Associations between body mass index, mid-arm circumference, calf circumference, and functional ability over time in an elderly Taiwanese population

BACKGROUND Anthropometric measurements such as body mass index (BMI), mid-arm circumference (MAC), and calf-circumference (CC) are assessed with ease during regular health visits, but the associations between these anthropometric parameters and functional ability in elderly population over time has not been studied in detail. This study aimed to examine the associations between functional ability and the anthropometric parameters BMI, MAC, and CC in Taiwanese adults ≥ 65 years old. METHODS Data were obtained from the Taiwan Longitudinal Study of Aging and analyzed retrospectively. RESULTS Functional decline over a 4- and 8-year period was noted in approximately 14% and 21% of study participants, respectively. BMI was negatively associated with participants' current Activities of Daily Living (ADL) scores, and was positively associated with 4-year ADL scores in adults ≥ 65 years old (β = -1.19 and 1.14, P = 0.0010 and 0.0420, respectively). MAC and CC were negatively associated with current ADL scores (β = -1.46, P < 0.0001 and β = -4.68, P < 0.0001, respectively). The association between CC and current ADL score was stronger than the association between current ADL score and either BMI or MAC. For adults ≥ 65 years old, a high BMI increased the risk of ADL decline over 4 and 8 years by 4-fold and 3-fold (adjusted odds ratio = 4.23 and 2.64, 95% confidential interval = 1.95-9.19 and 1.22-5.71, P = 0.0003 and 0.0141, respectively). CONCLUSIONS BMI is a significant predictor of decline of functional ability in Taiwanese adults ≥ 65 years old. CC is an important anthropometric indicator of current functional ability among older adults.