Open Access

Marcus Grobe‐EinslerORCiD, Vivian Maas, Arian Taheri Amin, Jennifer Faber, Tamara Schaprian, Katharina Hill, Matthis SynofzikORCiD, Lisa Graf, Heike JacobiORCiD, Manuela Lima, Ana Ferreira, Bart van de Warrenburg, Ilse Willemse, Dagmar Timmann, Andreas Thieme, Paola Giunti, Hector Garcia‐Moreno, Magda Santana, Jeannette Hübener‐SchmidORCiD, Elin Davies, Thomas Klockgether

• Objective Spinocerebellar ataxia type 3 (SCA3) is a genetically defined ataxia. The Scale for Assessment and Rating of Ataxia (SARA) is a clinician‐reported outcome that measures ataxia severity at a single time point. In its standard application, SARA fails to capture short‐term fluctuations, limiting its sensitivity in trials. To overcome this, we employed SARAhome, a video‐based, self‐administered tool for high‐frequency, remote ataxia assessment. Methods We assessed feasibility and validity of SARAhome in 65 SCA3 patients from seven centers. Participants recorded SARAhome twice daily for 14 days using a mobile e‐health app. We analyzed adherence, intraindividual fluctuations and their predictors, and evaluated sensitivity to change in a longitudinal substudy of 11 patients. Results Adherence to the study protocol was generally high (80.2%) with valid scores in 79.2% of 1459 recordings. Maximum adherence occurred over a 4‐day period (84.8%). Fluctuations ranged 3.0 points between lowest and highest scores (IQR: 2.5–4.5) and 1.0 point based on score IQRs (IQR: 0.5–1.5), corresponding to 10.7% and 3.6% of the maximal SARAhome score. Fluctuations showed rough agreement with patient global impression. Greater disease severity and longer CAG repeats were associated with smaller relative fluctuations. Over a median follow‐up of 411 days, SARAhome showed higher sensitivity to change than conventional SARA (SRM: 0.67 vs. 0.37). Interpretation SARAhome is a feasible, innovative video‐based tool for remote, high‐frequency monitoring of ataxia severity. A 4‐day recording effectively captures relevant fluctuations and enhances sensitivity to change, supporting its use in future SCA3 trials.