Responsiveness of an activity tracker as a measurement tool in a knee osteoarthritis clinical trial (ACTIVe-OA study)

Abstract

Background: In osteoarthritis (OA) clinical trials, reliable and responsive outcome measures to document physical and functional improvements are limited. Objective: This study aimed to assess whether the use of an activity tracker in an OA clinical trial is a responsive measurement tool. Secondary objectives assessed feasibility and validity. Methods: We recruited 65 participants in a prospective cohort study nested in a placebo-controlled clinical trial of platelet-rich plasma injection in knee OA. Participants wore an activity tracker (Fitbit Flex 2), and a smartphone was preloaded with a mobile application (OApp) designed to monitor load rates as a surrogate of knee loading. Participants..