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

Date Published: April 11, 2017

Publisher: Public Library of Science

Author(s): Hsin-Jen Tsai, Fu-Kuei Chang, Gianluigi Forloni.

http://doi.org/10.1371/journal.pone.0175062

Abstract

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.

Data were obtained from the Taiwan Longitudinal Study of Aging and analyzed retrospectively.

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). 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.

Partial Text

Taiwan is one of the most rapidly aging societies in the world. The proportion of adults ≥ 65 years old was 11% in 2010, and is expected to reach 20% in 2025 [1, 2]. As a consequence, aging and aged-related issues have become a public health concern. In 2013, the World Health Organization highlighted the importance of frailty in an aging society [3]. Frailty in the elderly is related to aging, functional disability and comorbidity [4]. One of the major phenotypes of frailty in older adults is a loss of their ability to independently perform activities of daily living (ADLs) [5, 6]. It is estimated that close to 15% of elderly adults ≥ 70 years old experience some limitation in their ability to perform ADLs [7], and this increases to up to 46% in institutionalized adults ≥ 65 years old [8]. This decline in functional ability negatively impacts the health and quality of life of older adults, and ultimately leads to a higher mortality rate and a heavy societal burden [9–11]. Therefore, it is of great importance to society and its members to identify factors which can predict this decline in functional ability, and to delay or prevent its occurrence altogether.

Table 1 shows the baseline characteristics of the study participants. The average age of the study population was 73 years old, and participants had an average of 2 comorbidities. The average ADL score at baseline was 0.93. The average BMI, MAC and CC were 23.17 kg/m2, 27.96 cm, and 33.35 cm, respectively. When ADLs were reassessed at 4 and 8 years after baseline, the proportion of adults who experienced functional decline was 13.70% and 20.76%, respectively.

This study demonstrated that BMI, MAC and CC correlate with current and subsequent ADL scores. Moreover, the correlations between these variables and functional ability and decline at 4 and 8 years are independent of each other.

This study demonstrated that BMI, MAC, and CC are all associated with current functional ability for elderly adults ≥ 65 years of age. A high BMI significantly increases the risk of subsequent ADL decline over 4 and 8 years. Compared to BMI and MAC, a high CC is a significant predictor of current functional ability in adults ≥ 65 years old. Finally, MAC was not related with either subsequent functional ability or decline of functional ability in this study population. The results of this study suggest that BMI can be used as a long-term predictor of functional decline in elderly Taiwanese adults ≥ 65 years old, while CC is a good indicator of current functional ability.

 

Source:

http://doi.org/10.1371/journal.pone.0175062

 

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