JAMDA 15 (2014) 150.e11e150.e16
JAMDA journal homepage: www.jamda.com
Original Study
Disability Associated With Obesity, Dynapenia and Dynapenic-Obesity in Chinese Older Adults Ming Yang MD, Xiang Ding MS, Li Luo MD, Qiukui Hao MD, Birong Dong MD * The Center of Gerontology and Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
a b s t r a c t Keywords: Disability obesity dynapenia dynapenic-obesity
Objectives: Whether the combination of obesity and low muscle strength (dynapenic-obesity) would cause greater impairment of the activities of daily living (ADL)/instrumental activities of daily living (IADL) than obesity alone and low muscle strength alone (dynapenia) remains unclear. The aim of this study was to reveal the possible independent and additive effects of dynapenia and obesity on ADL/IADL disability in an older Chinese population. Methods: A cross-sectional study, including 616 community-dwelling older adults, was conducted in China from 2010 to 2012. Based on the World Health Organization Asian Criteria of Obesity and handgrip strength tertiles, 4 independent groups were identified as follows: nondynapenia/nonobesity, dynapenia alone, obesity alone, and dynapenic-obesity. The Katz Index of Independence in ADL was used to assess ADL disability, whereas 6 IADL items of the Older Americans Resources and Services (OARS) multidimensional functional assessment questionnaire were used to assess IADL disability. Results: The prevalence of ADL and IADL disability was 21.1% and 28.9% in the dynapenic-obesity group, 15.5% and 22.6% in the dynapenia alone group, 13.1% and 19.6% in the obesity alone group, and 11.9% and 12.9% in the nondynapenia/nonobesity group, respectively. After adjusting for the covariates, in comparison with the dynapenic-obesity group, the adjusted odds ratios (95% confidence interval) for ADL disability were 0.36 (0.13e0.73) in the nondynapenia/nonobesity group, 0.51 (0.20e0.78) in the dynapenia-alone group, and 0.40 (0.11e0.61) in the obesity-alone group. The corresponding data for IADL disability were 0.55 (0.20e0.93), 0.82 (0.39e0.98), and 0.61 (0.30e0.91), respectively. Conclusion: Dynapenia, obesity, and dynapenic-obesity were associated with an increased risk of ADL/ IADL disability. Dynapenic-obesity was associated with a greater risk of ADL/IADL disability in comparison with dynapenia or obesity alone. Ó 2014 - American Medical Directors Association, Inc. All rights reserved.
The prevalence of obesity, a worldwide health problem, is increasing in all age groups, including the older population.1 The association between obesity and disability in older adults has been shown in a growing number of cross-sectional2,3 and longitudinal studies.4,5 Regardless of the method of measuring disability, these studies conclude that obesity is related to disability. In addition to obesity, another important aspect of age-related change in body composition is age-related loss of muscle mass, which was termed sarcopenia by Rosenberg in 1989.6 People rely on This study was funded by the National Department Public Benefit Research Foundation by the Ministry of Health P. R. China (No. 201002011). The sponsor has no role in the design, methods, data collection, analysis and preparation of the paper. Drs. Yang and Ding contributed equally to this work. The authors declare no conflicts of interest. * Address correspondence to Birong Dong, MD, Department of Geriatrics, West China Hospital of Sichuan University, 37 Guoxue Lane, Chengdu, China. E-mail address: [email protected] (B. Dong).
skeletal muscles for every movement and activity of daily life (ADL), and sarcopenia is understandably associated with functional limitation and disability. There is evidence7 to support this view, but other studies8e10 do not support the association between sarcopenia and disability. Muscle mass and muscle strength decrease with advancing age, and muscle strength is not solely dependent on muscle mass.11 The age-related changes in muscle mass can explain less than 5% of the variance in muscle strength.12 Recently, Manini and Clark13 summarized the results of 16 studies that addressed the relationship between muscle mass or muscle strength and disability or mortality, and found that age-related loss of muscle strength is a more consistent risk for disability and mortality than loss of muscle mass. They coined the term “dynapenia” to describe age-related loss of muscle strength.13,14 Based on the concept of dynapenia, another new concept, dynapenic-obesity, emerged, and it refers to the combination of obesity and dynapenia. Obesity and dynapenia are associated with
1525-8610/$ - see front matter Ó 2014 - American Medical Directors Association, Inc. All rights reserved. http://dx.doi.org/10.1016/j.jamda.2013.10.009
M. Yang et al. / JAMDA 15 (2014) 150.e11e150.e16
disability in older adults, and it would be rational to hypothesize that older adults with dynapenic-obesity would have greater functional impairments than those with obesity or dynapenia alone. There are limited data addressing this hypothesis, but in a longitudinal study, Stenholm and colleagues15 found that older people with obesity in the lowest leg strength tertile had a greater decline in mobility than the other participants. To the best of our knowledge, no study has addressed the effect of obesity, dynapenia, and dynapenic-obesity on disability in ADLs and instrumental ADLs (IADLs) in Chinese older adults. We conducted this study to reveal the potential effects of dynapenia and obesity on ADL/IADL disability in an older Chinese population. Methods Study Population The participants were from the Comprehensive Geriatric Assessment and Health Care Service System in Chinese Elderly Project. This cross-sectional study was conducted in 2 cities (Chengdu and Suining) in Sichuan province in China. From Oct 2010 to Aug 2012, 887 community-dwelling persons from Chengdu or Suining, aged 60 years and older, were included in this survey. This study protocol was approved by the Research Ethics Committee of Sichuan University and informed consent was obtained from all the participants (or their legal proxies). All interviewers were trained by using investigation manuals, multimedia materials, and simulated patients. Each interviewer needed to pass the test before the formal investigation. Trained personnel visited and evaluated all the study participants at their homes or community centers for data collection. The anthropometric measurements were performed by trained personnel, and biological specimens were collected. Anthropometric Measures Body height and weight were measured using a wall-mounted stadiometer and a digital floor scale to the nearest 0.1 cm and 0.1 kg respectively. The body mass index (BMI: body weight [kg]/ height2 [m2]) was calculated. Using a steel measuring tape (Reynolds; Baofeng Inc, Ningbo, China), the waist circumference (WC) was measured to the nearest 0.1 cm; the measurement was taken on bare skin following a light expiration, with the participant standing. Measurement of Hand Grip Strength Handgrip strength (in kg) was measured by a handheld dynamometer based on strain gauge sensors (EH101; Xiangshan Inc, Guangdong, China). Both hands were tested with the participant seated, elbow flexed at a 110 angle, with the wrist in a neutral position, and the interphalangeal joint of the index finger at a 90 angle. Two readings were taken, and the highest value was used for the analysis. We conducted a preliminary study to evaluate the reliability of the handgrip strength test using the intraclass correlation coefficient (ICC). The result indicated that the test-retest reliability of the handgrip strength test was excellent (ICC ¼ 0.85, n ¼ 115). Classification of Obesity, Dynapenia, and Dynapenic-Obesity According to the World Health Organization Asian Criteria of Obesity,16 the participants represented either the nonobesity group (
JAMDA journal homepage: www.jamda.com
Original Study
Disability Associated With Obesity, Dynapenia and Dynapenic-Obesity in Chinese Older Adults Ming Yang MD, Xiang Ding MS, Li Luo MD, Qiukui Hao MD, Birong Dong MD * The Center of Gerontology and Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
a b s t r a c t Keywords: Disability obesity dynapenia dynapenic-obesity
Objectives: Whether the combination of obesity and low muscle strength (dynapenic-obesity) would cause greater impairment of the activities of daily living (ADL)/instrumental activities of daily living (IADL) than obesity alone and low muscle strength alone (dynapenia) remains unclear. The aim of this study was to reveal the possible independent and additive effects of dynapenia and obesity on ADL/IADL disability in an older Chinese population. Methods: A cross-sectional study, including 616 community-dwelling older adults, was conducted in China from 2010 to 2012. Based on the World Health Organization Asian Criteria of Obesity and handgrip strength tertiles, 4 independent groups were identified as follows: nondynapenia/nonobesity, dynapenia alone, obesity alone, and dynapenic-obesity. The Katz Index of Independence in ADL was used to assess ADL disability, whereas 6 IADL items of the Older Americans Resources and Services (OARS) multidimensional functional assessment questionnaire were used to assess IADL disability. Results: The prevalence of ADL and IADL disability was 21.1% and 28.9% in the dynapenic-obesity group, 15.5% and 22.6% in the dynapenia alone group, 13.1% and 19.6% in the obesity alone group, and 11.9% and 12.9% in the nondynapenia/nonobesity group, respectively. After adjusting for the covariates, in comparison with the dynapenic-obesity group, the adjusted odds ratios (95% confidence interval) for ADL disability were 0.36 (0.13e0.73) in the nondynapenia/nonobesity group, 0.51 (0.20e0.78) in the dynapenia-alone group, and 0.40 (0.11e0.61) in the obesity-alone group. The corresponding data for IADL disability were 0.55 (0.20e0.93), 0.82 (0.39e0.98), and 0.61 (0.30e0.91), respectively. Conclusion: Dynapenia, obesity, and dynapenic-obesity were associated with an increased risk of ADL/ IADL disability. Dynapenic-obesity was associated with a greater risk of ADL/IADL disability in comparison with dynapenia or obesity alone. Ó 2014 - American Medical Directors Association, Inc. All rights reserved.
The prevalence of obesity, a worldwide health problem, is increasing in all age groups, including the older population.1 The association between obesity and disability in older adults has been shown in a growing number of cross-sectional2,3 and longitudinal studies.4,5 Regardless of the method of measuring disability, these studies conclude that obesity is related to disability. In addition to obesity, another important aspect of age-related change in body composition is age-related loss of muscle mass, which was termed sarcopenia by Rosenberg in 1989.6 People rely on This study was funded by the National Department Public Benefit Research Foundation by the Ministry of Health P. R. China (No. 201002011). The sponsor has no role in the design, methods, data collection, analysis and preparation of the paper. Drs. Yang and Ding contributed equally to this work. The authors declare no conflicts of interest. * Address correspondence to Birong Dong, MD, Department of Geriatrics, West China Hospital of Sichuan University, 37 Guoxue Lane, Chengdu, China. E-mail address: [email protected] (B. Dong).
skeletal muscles for every movement and activity of daily life (ADL), and sarcopenia is understandably associated with functional limitation and disability. There is evidence7 to support this view, but other studies8e10 do not support the association between sarcopenia and disability. Muscle mass and muscle strength decrease with advancing age, and muscle strength is not solely dependent on muscle mass.11 The age-related changes in muscle mass can explain less than 5% of the variance in muscle strength.12 Recently, Manini and Clark13 summarized the results of 16 studies that addressed the relationship between muscle mass or muscle strength and disability or mortality, and found that age-related loss of muscle strength is a more consistent risk for disability and mortality than loss of muscle mass. They coined the term “dynapenia” to describe age-related loss of muscle strength.13,14 Based on the concept of dynapenia, another new concept, dynapenic-obesity, emerged, and it refers to the combination of obesity and dynapenia. Obesity and dynapenia are associated with
1525-8610/$ - see front matter Ó 2014 - American Medical Directors Association, Inc. All rights reserved. http://dx.doi.org/10.1016/j.jamda.2013.10.009
M. Yang et al. / JAMDA 15 (2014) 150.e11e150.e16
disability in older adults, and it would be rational to hypothesize that older adults with dynapenic-obesity would have greater functional impairments than those with obesity or dynapenia alone. There are limited data addressing this hypothesis, but in a longitudinal study, Stenholm and colleagues15 found that older people with obesity in the lowest leg strength tertile had a greater decline in mobility than the other participants. To the best of our knowledge, no study has addressed the effect of obesity, dynapenia, and dynapenic-obesity on disability in ADLs and instrumental ADLs (IADLs) in Chinese older adults. We conducted this study to reveal the potential effects of dynapenia and obesity on ADL/IADL disability in an older Chinese population. Methods Study Population The participants were from the Comprehensive Geriatric Assessment and Health Care Service System in Chinese Elderly Project. This cross-sectional study was conducted in 2 cities (Chengdu and Suining) in Sichuan province in China. From Oct 2010 to Aug 2012, 887 community-dwelling persons from Chengdu or Suining, aged 60 years and older, were included in this survey. This study protocol was approved by the Research Ethics Committee of Sichuan University and informed consent was obtained from all the participants (or their legal proxies). All interviewers were trained by using investigation manuals, multimedia materials, and simulated patients. Each interviewer needed to pass the test before the formal investigation. Trained personnel visited and evaluated all the study participants at their homes or community centers for data collection. The anthropometric measurements were performed by trained personnel, and biological specimens were collected. Anthropometric Measures Body height and weight were measured using a wall-mounted stadiometer and a digital floor scale to the nearest 0.1 cm and 0.1 kg respectively. The body mass index (BMI: body weight [kg]/ height2 [m2]) was calculated. Using a steel measuring tape (Reynolds; Baofeng Inc, Ningbo, China), the waist circumference (WC) was measured to the nearest 0.1 cm; the measurement was taken on bare skin following a light expiration, with the participant standing. Measurement of Hand Grip Strength Handgrip strength (in kg) was measured by a handheld dynamometer based on strain gauge sensors (EH101; Xiangshan Inc, Guangdong, China). Both hands were tested with the participant seated, elbow flexed at a 110 angle, with the wrist in a neutral position, and the interphalangeal joint of the index finger at a 90 angle. Two readings were taken, and the highest value was used for the analysis. We conducted a preliminary study to evaluate the reliability of the handgrip strength test using the intraclass correlation coefficient (ICC). The result indicated that the test-retest reliability of the handgrip strength test was excellent (ICC ¼ 0.85, n ¼ 115). Classification of Obesity, Dynapenia, and Dynapenic-Obesity According to the World Health Organization Asian Criteria of Obesity,16 the participants represented either the nonobesity group (
