Evaluation of the 6-minute walking test as a smartphone app-based self-measurement of objective functional impairment in patients with lumbar degenerative disc disease.

Abstract

OBJECTIVE:

Digital transformation enables new possibilities to assess objective functional impairment (OFI) in patients with lumbar degenerative disc disease (DDD). This study examines the psychometric properties of an app-based 6-minute walking test (6WT) and determines OFI in patients with lumbar DDD.

METHODS:

The maximum 6-minute walking distance (6WD) was determined in patients with lumbar DDD. The results were expressed as raw 6WDs (in meters), as well as in standardized z-scores referenced to age- and sex-specific values of spine-healthy volunteers. The 6WT results were assessed for reliability and content validity using established disease-specific patient-reported outcome measures.

RESULTS:

Seventy consecutive patients and 330 volunteers were enrolled. The mean 6WD was 370 m (SD 137 m) in patients with lumbar DDD. Significant correlations between 6WD and the Core Outcome Measures Index for the back (r = -0.31), Zurich Claudication Questionnaire (ZCQ) symptom severity (r = -0.32), ZCQ physical function (r = -0.33), visual analog scale (VAS) for back pain (r = -0.42), and VAS for leg pain (r = -0.32) were observed (all p < 0.05). The 6WT revealed good test-retest reliability (intraclass correlation coefficient 0.82), and the standard error of measurement was 58.3 m. A 4-tier severity stratification classified patients with z-scores > -1 (no OFI), -1 to -1.9 (mild OFI), -2 to -2.9 (moderate OFI), and ≤ -3 (severe OFI).

CONCLUSIONS:

The smartphone app-based self-measurement of the 6WT is a convenient, reliable, and valid way to determine OFI in patients with lumbar DDD. The 6WT app facilitates the digital evaluation and monitoring of patients with lumbar DDD.

• Authors: Nicolai Maldaner, Marketa Sosnova, Anna M Zeitlberger, Michal Ziga, Oliver P Gautschi, Luca Regli, Astrid Weyerbrock, Martin N Stienen, International 6WT Study Group
• Journal: Journal of neurosurgery. Spine (J Neurosurg Spine) Vol. 33 Issue 6 Pg. 779-788 (08 07 2020) ISSN: 1547-5646 [Electronic] United States
• PMID: 32764182 (Publication Type: Journal Article)

Topics

• Diagnostic Self Evaluation
• Disability Evaluation
• Female
• Humans
• Intervertebral Disc Degeneration (physiopathology)
• Lumbar Vertebrae (physiopathology)
• Male
• Middle Aged
• Mobile Applications
• Patient Reported Outcome Measures
• Psychometrics
• Reproducibility of Results
• Smartphone
• Walk Test