Smartphone accelerometry to assess postural control in individuals with multiple sclerosis

Abstract

BackgroundFalls are a major health concern for people with Multiple Sclerosis (pwMS), and impaired postural control is an important predictor of falls. Lab-based technology to measure posture is precise but expensive, and clinical tests may not capture underlying impairments. An alternative solution is to leverage smartphone accelerometry as it is affordable, ubiquitous, and portable. Research question: Can smartphone accelerometry measure postural control compared to a force plate and research grade accelerometer in pwMS, and can smartphone accelerometry discriminate between assisted device and non-assisted device users? Methods27 pwMS (12 assisted device users, 15 non-assisted device users) stood on a force plate while holding a smartphone with an attached research grade accelerometer against their chest. Participants performed two, 30 s trials of: eyes open, eyes closed, semi-tandem, tandem, and single leg. Acceleration and center of pressure were extracted, and Root Mean Square (RMS) and 95 % confidence ellipse were calculated. Spearman’s correlations were performed, and receiving operating characteristic (ROC) curves and the Area Under the Curve (AUC) were calculated. ResultsThere were moderate to high correlations between the smartphone and accelerometer for RMS (ρ = 0.85 – 1.0; p = 0.001 – <0.001) and 95 % area ellipse (ρ = 0.92 – 0.99; p = <0.001). There were weak to moderate correlations between the smartphone and force plate for RMS (ρ = 0.38 – 0.92; p = 0.06 – <0.001) and 95 % area ellipse (ρ = 0.69 – 0.90 p = 0.002 – <0.001). To discriminate between assisted device usage, ROC curves for smartphone outputs were constructed, the AUC was high and statistically significant (p < 0.001 – 0.02). SignificanceThere is potential to leverage smartphone accelerometery to measure postural control in pwMS. These finding provide preliminary results to support the development of a mobile health application to measure fall risk for pwMS.