Affiliations: [a] Krannert School of Physical Therapy, University of Indianapolis, Indianapolis, IN, USA
| [b] Center for the Study of Sport and Exercise, Seattle University, Seattle, WA, USA
| [c] College of Health Science and School of Nursing, University of Indianapolis, Indianapolis, IN, USA
Correspondence:
[*]
Address for correspondence: Connie Fiems, University of Indianapolis, Krannert School of Physical Therapy, 1400 E. Hanna Avenue, Indianapolis, IN 46227, USA. Tel.: +1 317 788 2182; Fax: +1 317 788 3542; E-mail: Fiemsc@uindy.edu.
Abstract: BACKGROUND:The emergence of mobile technology allows the examination of balance through direct measures of postural sway in a cost-effective, convenient and portable fashion. However, there is insufficient evidence for use in populations with neurologic conditions. OBJECTIVES:1) To determine the test-retest reliability of the Sway Balance™ mobile application in measuring postural sway in individuals with Parkinson disease, 2) To examine the concurrent validity of Sway Balance™ with inertial measurement units and 3) To determine if Sway Balance™ scores can predict disease severity. METHODS:Thirty subjects with early stage idiopathic Parkinson disease completed three trials of two Sway Balance™ protocols while postural sway was simultaneously measured by two inertial measurement units and Sway Balance™, then repeated testing one week later. RESULTS:Sway Balance demonstrated high test-retest reliability for both protocols (ICC = 0.72 and 0.92) and good to excellent inverse correlation with the inertial measurement units across both protocols (ρ= –0.61– –0.92; p < 0.001). Sway Balance™ did not accurately predict disease severity. CONCLUSION:Sway Balance™ demonstrates strong test-retest reliability and concurrent validity with measures from inertial measurement units. Questions remain regarding the ability of Sway Balance™ to accurately characterize balance of individuals who demonstrate difficulty maintaining the test condition.
Keywords: Postural sway, Parkinson disease, mobile technology, balance, falls
