5 Minute Poster Presentation ARA-NSW 2020 - 42nd Annual NSW Branch Meeting

Responsiveness of an activity tracker as a measurement tool in knee osteoarthritis clinical trial (ACTIVe-OA Trial) (#21)

Shirley P Yu 1 , Manuela Ferreira 1 , Vicky Duong 1 , Jimmy Caroupapoulle 2 , Nigel K Arden 3 4 , Kim L Bennell 5 , David J Hunter 1
  1. Department of Rheumatology, Kolling Institute, Royal North Shore Hospital and Institute of Bone and Joint Research University of Sydney, Sydney, New South Wales, Australia
  2. Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, United Kingdom
  3. Centre for Sport, Exercise and Osteoarthritis Versus Arthritis, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
  4. MRC Lifecourse Epidemiology Unit, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
  5. Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Faculty of Medicine Dentistry & Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia

Objective

In osteoarthritis (OA) clinical trials, reliable and responsive outcome measures to document functional improvements are limited. The aim was to assess if the use of an activity tracker in an OA clinical trial is a responsive measurement tool. Secondary objectives were to assess the feasibility and validity of an activity tracker in an OA clinical trial context.

 Methods

In a prospective cohort study nested in a clinical trial of platelet rich plasma injection in knee OA – the RESTORE trial, participants wore an activity tracker (Fitbit Flex (2)), for seven days at baseline prior to a series of 3 knee injections of either PRP or saline and at 2-months of follow-up. Participants’ knee loading rate was captured using a smartphone (Samsung Galaxy A5TM) with a pre-loaded, mobile application (OAppTM).

 Results

65 participants were recruited (mean age = 61.3 years; 46% female; mean BMI 28.7 kg/m2). Step count had a trivial effect size (ES) and standardised response mean (SRM) and mean knee loading rate measurements showed moderate ES and SRM in comparison to currently utilised outcome measures. A weak but significant correlation between change in mean steps per day and global improvement overall (r=0.28) and WOMAC function (r=-0.28) was demonstrated. Compliance was high with the activity trackers.

 Conclusions

Our study showed that the use of activity trackers is a feasible option in a clinical trial context as an outcome measurement tool. However, this study has shown limited responsiveness. One of the main challenges of this study is the lack of a gold standard outcome measure to validate against. Due to the complex nature of pain, perceived quality of life and the interplay between these factors and measured function, a lack of correlation does not necessarily represent a failed validation in this context. Further larger sample studies with possibly longer duration of activity tracker wear are required to validate activity tracker measurements as an outcome measure.