Objective Comparison of 2 mobile device measures of balance assessment using EQ and Sway balance systems.

Design Method-comparison study.

Setting Sports Medicine and Concussion Clinic.

Participants 70 individuals (25 males and 45 females (mean age: 37.8 ± 14.8, range: 13–65) with and without concussion or other neurological conditions (39 concussed vs. 31 non-neurologically injured, or healthy).

Interventions (or Assessment of Risk Factors) Participants performed Balance Error Scoring System (BESS) postures measured while holding the mobile device against their chest.

Outcome Measures Repeated-measure multivariate general linear model by subject and device. Absolute agreement 2-way mixed-effects model Intraclass Correlation Coefficient (ICC) over 2 repetitions.

Main Results EQ and Sway Balance were in statistical agreement for both healthy and concussed groups according to Spearman’s rho test of correlation (all participants r = 0.85, healthy r = 0.79, concussed r = 0.83, p<0.001). ICC for the cohort was = 0.87 (p<0.001). A Bland-Altman plot revealed a mean difference = -1.205714286863804, limits of agreement = (20.57048061187871, 18.15905203815111) and averages lying between 40.150 and 94.300. Wilcoxon signed ranks test failed to find a statistically significant difference between the results of each test (z = -1.958, based on negative ranks, p>0.05 2-tailed). Statistically significant poorer balance scores were measured in subjects with diagnosed concussion (p < 0.001).

Conclusions We found statistically significant equivalence of EQ Balance to Sway Balance with concussed patients scoring worse than healthy controls. Both mobile apps are easy to use and provide useful clinical information that might be used as a biomarker of balance.