PD1007 - MID-UPPER ARM CIRCUMFERENCE CUT-OFF VALUES FOR LOW MUSCLE MASS AND ASSOCIATION WITH FUNCTIONAL OUTCOMES IN OLDER REHABILITATION PATIENTS

PD1007

MID-UPPER ARM CIRCUMFERENCE CUT-OFF VALUES FOR LOW MUSCLE MASS AND ASSOCIATION WITH FUNCTIONAL OUTCOMES IN OLDER REHABILITATION PATIENTS

A. Brown^1,2,*, T. Inoue², K. Amakasu^2,3, A. Saito^2,4, N. Kamada⁵, A. Kasai^2,6, M. Furusawa², H. Yanagida⁷, S. Kobayashi², Y. Wakunami⁸

¹Department of Nutrition, Kitanakagusuku Wakamatsu Hospital, Okinawa, ²Graduate School of Health and Welfare, Niigata University of Health and Welfare, ³Department of Rehabilitation, Shinrakuen Hospital, ⁴Department of Nutrition, Yoshida Hospital, Niigata, ⁵Department of Rehabilitation, Nippon Medical School Hospital, Tokyo, ⁶Department of Prevention and Care Science, Research Institute, National Center for Geriatrics and Gerontology, Aichi, ⁷Department of Rehabilitation, Jiseikai-Nerimatakanodai Hospital, Tokyo, ⁸Department of Internal Medicine, Kitanakagusuku Wakamatsu Hospital, Okinawa, Japan

Rationale: Mid-upper arm circumference (MUAC) may be a useful alternative for assessing muscle mass when bioelectrical impedance analysis (BIA) and other methods may not be feasible. However, evidence regarding MUAC cut-off values in Japanese rehabilitation patients remains limited. This study aimed to determine MUAC cut-off values and examine their association with functional outcomes.

Methods: This two-center prospective observational study included patients aged ≥65 years who were admitted to rehabilitation wards between May 2025 and February 2026. Low muscle mass was defined as the lowest quartile of fat-free mass index (FFMI) measured by bioelectrical impedance analysis (BIA) within our study population. Receiver operating characteristic (ROC) analysis was used to determine optimal MUAC cut-off values. Multivariable regression analysis examined the associations of MUAC-defined malnutrition and MUAC-defined low muscle mass with motor Functional Independence Measure (FIM) at discharge.

Results: A total of 143 patients (median age 84 years; 62.9% women) were analyzed. Musculoskeletal disorders were most common (72.7%), followed by cerebrovascular diseases (21.7%). MUAC correlated with FFMI in both men (r = 0.686) and women (r = 0.561). MUAC cut-off values were 25.0 cm in men and 24.2 cm in women based on the lowest FFMI quartile (AUC 0.871, 0.698). Sensitivity and specificity were 100% and 65.9% in men; 81.8% and 52.9% in women. These cut-off values were set at <25 cm in men and <24 cm in women for clinical use. MUAC-defined malnutrition was independently associated with motor FIM at discharge (β = −5.79, p = 0.009), whereas MUAC-defined low muscle mass was not associated (β = −1.75, p = 0.350).

Conclusion: MUAC may be a practical alternative for assessing muscle mass when BIA and other methods may not be feasible and may be associated with functional outcomes at discharge.

Disclosure of Interest: None declared