Multiple sclerosis (MS) is an immune-mediated disease characterized by inflammatory activity and a neurodegenerative process leading to disability progression. Progression independent of relapse activity (PIRA) accounts for most of the disability accumulated by people with MS (pwMS) (Lublin et al., 2022). PIRA can be present early in pwMS, precluding a worse outcome (Tur et al., 2023). However, assessment of the disease disability is based on neurological evaluation through the Expanded Disability Status Scale (EDSS) and magnetic resonance imaging (MRI) which display limitations in assessing PIRA. EDSS assessment is usually restricted to one or two follow-up visits every year, and so may not be capable of detect mild worsening, which can also be subjected to fluctuations.

Remote health monitoring through electronic devices allows continuous and objective patient assessment (Block et al., 2017; Block et al., 2019). Of all devices, smartphones are the most widely available, and so, different strategies have been explored for both active and passive monitoring (Montalban et al., 2022; Lam et al., 2021). Although active testing is easier to perform, previous experiences stated that retention rate diminishes through time of assessment (Pratap et al., 2020).

We developed an in-house application to passively assess the tapping speed (TS) of pwMS. The aim of this proof-of-concept study was to assess the reliability and validity of TS measured by this app, exploring the cross-sectional correlation of TS (measured by our application) with baseline disability status of pwMS.