1. University of Pittsburgh, Pittsburgh, PENNSYLVANIA, United States
  2. Kansas State University Medical Center, Kansas City, Kansas, United States

Introduction

Chronic low back pain (cLBP) is a leading cause of global disability.(1, 2) Clinical guidelines recommend physical activity to manage cLBP.(3, 4) Hence, having a valid measure to reliably assess step counts is important. ActiGraph GT9X is an accelerometer shown to be reliable in healthy individuals but reduced accuracy in older adults with mobility deficits.(5) In cLBP, gait characteristic are altered,(6) which could influence the step counts assessed by the GT9X.  Hence, the aim of this study was to assess the criterion validity of ActiGraph GT9X by comparing the visual step counts from trained health professionals to the device step count using associated normal-frequency (NF) and low-frequency extension (LFE) filtering algorithms in individuals with cLBP.

Methods

A convenience sample of 44 adults participating in a large cLBP cohort study (1U19AR076725-01) were included in this validity study. This ancillary cross-sectional study was administered during 15-20 minutes of the physical testing of the parent study. The protocol assessed the steps taken during ambulatory activities (2-min fast walk, 2-min slow walk, brief ambulation during 4-m walk test or walking between tasks), and non-ambulatory activities (lifting boxes and standing balance tests). Participants wore the ActiGraph throughout the protocol and two physical therapists counted the steps using a manual tally counter, which served as the reference standard. A two-way mixed model inter-class correlational (ICC2,1) coefficient with 95% confidence interval assessed the consistency of the manual tally step counts and the ActiGraph normal frequency (NF) and low frequency extension (LFE). The ICC has values between 0 and 1, where values below 0.5 indicate poor reliability, between 0.5 and 0.75 moderate reliability, between 0.75 and 0.9 good reliability, and any value above 0.9 indicates excellent reliability.(7) 

Results

The 44 participants’ mean age was 56.7 (SD=16.1) years; 61.4% were female, with Oswestry Disability Index (ODI) of 32.9 (SD=11.7) and pain rating of 5.8 (SD= 1.8) on a 0-10 scale. The average number of steps for ambulatory and non-ambulatory activities were 643 and 38 counts respectively. The consistency (ICC values [95% CI]) when comparing manual and LFE counts was good (0.77 [0.57; 0.88]) for ambulatory activities and moderate (0.70 [0.40; 0.84]) for non-ambulatory activities. Among the ambulatory activities, we observed good consistency for 2-min fast walk (0.78 [0.57; 0.88]) and brief ambulation (0.75 [0.48; 0.87]), and moderate consistency for the 2-min slow walk (0.68 [0.37; 0.83). There was good consistency (0.83 [0.69; 0.91]) comparing manual and LFE when combining ambulatory and non-ambulatory step counts. The consistency comparing manual and NF step counts was poor for all activities (ICCs from 0.29 to 0.45).

Discussion

There was moderate to good consistency for the overall protocol using the LFE algorithm for step counts consistent with other studies. The LFE step counts demonstrated superior consistency for activities involving fast ambulation compared to slow ambulation or non-ambulatory activities. There was poor consistency using the NF algorithm in cLBP. In cLBP patients, the ActiGraph GT9X device can provide reliable quantifiable step counts when the LFE algorithm is used, but not the NF algorithm.

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