Belen Valladares ^1,2* Robinson G. Kundert ² Johannes Pohl ³ Jeremia Held ⁴ Andreas R. Luft ^2,4 Janne M. Veerbeek ⁵ Meret Branscheidt ^2,4

• ¹ University of Zurich, Zürich, Switzerland
• ² Center for Neurology and Rehabilitation (CERENEO), Vitznau, Switzerland
• ³ Data Analytics and Rehabilitation Technology, Lake Lucerne Institute AG, Vitznau, Switzerland
• ⁴ Department of Neurology, University Hospital Zurich, Zürich, Zürich, Switzerland
• ⁵ Luzerner Kantonsspital, Lucerne, Switzerland

Introduction: Stroke-induced upper limb disabilities can be characterized by both motor impairments and activity limitations, commonly assessed using Fugl-Meyer Motor Assessment for Upper Extremity (FMMA-UE) and Action Research Arm Test (ARAT), respectively. The relationship between the two assessments during recovery is largely unstudied. Expectedly they diverge over time when recovery of impairment (restitution) plateaus, but compensation-driven improvements still occur. The objective of this study is to evaluate the alignment between FMMA-UE and ARAT in defining upper limb functional recovery categories by ARAT scores. We aimed to establish cut-off scores for both measures from the acute/early subacute, subacute and chronic stages of stroke recovery. Methods: Secondary analysis of four prospective cohort studies (acute/early subacute: n=133, subacute: n=113, chronic: n=92) stages post-stroke. Receiver operating characteristic curves calculated the area under the curve (AUC) to establish optimal FMMA-UE cut-offs based on predefined ARAT thresholds distinguishing five activity levels from no activity to full activity. Weighted kappa was used to determine agreement between the two assessments. We used minimally clinically important difference (MCID) and minimal detectable change (MDC95) for comparison. Results: FMMA-UE and ARAT scores showed no relevant divergence across all recovery stages. Results indicated similar cut-off scores in all recovery stages with variability below MCID and MDC95 levels. Cut-off scores demonstrated robust AUC values from .77 to .86 at every recovery stage. Only in highly functional patients at the chronic stage, we found a reduced specificity of .55. At all other times sensitivity ranged between .68 and .99 and specificity between .71 and .99. Weighted kappa at the acute/early subacute, subacute and chronic stages was .76, .83 and .81 respectively. Discussion: Our research shows a strong alignment between FMMA-UE and ARAT cut-off scores throughout stroke recovery, except among the subgroup of highly recovered patients at the chronic stage. Discrepancies in specificity potentially stem from fine motor deficits affecting dexterity outcomes that are not captured by FMMA-UE. Additionally, the high congruence of both measures suggests they are not suited to distinguish between restitution and compensation. Calling for more comprehensive assessment methods to better understand upper limb functionality in rehabilitation.