Smart watch, smarter EDSS: Improving disability assessment in multiple sclerosis clinical practice

Background Patients' walking ability is critical for assessing the EDSS, the disability scale commonly used in MS clinical practice. Such assessment is usually based on patients' estimates or on the measures the neurologists observe during periodic visits. Objectives and methods We evaluated the agreement between patients' and neurologists' estimates of maximum walking ability and patients' mean maximum walking ability measured in their daily life through a GPS smartwatch, and assessed limitations of the current methods. Results Seventy-three patients with a median walking ability of 500 m (IQR 400–800) were enrolled in the study. The agreement between patients' estimates and GPS measurements was modest (ICC 0.29, 95% CIs 0.06–0.49) and was influenced by course of the disease, patients' mood and inaccuracy at estimating long distances. A better reliability was found between neurologists' and GPS measures (ICC 0.68, 95% CIs 0.53–0.78), but the variability increased for longer distances and was influenced by patients' depressive symptoms, fatigue and course of the disease. Conclusions This study showed a poor agreement between patients' and neurologists' estimates of maximum walking ability and patients' mean maximum walking ability measured in their daily life through a GPS smartwatch, with many factors affecting patient's and neurologists' estimates of the EDSS. The use of remote measurement technologies may provide a better understanding of the impact of MS in a patient's life.