Digital biomarkers can highlight subtle clinical differences in radiologically isolated syndrome compared to healthy controls

Abstract

Background: The aim of our study was to explore the use of digital biomarkers to distinguish healthy controls (HCs) from patients with radiologically isolated syndrome (RIS). Methods: We developed a smartphone application called MS Screen Test (MSST) to explore several dimensions of the neurological examination such as finger tapping speed, agility, hand synchronization, low contrast vision and cognition during a short evaluation. This application was tested on a cohort of healthy volunteers, including a subset of HCs who underwent two evaluations on the same day to assess reproducibility. In a second step, the application was tested in patients with RIS, and their performances were compared with age- and gender-matched HCs. Results: Thirty-seven HCs underwent two consecutive evaluations on MSST, which showed good reproducibility for all measures. Then, the findings from 21 patients with RIS were compared with those from 32 matched HCs. Compared with HCs, patients with RIS had a lower finger tapping speed on the dominant hand (5.6 versus 6.5 taps/s; p=0.005), a longer inter-hand interval during the hand synchronization task (14.4 versus 11.3 ms; p=0.03) and significantly poorer scores on the low contrast vision and cognition tests. Conclusion: MSST requires only a smartphone to obtain digital biomarkers related to several dimensions of the neurological examination. Our results highlighted subtle differences between HCs and patients with RIS. We plan to evaluate this tool in MS patients, which will allow a much larger sample of patients, to determine whether digital biomarkers can predict disease course.