Rater reliability and construct validity of a mobile application for posture analysis.
Kimberly A Szucs, Elena V Donoso Brown
PMID 29410561WHAT IT FOUND
With reflective markers and minimal clothing, the posture app gave consistent measurements between raters and detected expected head changes plus an unexpected shoulder shift in healthy young adults while they texted or called.
Key findings
01Rater 1 intra-rater ICCs ranged from 0.76 to 0.99, average 0.93; rater 2 intra-rater ICCs ranged from 0.71 to 0.99, average 0.92.
02Inter-rater ICCs averaged 0.95 for translations and 0.88 for angulations.
03The app showed statistically significant differences across standing, texting, and phone call for all four head variables and for shoulder right lateral translation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample was only 20 healthy young volunteers with no shoulder, neck, or back pathology, so the results may not apply to clinical patients. Reliability was tested only for digitizing the same photos, not for the whole process of taking, cropping, and retesting posture over time. Camera height was adjusted for each subject rather than standardized, which could add error. Only 20 of the app's 39 variables were analysed for reliability, and validity analyses included 18 to 20 participants per variable because outliers were removed. The study did not compare the app with an advanced camera system or test concurrent validity.
Declared interests
The authors declared no conflicts of interest, and the research did not receive a specific grant from public, commercial, or not-for-profit sectors.
The easy way to misread this
Do not conclude the app is validated for patient populations or can replace goniometry. It was tested in 20 healthy young volunteers, and the study did not assess full test-retest reliability or concurrent validity with a 3-D system.