Reproducibility of quantifying Timed Up and Go test, measured with smartphone accelerometers in older people living in the community

Introduction Inertial Measurement Units (IMU) incorporated in smartphones can provide records that match registers obtained by laboratory instruments. This means that the use of smartphones would be feasible for recording three-dimensional kinematics parameters like velocity and acceleration, enabling more robust analyses, such as the Timed Up and Go (TUG) test, that assess the risk of falls older people (OP) living in the community. Method The study included 35 female OP, users of the Family Health Centres (CESFAM) Juan Pablo II and Corvallis from Antofagasta city, Chile. They were evaluated with the TUG, with linear and angular acceleration and velocity being recorded simultaneously using a smartphone equipped with a three-dimensional IMU. Using a computer macro application, the start and end time of each sub-stage of the test was determined by two independent observers. Reproducibility of the times of each sub-stage of TUG was assessed using the Intraclass Correlation Coefficient (ICC). Results The ICC gave values of 0.78 to 0.99, with an acceptable confidence interval, (0.45-1.00), thus providing a reproducible and reliable recording. Conclusions The reproducibility of the times of the sub-stages of TUG, recorded with inertial measurement units from a smartphone enables it to be used in clinical practices with OP groups, in order to improve the evaluation and prevention of the risk of falls.