Connecting real-world digital mobility assessment to clinical outcomes for regulatory and clinical endorsement–the Mobilise-D study protocol
Authors: Mikolaizak A. Stefanie , Rochester Lynn , Maetzler Walter , Sharrack Basil , Demeyer Heleen , Mazzà Claudia , Caulfield Brian , Garcia-Aymerich Judith , Vereijken Beatrix , Arnera Valdo , Miller Ram , Piraino Paolo , Ammour Nadir , Gordon Mark Forrest , Troosters Thierry , Yarnall Alison J. , Alcock Lisa , Gaßner Heiko , Winkler Jürgen , Klucken Jochen , Schlenstedt Christian , Watz Henrik , Kirsten Anne-Marie , Vogiatzis Ioannis , Chynkiamis Nikolaos , Hume Emily , Megaritis Dimitrios , Nieuwboer Alice , Ginis Pieter , Buckley Ellen , Brittain Gavin , Comi Giancarlo , Leocani Letizia , Helbostad Jorunn L. , Johnsen Lars Gunnar , Taraldsen Kristin , Blain Hubert , Driss Valérie , Frei Anja , Puhan Milo A. , Polhemus Ashley , Bosch de Basea Magda , Gimeno Elena , Hopkinson Nicholas S. , Buttery Sara C. , Hausdorff Jeffrey M. , Mirelman Anat , Evers Jordi , Neatrour Isabel , Singleton David , Schwickert Lars , Becker Clemens , Jansen Carl-Philipp ,   and members of the clinical validation study (WP4) on behalf of Mobilise-D consortium
Published: October 2022

Background
The development of optimal strategies to treat impaired mobility related to ageing and chronic disease requires better ways to detect and measure it. Digital health technology, including body worn sensors, has the potential to directly and accurately capture real-world mobility. Mobilise-D consists of 34 partners from 13 countries who are working together to jointly develop and implement a digital mobility assessment solution to demonstrate that real-world digital mobility outcomes have the potential to provide a better, safer, and quicker way to assess, monitor, and predict the efficacy of new interventions on impaired mobility. The overarching objective of the study is to establish the clinical validity of digital outcomes in patient populations impacted by mobility challenges, and to support engagement with regulatory and health technology agencies towards acceptance of digital mobility assessment in regulatory and health technology assessment decisions.

Methods/design
The Mobilise-D clinical validation study is a longitudinal observational cohort study that will recruit 2400 participants from four clinical cohorts. The populations of the Innovative Medicine Initiative-Joint Undertaking represent neurodegenerative conditions (Parkinson’s Disease), respiratory disease (Chronic Obstructive Pulmonary Disease), neuro-inflammatory disorder (Multiple Sclerosis), fall-related injuries, osteoporosis, sarcopenia, and frailty (Proximal Femoral Fracture). In total, 17 clinical sites in ten countries will recruit participants who will be evaluated every six months over a period of two years. A wide range of core and cohort specific outcome measures will be collected, spanning patient-reported, observer-reported, and clinician-reported outcomes as well as performance-based outcomes (physical measures and cognitive/mental measures). Daily-living mobility and physical capacity will be assessed directly using a wearable device. These four clinical cohorts were chosen to obtain generalizable clinical findings, including diverse clinical, cultural, geographical, and age representation. The disease cohorts include a broad and heterogeneous range of subject characteristics with varying chronic care needs, and represent different trajectories of mobility disability.

Discussion
The results of Mobilise-D will provide longitudinal data on the use of digital mobility outcomes to identify, stratify, and monitor disability. This will support the development of widespread, cost-effective access to optimal clinical mobility management through personalised healthcare. Further, Mobilise-D will provide evidence-based, direct measures which can be endorsed by regulatory agencies and health technology assessment bodies to quantify the impact of disease-modifying interventions on mobility.

Trial registration
ISRCTN12051706.