Phase Angle Is an Independent and Additive Risk Factor of Falling in Older Adults As an Integrative Bioelectrical Marker of Muscle Function and Mass

Presentation Number: MON 357
Date of Presentation: April 3rd, 2017

Namki Hong*1, Da Hea Seo1, Sungjae Shin2, Chang Oh Kim3, Yoosik Youm4, Hyeon Chang Kim5 and Yumie Rhee1
1Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 2Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, 3Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 4Yonsei University, Seoul, Korea, Republic of (South), 5Yonsei University College of Medicine

Abstract

Falls are the leading cause of fatal injuries including major osteoporotic fractures among older adults (1). Although sarcopenia has been proposed as an important risk factor, there is currently no consensus on definitions or assessments. Thus, more comprehensive clinical indicators are needed to assess the risk of falls in elderly. Bioimpedance analysis (BIA)-derived phase angle (PhA, °), reflecting relatively lesser amount and poor quality of soft tissue mass in low PhA, was found to be associated with nutritional status, disease severity, and mortality in chronic diseases (2). However, whether PhA is associated with the risk of falling in older adults has not been investigated yet. Data of 1846 community-dwelling older adults those who underwent BIA (InBody720, BioSpace, Seoul, Korea) were retrieved from Korean Ulban Rural Elderly cohort dataset. Falls in the past year was assessed using interviewer-assisted questionnaire as primary outcome. PhA was calculated using BIA-derived resistance (R) and reactance (Xc) measured at 50 kHz as arctangent(Xc/R) x (180/ π) (3). Physical performance was measured as maximum power (W/kg) in single two leg jump. After excluding those with history of malignancy, estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73m2, leukocytosis or leukocytopenia, or those without jump power measurements, a total of 1272 subjects were analyzed in this study. Mean age of study subjects was 71.4 ± 4.3 years and 808 (63.5%) were women. Falls in the past year was detected in 272 subjects (21.4%). Prevalence of falls was increased in stepwise fashion from highest PhA tertile (≥ 5.04°, 14.8%) to lowest tertile (< 4.57°, 26.9%; P for trend < 0.001). PhA was strongly correlated with age (r = -0.23), jump power (r = 0.54), appendicular skeletal muscle mass measured by BIA (ASM, r = 0.48), and albumin (r = -0.16, P < 0.001 in all). In multivariable logistic regression analysis, 1° decrease of PhA was associated with 58% increased odds of falling (odds ratio 1.58, 95% CI 1.14-2.17, P = 0.005), independent of age, sex, body mass index, regular exercise, smoking status, alcohol intake, comorbidities, cognitive decline, anemia, nutritional status, and kidney function. The association between PhA and risk of falls was largely mediated by muscle function and mass (odds ratio 1.39, 95% CI 0.99-1.95, P = 0.052) when jump power and ASM entered into the model. PhA significantly improved the discrimination of falls when added to multivariable model including conventional risk factors (category-free net reclassification improvement [NRI] 0.172, P = 0.012), whereas jump power (NRI 0.124, P = 0.069) or ASM (NRI 0.011, P = 0.866) did not. Our findings suggest that low PhA, an integrative non-invasive bioelectrical marker of poor muscle function, mass, and nutrition, may be an independent and additive risk factor for prevalent falls in older adults, which merits further investigation.

 

Nothing to Disclose: NH, DHS, SS, COK, YY, HCK, YR