Background and purpose Assessing patients’ disability in multiple sclerosis (MS) requires time‐consuming batteries of hospital tests. MSCopilot is a software medical device for the self‐assessment of patients with MS (PwMS), combining four tests: walking, dexterity, cognition and low contrast vision. The objective was to validate MSCopilot versus the Multiple Sclerosis Functional Composite (MSFC). Methods This multicentre, open‐label, randomized, controlled, crossover study enrolled 141 PwMS and 76 healthy controls (HCs). All participants performed MSCopilot and MSFC tests at day 0. To assess reproducibility, 46 PwMS performed the same tests at day 30 ± 3. The primary end‐point was the validation of MSCopilot versus MSFC for the identification of PwMS against HCs, quantified using the area under the curve (AUC). The main secondary end‐point was the correlation of MSCopilot z‐scores with MSFC z‐scores. Results In all, 116 PwMS and 69 HCs were analysed. The primary end‐point was achieved: MSCopilot performance was non‐inferior to that of MSFC (AUC 0.92 and 0.89 respectively; P = 0.3). MSCopilot and MSFC discriminated PwMS and HCs with 81% and 76% sensitivity and 82% and 88% specificity respectively. Digital and standard test scores were highly correlated (r = 0.81; P < 0.001). The test–retest study demonstrated the good reproducibility of MSCopilot. Conclusion This study confirms the reliability of MSCopilot and its usability in clinical practice for the monitoring of MS‐related disability.

These findings confirm recent AIS studies. Our results might be related to immature central integration of dynamic proprioceptive input leading to a poorly adapted motor response, particularly for postural control of the, in AIS. These balance tests can be performed in routine practice. Their validity as a biomarker for screening and monitoring purposes should be assessed.

There is not enough evidence to show a link between unilateral, isolated, vestibular dysfunction and AIS. From these findings, we propose a more global pathophysiological concept, which involves a trouble of the orthostatic postural control, with disturbance in the multisensory integration of vestibular, visual and somesthesic inputs. AIS could be the consequence of a reorientation of the longitudinal body axis in accordance with an erroneous central representation of verticality. An assessment of the sense of verticality would allow evaluate this hypothesis.