Association between daily life walking speed and frailty measured by a smartphone application: a cross-sectional study

OBJECTIVES: To assess whether frailty can be assessed using a smartphone and whether daily walking speed (DWS) is associated with frailty. DESIGN: Cross-sectional study. SETTING: Three prefectures (Kanagawa, Saitama and Tokyo) in Japan. PARTICIPANTS: The study enrolled 163 participants (65 in the robust group, 69 in the prefrailty group and 29 in the frailty group) by sending letters to house owners aged≥55 years. PRIMARY AND SECONDARY OUTCOME MEASURES: The participants downloaded the DWS measurement application on their smartphones, which measured the daily walking (DW) parameters (DWS, step length and cadence) and the Kihon checklist for frailty assessment. The differences in the DW parameters between the robust, prefrailty and frailty groups were examined using one-way analysis of variance. We conducted logistic regression analysis for the Crude model (each DW parameter), model 1 (adjusted for the number of steps) and model 2 (model 1+age, sex and the number of chronic diseases). RESULTS: DWS was marginally significantly slower in the frailty group than in the prefrailty and robust group (robust 1.26 m/s vs prefrailty 1.25 m/s vs frailty 1.19 m/s, p=0.060). Step length was significantly smaller in the frailty group than in the robust group (robust 66.1 cm vs prefrailty 65.9 vs frailty 62.3 cm, p<0.01). Logistic regression analysis for the three models revealed that DWS was significantly associated with frailty. CONCLUSIONS: DWS measured using the smartphone application was associated with frailty. This was probably due to the shorter step length and body height seen in frail individuals.