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Sarcopenia influences fall-related injuries in community-dwelling older adults
Geriatric Nursing xx (2014) 1e4
Contents lists available at ScienceDirect
Geriatric Nursing journal homepage: www.gnjournal.com
Feature Article
Sarcopenia influences fall-related injuries in community-dwelling older adults Namhyun Woo, BSN, RN, Su Hyun Kim, PhD, RN * College of Nursing, Kyungpook National University, South Korea
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 November 2013 Received in revised form 25 February 2014 Accepted 3 March 2014 Available online xxx
This study aimed to determine the relationship between sarcopenia and fall-related injuries in community-dwelling older adults in Korea. The study population comprised 2848 subjects aged 65 years or older who participated in the Korea National Health and Nutrition Examination Surveys during 2010 e2011. Sarcopenia was considered to be present if the subject’s appendicular skeletal muscle mass divided by his or her weight was less than 29.9% in men, or less than 25.1% in women. The incidence of fall-related injuries during the past year among all the respondents was 4.3%, and the prevalence of sarcopenia was 32.2%. After controlling for sociodemographic variables and morbidity due to chronic diseases, the incidence of fall-related injuries remained significantly elevated among older adults with sarcopenia (odds ratio ¼ 1.61, 95% confidence internal ¼ 1.01e2.54). Sarcopenia should be considered when investigating means of preventing of fall-related injuries in community-dwelling older adults. To prevent falls among these persons, it is vital to implement intervention programs that increase muscle mass. Ó 2014 Mosby, Inc. All rights reserved.
Keywords: Accidental falls Elderly Sarcopenia
Introduction Among older adults, falls are one of the most common accidents that can cause disability or impairment.1,2 Approximately 28%e35% of older adults are reported to fall each year, worldwide.3 Further, it has been reported that 21%e48% of older adults in Korea experience falls each year.4,5 Of these individuals who experienced falls, 80% developed an injury and 63% received treatment at a hospital.5 In the United States, falls are the second largest contributor to the economic burden of injuries (in terms of lifetime costs).2 Similarly, health care expenditure associated with fall-related injuries is expected to rise in Korea, accompanying rapid increases in the size of the elderly population. Accidental falls among community-dwelling older adults have been shown to contribute to hospital visits, nursing home placements, and functional decline.6,7 Therefore, it is critical to identify risk factors for accidental falls in the community.8e10 In a systematic review, muscle strength, gait, and balance impairments were found to be the strongest risk factors for falls among communitydwelling older adults.1 In particular, lower or upper extremity muscle weakness significantly increased the odds ratio (OR) for
injurious falls.11 However, limited information is available regarding the independent effect of loss of skeletal muscle mass with aging and its association with muscle strength and falls.12 The loss of skeletal muscle mass that occurs with aging is known as sarcopenia. Previous investigations have shown that sarcopenia is closely associated with declining muscle quality13 and muscle strength in the older population.14 Sarcopenia is considered to play a crucial role in the frailty process, leading to poor outcomes, including falls, multiple trauma, functional decline, disability, poor quality of life, nursing home placement, and mortality.12 Nonetheless, findings regarding the relationship between sarcopenia and falls have been inconsistent.15e17 Thus, it is essential to clarify the independent relationship between sarcopenia and falls. Indeed, doing so may lay the groundwork for interventions that successfully prevent falls among community-dwelling older adults. Therefore, the aim of the current study was to assess the influence of sarcopenia on fall-related injuries in communitydwelling older adults in Korea. To increase the validity of our findings, we used the Korea National Health and Nutrition Examination Survey (KNHANES), which is nationally representative. Methods
This research was supported by Kyungpook National University Research Fund, 2011. * Corresponding author. College of Nursing, Daegu, Kyungpook National University, Korea 700-422. Tel.: þ82 53 420 4928. E-mail address: [email protected] (S.H. Kim). 0197-4572/$ e see front matter Ó 2014 Mosby, Inc. All rights reserved. http://dx.doi.org/10.1016/j.gerinurse.2014.03.001
Study population and data collection Data on subjects were obtained from KNHANES V-1 and V-2. KNHANES is a nationwide survey on health and nutrition status,
2
N. Woo, S.H. Kim / Geriatric Nursing xx (2014) 1e4
conducted by the Korea Centers for Disease Control and Prevention. It provides baseline data for developing health promotion programs and health-related policies. Study subjects in the KNHANES were randomly sampled according to stratified regions, gender, age composition, and average size and price of housing. Data were collected throughout the year 2010 for KNHANES V-1 and 2011 for KNHANES V-2. In total, the survey was completed by 81.9% of the interviewed subjects in KNHANES V-1 and 80.4% of those in KNHANES V-2. Of the 17,476 subjects in both surveys, 3076 who were 65 years or older were selected for the current study. After excluding 228 subjects who did not respond to the questionnaire on falls, a total of 2848 participants were included for analysis in this study. Assessment of fall-related injuries and sarcopenia We defined fall-related injuries as unintentional injuries due to falls or sliding accidents during the past year. Fall-related injuries were assessed using the following questions. First, participants were asked, “Have you ever experienced accidents that required treatment at a hospital or emergency room?” Respondents who answered, “Yes,” were additionally asked, “How did the accident occur?” Older adults were considered to have experience with fallrelated injuries if they reported accidental falls from high locations or had accidentally slipped onto the ground and been treated by health care providers.18 To measure sarcopenia, we adopted a formula in which the appendicular skeletal muscle mass (ASM) is divided by total weight.19,20 Appendicular muscle mass was measured using dualenergy X-ray absorptiometry (Discovery-W; Hologic Inc., Waltham, MA, USA) by determining differences in the transmittance of each subject’s body composition. As a component of KNHANES, a dual-energy X-ray absorptiometry was performed on all study subjects at a mobile examination center. According to a previous study in an older Korean population, members of the sarcopenic group were more likely to have cardiometabolic risk factors than were members of the normal community-based elderly cohort.21 In that study, the sarcopenic group included subjects who met the defined criteria for sarcopenia (ASM/weight, <29.9% in men and <25.1% in women).
variables and disease morbidity. In the multiple logistic regression analyses, education and income were treated as continuous variables. Multicollinearity was ruled out using Spearman’s rho for correlation analyses, the results of which demonstrated low correlations between predictors (rho < 0.45 for all variables).23 Additionally, the absence of multicollinearity was supported by multiple linear and logistic regression analyses, in which the low percentage of variance for each predictor was accounted for by the other predictors (R2 or pseudo-R2 < 0.12 for all predictors). An alpha level of 0.05 was selected for assessments of statistical significance. Data were analyzed using SPSS 19.0 (SPSS, Inc., Chicago, IL, USA) complex samples procedures. Results Table 1 shows the characteristics of the participants according to history of fall-related injuries. Of the 2848 participants, 120 (4.3%) had experienced one or more fall-related injuries in the past year. The mean (standard deviation) age was 73.17 (0.14) years, and 58.8% of the participants were women. In univariate analyses, the incidence of fall-related injuries differed significantly according to gender. Women accounted for 71.2% of the respondents who had experienced fall-related injuries, and men accounted for 28.8% (c2 ¼ 7.97, p ¼ 0.022). The incidence of falls however did not differ according to age, education, income, living arrangement, or body mass index. Older adults who had experienced fall-related injuries had higher rates of morbidity in terms of stroke (7.9% vs. 3.4%, c2 ¼ 7.04, p ¼ 0.013) and depression (4.7% vs. 2.1%, c2 ¼ 3.82, p ¼ 0.049). However, no significant differences were observed for arthritis or diabetes mellitus. Of the total respondents, 1404 (49.3%) had sarcopenia. Subjects with sarcopenia were significantly more likely to have experienced fall-related injuries (63.3% vs. 48.7%, c2 ¼ 5.96, p ¼ 0.008). Table 1 Characteristics of participants (N ¼ 2848). Variables
Total (n ¼ 2848)
Fallers (n ¼ 120)
Non fallers (n ¼ 2728)
c2/t
p
n (%)
Data analysis Descriptive statistics were used to analyze subjects’ sociodemographic characteristics. In light of the inherent statistical complications involved in multistage, complex survey designs, the investigators followed the guidelines of KNHANES for the analysis of sample weights. By using these weights appropriately, the stratification and clustering of the design were incorporated into the analyses to ensure appropriate estimates and standard errors.22 t-tests and chi-square tests were employed to test differences between subjects who had and had not experienced fall-related injuries. To assess whether sarcopenia had an independent influence on fall-related injury (above and beyond the influences of potential confounders), we applied a hierarchical multiple logistic regression analysis. The regression analysis was used to estimate the relationship between sarcopenia and the risk of fall-related injuries after adjusting for covariates.23 In model 1, we included demographic variables that may be associated with falls or sarcopenia3,4,24: age, gender, educational difference, income, and marital status. In model 2, we additionally incorporated covariates related to disease morbidity: stroke, arthritis, diabetes, and depression.1,25 Finally, model 3 included each covariate in model 2, as well as sarcopenia status, which was thereby adjusted for demographic
Age, year (mean (SE)) 73.17 (0.14) 73.41 Gender Women 1675 (58.8) 85 Men 1173 (41.2) 35 Education Less than elementary 2047 (71.9) 89 school graduate 313 (11.0) 14 Middle school graduate High school graduate 327 (11.5) 14 More than a college 159 (5.6) 3 graduate Income quartile Low 772 (27.1) 37 Middle-low 722 (25.3) 27 Middle-high 702 (24.7) 28 High 652 (22.9) 28 Living arrangement Living alone 478 (16.8) 25 Living with others 2370 (83.2) 95 Morbidity of disease Stroke 103 (3.6) 9 Arthritis 803 (28.2) 41 Diabetes 501 (17.6) 24 Depression 63 (2.2) 6 Sarcopenia 1404 (49.3) 76 Body mass index 23.72 (0.10) 24.08 (mean (SE))
(0.49) 72.93 (0.13) 0.97 0.335 (71.2) (28.8)
1590 (58.3) 7.97 0.022 1138 (41.7)
(73.9)
1958 (71.8)
(11.7)
301 (11.0) 2.05 0.574
(11.6) (2.7)
313 (11.5) 156 (5.8)
(31.2) (22.3) (23.1) (23.4)
735 695 674 624
(21.0) (79.0)
(27.0) (25.5) 1.33 0.764 (24.7) (22.9)
453 (16.6) 1.66 0.287 2275 (83.4)
(7.9) 94 (33.8) 762 (19.9) 477 (4.7) 57 (63.3) 1328 (0.33) 23.71
(3.4) (28.0) (17.5) (2.1) (48.7) (0.10)
7.04 1.95 0.46 3.82 5.97 1.16
0.013 0.307 0.499 0.049 0.008 0.237
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We used hierarchical multiple logistic regression analysis to estimate the effect of sarcopenia on the risk of fall-related injuries, after adjusting for sociodemographic variables and chronic diseases (Table 2). According to model 1, the OR for fall-related injuries was significantly higher for women than for men (OR ¼ 1.78, 95% confidence interval [CI] ¼ 1.05e3.03). In model 2, morbidity in terms of stroke significantly increased the OR for fall-related injuries (OR ¼ 2.62, 95% CI ¼ 1.24e5.55); however, arthritis, diabetes mellitus, and depression were not significant predictors. Female gender was not a significant predictor of fall-related injuries in model 2 (OR ¼ 1.77, 95% CI ¼ 0.99e3.16). Finally, in model 3, which controlled for sociodemographic variables and disease morbidity, sarcopenia was the significant predictor affecting fall-related injuries. Among this older population, the risk of fall-related injuries was higher for individuals with sarcopenia than for those without sarcopenia (OR ¼ 1.59, 95% CI ¼ 1.02e2.49). Morbidity in terms of stroke also significantly increased the OR for fall-related injuries (OR ¼ 2.63, 95% CI ¼ 1.05e6.59). Discussion In the current study, we evaluated the influence of sarcopenia on fall-related injuries in older community-dwelling Korean adults. Our findings demonstrated a high prevalence of sarcopenia among older Korean adults, accounting for 49.3% of the population. Older Korean adults with sarcopenia had a higher rate of fall-related injuries than did their counterparts without sarcopenia. Consistent with the results of a previous study among elderly Italians, sarcopenia was shown to have a strong effect on fall-related injuries, after adjusting for other sociodemographic variables and disease morbidity.16 In the current study, the incidence of fall-related injuries was 4.3%, which was similar to the 4.9% incidence that was reported in a recent study conducted in the United States.26 However, the incidence was far lower than that reported by a previous study, which found that 15.2% of older Korean adults had received medical attention and 28.9% had been hospitalized as a result of falls.4,5 The discrepancy between these fall-related injury rates may be attributable to differences in the quantification of falls, such as the assessment of fall-related injuries treated by health care providers rather than the incidence of falls. Additionally, the discrepancy may have resulted from the current study’s use of representative community samples.5,27
Table 2 Hierarchical multiple logistic regression analysis on influence of sarcopenia on fall injuries (N ¼ 2848). Model 1
Model 2
Model 3
1.02 (0.98e1.05) 1.77 (0.99e3.16)
1.01 (0.97e1.05) 1.28 (0.67e2.45)
1.08 (0.84e1.39) 0.99 (0.77e1.23) 1.21 (0.65e2.23)
1.10 (0.82e1.49) 0.97 (0.73e1.29) 1.11 (0.48e2.56)
2.62 0.99 1.13 0.49
2.63 0.94 0.85 0.41 1.59
OR (95% CI) Sociodemographic Age 1.02 (0.98e1.05) Gender (female 1.78 (1.05e3.03)* vs. male) Education 1.08 (0.84e1.39) Income 0.98 (0.77e1.25) Living arrangement 1.16 (0.62e2.19) (living alone vs. living with others) Morbidity of chronic diseases Stroke Arthritis Diabetes Depression Sarcopenia *p < 0.05.
(1.24e5.55)* (0.59e1.68) (0.71e1.79) (0.20e1.21)
(1.05e6.59)* (0.50e1.76) (0.46e1.58) (0.07e2.57) (1.02e2.49)*
3
Using the indicator of ASM/weight, which reflects the relative quantity of muscle mass as a component of the total body composition,19 the high prevalence of sarcopenia (49.3%) in the current study was comparable to the results of previous studies in Korea and the United States. These previous studies reported prevalence rates of 38% and 52% in men and 63% and 69% in women, respectively.21,28 However, the prevalence of sarcopenia in our study was much higher than that reported in studies measuring sarcopenia using the ASM/height2 indicator, which reflects the absolute quantity of muscle mass, disregarding body composition.15 The latter study concluded that only 6.3% and 4.1% of older Korean men and women, respectively, had sarcopenia.29 The relationship between sarcopenia and fall-related injuries in the current study may be explained by the critical role of sarcopenia in the frailty process. Frailty plays a role in the poor outcomes of falls, such as various traumas, functional decline, and disability.12,13,28,30 Early seminal studies on sarcopenia reported that reduced muscle mass may result in low physical performance, a decline in mobility, and functional impairment,31e34 which can be regarded as distinctive characteristics of frailty. Therefore, we believe that fall-related accidents may occur as results of decreased agility, decreased flexibility, and delayed reactions, which themselves result from sarcopenia. Accordingly, the current study provides evidence of the need for fall prevention interventions that reduce risk factors for sarcopenia. In particular, there is a need for interventions promoting physical activities that increase muscle mass among older adults. Regarding the successful prevention of fall-related injuries in the community, the current study’s findings underscore the importance of identifying older adults with sarcopenia and implementing targeted approaches in this subgroup. The significant relationship between sarcopenia and fall-related injuries provides suggestions for elements that should be included in multi-factorial interventions, including physical activity and adequate nutrition programs.16,35 There are various means of slowing the decline in muscle mass that is associated with aging. Specifically, it may be valuable to increase health care providers’ awareness of sarcopenia in older adults. Further, it may be worthwhile to implement structured exercise programs (including progressive resistance or power training) and nutritional interventions (including sufficient protein and additional caloric intake).36 The current study had some limitations. First, it is possible that the findings would have differed if we had used a different method to quantify sarcopenia. In the current study, we quantified sarcopenia using the ASM/weight indicator, which overcomes important limitations of the ASM/height2 indicator. Indeed, the ASM/height2 indicator insufficiently accommodates reduced mobility in older adults37 and does not provide an appropriate definition of sarcopenia in Asians.21 Second, we employed secondary data analysis, which might have made the measurement of some key variables difficult, possibly influencing the results. When assessing falls, we measured fall-related injury rather than fall accidents because we could only obtain information on fallrelated injuries from the existing KNHANES data. Despite these limitations, our study has the advantage of using a representative sample of the Korean population. Our results suggest that sarcopenia is a critical problem among the elderly and must be considered by health care providers in preventing fall-related injuries in the community. In conclusion, sarcopenia is an important factor that contributes to the increased risk of fall-related injuries among communitydwelling elderly adults in Korea. Therefore, physical activity programs, nutritional programs, and other such interventions should be considered first for the prevention of fall-related injury.38e40 Further, interventions such as physical activity and nutritional
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programs should be incorporated into fall-prevention programs in the community setting. References 1. Tinetti ME, Kumar C. The patient who falls: “It’s always a trade-off”. J Am Med Assoc. 2010;303:258e266. 2. Heinrich S, Rapp K, Rissmann U, Becker C, Konig HH. Cost of falls in old age: a systematic review. Osteoporos Int. 2010;21:891e902. 3. WHO Global Report on Falls Prevention in Older Age. Canadna: World Health Organization; 2007. 4. Jung KH, Oh YH, Lee YK, et al. 2011 Survey of the Elderly. Korea: Ministry of Health & Welfare; 2012 Apr:901p. Report No.: 11-1352000-000672-12. 5. Yoo Y. Falls and functional levels associated with falls in older people living in the community. J Korean Gerontol Nurs. 2010;12:40e50. 6. Centers for Disease Control and Prevention. National Center for Health Statistics. Injury mortality: US/State, 1999e2010 (Source: NVSS). Available at: www. cdc.gov/nchs/hdi.htm; Accessed 03.09.13. 7. Centers for Disease Control and Prevention. National Center for Health Statistics. Injury visits to emergency departments by intent and mechanism: US/ State, 2002e2010 (Source: NVSS). Available at: www.cdc.gov/nchs/hdi.htm; Accessed 03.09.13. 8. Gallagher B, Corbett E, Freeman L, et al. A fall prevention program for the home environment. Home Care Provid. 2001;6:157e163. 9. Johnson M, Cusick A, Chang S. Home-screen: a short scale to measure fall risk in the home. Public Health Nurs. 2001;18:169e177. 10. Choo J, Kim E. Health-related quality of life of fallers vs. non-fallers in community-dwelling elderly people. J Muscle Jt Health. 2012;19:373e382. 11. Moreland JD, Richardson JA, Goldsmith CH, Clase CM. Muscle weakness and falls in older adults: a systematic review and meta-analysis. J Am Geriatr Soc. 2004;52:1121e1129. 12. Cruz-Jentoft AJ, Landi F, Topinkova E, Michel JP. Understanding sarcopenia as a geriatric syndrome. Curr Opin Clin Nutr Metab Care. 2010;13:1e7. 13. Schwartz RS. Sarcopenia and physical performance in old age: introduction. Muscle Nerve Suppl. 1997;5:S10eS12. 14. Morley JE, Baumgartner RN, Roubenoff R, Mayer J, Nair KS. Sarcopenia. J Lab Clin Med. 2001;137:231e243. 15. Baumgartner RN, Koehler KM, Gallagher D, et al. Epidemiology of sarcopenia among the elderly in New Mexico. Am J Epidemiol. 1998;147:755e763. 16. Landi F, Liperoti R, Russo A, et al. Sarcopenia as a risk factor for falls in elderly individuals: results from the ilSIRENTE study. Clin Nutr. 2012;31:652e658. 17. Rolland Y, Lauwers-Cances V, Cournot M, et al. Sarcopenia, calf circumference, and physical function of elderly women: a cross-sectional study. J Am Geriatr Soc. 2003;51:1120e1124. 18. Ministry of Health & Welfare. Korea Centers for Disease Control and Prevention. Fifth Korea National Health and Nutrition Examination Survey. Available at: http://knhanes.cdc.go.kr.do; 2010. Accessed 03.09.13. 19. Janssen I, Heymsfield SB, Wang ZM, Ross R. Skeletal muscle mass and distribution in 468 men and women aged 18e88 yr. J Appl Physiol. 2000;89:81e88. 20. Kim JH, Choi SH, Lim S, et al. Sarcopenia and obesity: gender-different relationship with functional limitation in older persons. J Korean Med Sci. 2013;28: 1041e1047.
21. Kim JH, Hwang Bo Y, Hong ES, et al. Investigation of sarcopenia and its association with cardiometabolic risk factors in elderly subjects. J Korean Geriatr Soc. 2010;14:121e130. 22. Prevention KCfDCa. Guideline for the Analysis of the Korea National Health and Nutrition Examination Survey. Seoul: Korea: Korea Centers for Disease Control Prevention; 2012. 23. Kellar SP, Kelvin EA. Munro’s Statistical Methods for Health Care Research. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2013. 24. Deandrea S, Lucenteforte E, Bravi F, Foschi R, La Vecchia C, Negri E. Risk factors for falls in community-dwelling older people: a systematic review and metaanalysis. Epidemiology. 2010;21:658e668. 25. Kannus P, Sievanen H, Palvanen M, et al. Prevention of falls and consequent injuries in elderly people. Lancet. 2005;366:1885e1893. 26. Stevens JA, Mack KA, Paulozzi LJ, Ballesteros MF. Self-reported falls and fallrelated injuries among persons aged>or¼65 yearseUnited States, 2006. J Safety Res. 2008;39:345e349. 27. Jung YM, Shin DS, Chung KS, Lee SE. Health status and fall-related factors among older Korean women: implications for nurses. J Gerontol Nurs. 2007;33: 12e20. 28. Janssen I, Heymsfield SB, Ross R. Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability. J Am Geriatr Soc. 2002;50:889e896. 29. Kim TN, Yang SJ, Yoo HJ, et al. Prevalence of sarcopenia and sarcopenic obesity in Korean adults: the Korean sarcopenic obesity study. Int J Obes (Lond). 2009;33:885e892. 30. Raphael D, Cava M, Brown I, et al. Frailty: a public health perspective. Can J Public Health. 1995;86:224e227. 31. Visser M, Goodpaster BH, Kritchevsky SB, et al. Muscle mass, muscle strength, and muscle fat infiltration as predictors of incident mobility limitations in well-functioning older persons. J Gerontol A Biol Sci Med Sci. 2005;60:324e333. 32. Hida T, Ishiguro N, Shimokata H, et al. High prevalence of sarcopenia and reduced leg muscle mass in Japanese patients immediately after a hip fracture. Geriatr Gerontol Int. 2013;13:413e420. 33. Iannuzzi-Sucich M, Prestwood KM, Kenny AM. Prevalence of sarcopenia and predictors of skeletal muscle mass in healthy, older men and women. J Gerontol A Biol Sci Med Sci. 2002;57:M772eM777. 34. Lauretani F, Russo CR, Bandinelli S, et al. Age-associated changes in skeletal muscles and their effect on mobility: an operational diagnosis of sarcopenia. J Appl Physiol. 2003;95:1851e1860. 35. Wang C, Bai L. Sarcopenia in the elderly: basic and clinical issues. Geriatr Gerontol Int. 2012;12:388e396. 36. von Haehling S, Morley JE, Anker SD. From muscle wasting to sarcopenia and myopenia: update 2012. J Cachexia Sarcopenia Muscle. 2012;3: 213e217. 37. Visser M. Towards a definition of sarcopeniaeresults from epidemiologic studies. J Nutr Health Aging. 2009;13:713e716. 38. Taaffe DR. Sarcopeniaeexercise as a treatment strategy. Aust Fam Physician. 2006;35:130e134. 39. Hunter GR, McCarthy JP, Bamman MM. Effects of resistance training on older adults. Sports Med. 2004;34:329e348. 40. Izquierdo M, Ibáñez J, Häkkinen K, et al. Once weekly combined resistance and cardiovascular training in healthy older men. Med Sci Sports Exerc. 2004;36: 435e443.
Contents lists available at ScienceDirect
Geriatric Nursing journal homepage: www.gnjournal.com
Feature Article
Sarcopenia influences fall-related injuries in community-dwelling older adults Namhyun Woo, BSN, RN, Su Hyun Kim, PhD, RN * College of Nursing, Kyungpook National University, South Korea
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 November 2013 Received in revised form 25 February 2014 Accepted 3 March 2014 Available online xxx
This study aimed to determine the relationship between sarcopenia and fall-related injuries in community-dwelling older adults in Korea. The study population comprised 2848 subjects aged 65 years or older who participated in the Korea National Health and Nutrition Examination Surveys during 2010 e2011. Sarcopenia was considered to be present if the subject’s appendicular skeletal muscle mass divided by his or her weight was less than 29.9% in men, or less than 25.1% in women. The incidence of fall-related injuries during the past year among all the respondents was 4.3%, and the prevalence of sarcopenia was 32.2%. After controlling for sociodemographic variables and morbidity due to chronic diseases, the incidence of fall-related injuries remained significantly elevated among older adults with sarcopenia (odds ratio ¼ 1.61, 95% confidence internal ¼ 1.01e2.54). Sarcopenia should be considered when investigating means of preventing of fall-related injuries in community-dwelling older adults. To prevent falls among these persons, it is vital to implement intervention programs that increase muscle mass. Ó 2014 Mosby, Inc. All rights reserved.
Keywords: Accidental falls Elderly Sarcopenia
Introduction Among older adults, falls are one of the most common accidents that can cause disability or impairment.1,2 Approximately 28%e35% of older adults are reported to fall each year, worldwide.3 Further, it has been reported that 21%e48% of older adults in Korea experience falls each year.4,5 Of these individuals who experienced falls, 80% developed an injury and 63% received treatment at a hospital.5 In the United States, falls are the second largest contributor to the economic burden of injuries (in terms of lifetime costs).2 Similarly, health care expenditure associated with fall-related injuries is expected to rise in Korea, accompanying rapid increases in the size of the elderly population. Accidental falls among community-dwelling older adults have been shown to contribute to hospital visits, nursing home placements, and functional decline.6,7 Therefore, it is critical to identify risk factors for accidental falls in the community.8e10 In a systematic review, muscle strength, gait, and balance impairments were found to be the strongest risk factors for falls among communitydwelling older adults.1 In particular, lower or upper extremity muscle weakness significantly increased the odds ratio (OR) for
injurious falls.11 However, limited information is available regarding the independent effect of loss of skeletal muscle mass with aging and its association with muscle strength and falls.12 The loss of skeletal muscle mass that occurs with aging is known as sarcopenia. Previous investigations have shown that sarcopenia is closely associated with declining muscle quality13 and muscle strength in the older population.14 Sarcopenia is considered to play a crucial role in the frailty process, leading to poor outcomes, including falls, multiple trauma, functional decline, disability, poor quality of life, nursing home placement, and mortality.12 Nonetheless, findings regarding the relationship between sarcopenia and falls have been inconsistent.15e17 Thus, it is essential to clarify the independent relationship between sarcopenia and falls. Indeed, doing so may lay the groundwork for interventions that successfully prevent falls among community-dwelling older adults. Therefore, the aim of the current study was to assess the influence of sarcopenia on fall-related injuries in communitydwelling older adults in Korea. To increase the validity of our findings, we used the Korea National Health and Nutrition Examination Survey (KNHANES), which is nationally representative. Methods
This research was supported by Kyungpook National University Research Fund, 2011. * Corresponding author. College of Nursing, Daegu, Kyungpook National University, Korea 700-422. Tel.: þ82 53 420 4928. E-mail address: [email protected] (S.H. Kim). 0197-4572/$ e see front matter Ó 2014 Mosby, Inc. All rights reserved. http://dx.doi.org/10.1016/j.gerinurse.2014.03.001
Study population and data collection Data on subjects were obtained from KNHANES V-1 and V-2. KNHANES is a nationwide survey on health and nutrition status,
2
N. Woo, S.H. Kim / Geriatric Nursing xx (2014) 1e4
conducted by the Korea Centers for Disease Control and Prevention. It provides baseline data for developing health promotion programs and health-related policies. Study subjects in the KNHANES were randomly sampled according to stratified regions, gender, age composition, and average size and price of housing. Data were collected throughout the year 2010 for KNHANES V-1 and 2011 for KNHANES V-2. In total, the survey was completed by 81.9% of the interviewed subjects in KNHANES V-1 and 80.4% of those in KNHANES V-2. Of the 17,476 subjects in both surveys, 3076 who were 65 years or older were selected for the current study. After excluding 228 subjects who did not respond to the questionnaire on falls, a total of 2848 participants were included for analysis in this study. Assessment of fall-related injuries and sarcopenia We defined fall-related injuries as unintentional injuries due to falls or sliding accidents during the past year. Fall-related injuries were assessed using the following questions. First, participants were asked, “Have you ever experienced accidents that required treatment at a hospital or emergency room?” Respondents who answered, “Yes,” were additionally asked, “How did the accident occur?” Older adults were considered to have experience with fallrelated injuries if they reported accidental falls from high locations or had accidentally slipped onto the ground and been treated by health care providers.18 To measure sarcopenia, we adopted a formula in which the appendicular skeletal muscle mass (ASM) is divided by total weight.19,20 Appendicular muscle mass was measured using dualenergy X-ray absorptiometry (Discovery-W; Hologic Inc., Waltham, MA, USA) by determining differences in the transmittance of each subject’s body composition. As a component of KNHANES, a dual-energy X-ray absorptiometry was performed on all study subjects at a mobile examination center. According to a previous study in an older Korean population, members of the sarcopenic group were more likely to have cardiometabolic risk factors than were members of the normal community-based elderly cohort.21 In that study, the sarcopenic group included subjects who met the defined criteria for sarcopenia (ASM/weight, <29.9% in men and <25.1% in women).
variables and disease morbidity. In the multiple logistic regression analyses, education and income were treated as continuous variables. Multicollinearity was ruled out using Spearman’s rho for correlation analyses, the results of which demonstrated low correlations between predictors (rho < 0.45 for all variables).23 Additionally, the absence of multicollinearity was supported by multiple linear and logistic regression analyses, in which the low percentage of variance for each predictor was accounted for by the other predictors (R2 or pseudo-R2 < 0.12 for all predictors). An alpha level of 0.05 was selected for assessments of statistical significance. Data were analyzed using SPSS 19.0 (SPSS, Inc., Chicago, IL, USA) complex samples procedures. Results Table 1 shows the characteristics of the participants according to history of fall-related injuries. Of the 2848 participants, 120 (4.3%) had experienced one or more fall-related injuries in the past year. The mean (standard deviation) age was 73.17 (0.14) years, and 58.8% of the participants were women. In univariate analyses, the incidence of fall-related injuries differed significantly according to gender. Women accounted for 71.2% of the respondents who had experienced fall-related injuries, and men accounted for 28.8% (c2 ¼ 7.97, p ¼ 0.022). The incidence of falls however did not differ according to age, education, income, living arrangement, or body mass index. Older adults who had experienced fall-related injuries had higher rates of morbidity in terms of stroke (7.9% vs. 3.4%, c2 ¼ 7.04, p ¼ 0.013) and depression (4.7% vs. 2.1%, c2 ¼ 3.82, p ¼ 0.049). However, no significant differences were observed for arthritis or diabetes mellitus. Of the total respondents, 1404 (49.3%) had sarcopenia. Subjects with sarcopenia were significantly more likely to have experienced fall-related injuries (63.3% vs. 48.7%, c2 ¼ 5.96, p ¼ 0.008). Table 1 Characteristics of participants (N ¼ 2848). Variables
Total (n ¼ 2848)
Fallers (n ¼ 120)
Non fallers (n ¼ 2728)
c2/t
p
n (%)
Data analysis Descriptive statistics were used to analyze subjects’ sociodemographic characteristics. In light of the inherent statistical complications involved in multistage, complex survey designs, the investigators followed the guidelines of KNHANES for the analysis of sample weights. By using these weights appropriately, the stratification and clustering of the design were incorporated into the analyses to ensure appropriate estimates and standard errors.22 t-tests and chi-square tests were employed to test differences between subjects who had and had not experienced fall-related injuries. To assess whether sarcopenia had an independent influence on fall-related injury (above and beyond the influences of potential confounders), we applied a hierarchical multiple logistic regression analysis. The regression analysis was used to estimate the relationship between sarcopenia and the risk of fall-related injuries after adjusting for covariates.23 In model 1, we included demographic variables that may be associated with falls or sarcopenia3,4,24: age, gender, educational difference, income, and marital status. In model 2, we additionally incorporated covariates related to disease morbidity: stroke, arthritis, diabetes, and depression.1,25 Finally, model 3 included each covariate in model 2, as well as sarcopenia status, which was thereby adjusted for demographic
Age, year (mean (SE)) 73.17 (0.14) 73.41 Gender Women 1675 (58.8) 85 Men 1173 (41.2) 35 Education Less than elementary 2047 (71.9) 89 school graduate 313 (11.0) 14 Middle school graduate High school graduate 327 (11.5) 14 More than a college 159 (5.6) 3 graduate Income quartile Low 772 (27.1) 37 Middle-low 722 (25.3) 27 Middle-high 702 (24.7) 28 High 652 (22.9) 28 Living arrangement Living alone 478 (16.8) 25 Living with others 2370 (83.2) 95 Morbidity of disease Stroke 103 (3.6) 9 Arthritis 803 (28.2) 41 Diabetes 501 (17.6) 24 Depression 63 (2.2) 6 Sarcopenia 1404 (49.3) 76 Body mass index 23.72 (0.10) 24.08 (mean (SE))
(0.49) 72.93 (0.13) 0.97 0.335 (71.2) (28.8)
1590 (58.3) 7.97 0.022 1138 (41.7)
(73.9)
1958 (71.8)
(11.7)
301 (11.0) 2.05 0.574
(11.6) (2.7)
313 (11.5) 156 (5.8)
(31.2) (22.3) (23.1) (23.4)
735 695 674 624
(21.0) (79.0)
(27.0) (25.5) 1.33 0.764 (24.7) (22.9)
453 (16.6) 1.66 0.287 2275 (83.4)
(7.9) 94 (33.8) 762 (19.9) 477 (4.7) 57 (63.3) 1328 (0.33) 23.71
(3.4) (28.0) (17.5) (2.1) (48.7) (0.10)
7.04 1.95 0.46 3.82 5.97 1.16
0.013 0.307 0.499 0.049 0.008 0.237
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We used hierarchical multiple logistic regression analysis to estimate the effect of sarcopenia on the risk of fall-related injuries, after adjusting for sociodemographic variables and chronic diseases (Table 2). According to model 1, the OR for fall-related injuries was significantly higher for women than for men (OR ¼ 1.78, 95% confidence interval [CI] ¼ 1.05e3.03). In model 2, morbidity in terms of stroke significantly increased the OR for fall-related injuries (OR ¼ 2.62, 95% CI ¼ 1.24e5.55); however, arthritis, diabetes mellitus, and depression were not significant predictors. Female gender was not a significant predictor of fall-related injuries in model 2 (OR ¼ 1.77, 95% CI ¼ 0.99e3.16). Finally, in model 3, which controlled for sociodemographic variables and disease morbidity, sarcopenia was the significant predictor affecting fall-related injuries. Among this older population, the risk of fall-related injuries was higher for individuals with sarcopenia than for those without sarcopenia (OR ¼ 1.59, 95% CI ¼ 1.02e2.49). Morbidity in terms of stroke also significantly increased the OR for fall-related injuries (OR ¼ 2.63, 95% CI ¼ 1.05e6.59). Discussion In the current study, we evaluated the influence of sarcopenia on fall-related injuries in older community-dwelling Korean adults. Our findings demonstrated a high prevalence of sarcopenia among older Korean adults, accounting for 49.3% of the population. Older Korean adults with sarcopenia had a higher rate of fall-related injuries than did their counterparts without sarcopenia. Consistent with the results of a previous study among elderly Italians, sarcopenia was shown to have a strong effect on fall-related injuries, after adjusting for other sociodemographic variables and disease morbidity.16 In the current study, the incidence of fall-related injuries was 4.3%, which was similar to the 4.9% incidence that was reported in a recent study conducted in the United States.26 However, the incidence was far lower than that reported by a previous study, which found that 15.2% of older Korean adults had received medical attention and 28.9% had been hospitalized as a result of falls.4,5 The discrepancy between these fall-related injury rates may be attributable to differences in the quantification of falls, such as the assessment of fall-related injuries treated by health care providers rather than the incidence of falls. Additionally, the discrepancy may have resulted from the current study’s use of representative community samples.5,27
Table 2 Hierarchical multiple logistic regression analysis on influence of sarcopenia on fall injuries (N ¼ 2848). Model 1
Model 2
Model 3
1.02 (0.98e1.05) 1.77 (0.99e3.16)
1.01 (0.97e1.05) 1.28 (0.67e2.45)
1.08 (0.84e1.39) 0.99 (0.77e1.23) 1.21 (0.65e2.23)
1.10 (0.82e1.49) 0.97 (0.73e1.29) 1.11 (0.48e2.56)
2.62 0.99 1.13 0.49
2.63 0.94 0.85 0.41 1.59
OR (95% CI) Sociodemographic Age 1.02 (0.98e1.05) Gender (female 1.78 (1.05e3.03)* vs. male) Education 1.08 (0.84e1.39) Income 0.98 (0.77e1.25) Living arrangement 1.16 (0.62e2.19) (living alone vs. living with others) Morbidity of chronic diseases Stroke Arthritis Diabetes Depression Sarcopenia *p < 0.05.
(1.24e5.55)* (0.59e1.68) (0.71e1.79) (0.20e1.21)
(1.05e6.59)* (0.50e1.76) (0.46e1.58) (0.07e2.57) (1.02e2.49)*
3
Using the indicator of ASM/weight, which reflects the relative quantity of muscle mass as a component of the total body composition,19 the high prevalence of sarcopenia (49.3%) in the current study was comparable to the results of previous studies in Korea and the United States. These previous studies reported prevalence rates of 38% and 52% in men and 63% and 69% in women, respectively.21,28 However, the prevalence of sarcopenia in our study was much higher than that reported in studies measuring sarcopenia using the ASM/height2 indicator, which reflects the absolute quantity of muscle mass, disregarding body composition.15 The latter study concluded that only 6.3% and 4.1% of older Korean men and women, respectively, had sarcopenia.29 The relationship between sarcopenia and fall-related injuries in the current study may be explained by the critical role of sarcopenia in the frailty process. Frailty plays a role in the poor outcomes of falls, such as various traumas, functional decline, and disability.12,13,28,30 Early seminal studies on sarcopenia reported that reduced muscle mass may result in low physical performance, a decline in mobility, and functional impairment,31e34 which can be regarded as distinctive characteristics of frailty. Therefore, we believe that fall-related accidents may occur as results of decreased agility, decreased flexibility, and delayed reactions, which themselves result from sarcopenia. Accordingly, the current study provides evidence of the need for fall prevention interventions that reduce risk factors for sarcopenia. In particular, there is a need for interventions promoting physical activities that increase muscle mass among older adults. Regarding the successful prevention of fall-related injuries in the community, the current study’s findings underscore the importance of identifying older adults with sarcopenia and implementing targeted approaches in this subgroup. The significant relationship between sarcopenia and fall-related injuries provides suggestions for elements that should be included in multi-factorial interventions, including physical activity and adequate nutrition programs.16,35 There are various means of slowing the decline in muscle mass that is associated with aging. Specifically, it may be valuable to increase health care providers’ awareness of sarcopenia in older adults. Further, it may be worthwhile to implement structured exercise programs (including progressive resistance or power training) and nutritional interventions (including sufficient protein and additional caloric intake).36 The current study had some limitations. First, it is possible that the findings would have differed if we had used a different method to quantify sarcopenia. In the current study, we quantified sarcopenia using the ASM/weight indicator, which overcomes important limitations of the ASM/height2 indicator. Indeed, the ASM/height2 indicator insufficiently accommodates reduced mobility in older adults37 and does not provide an appropriate definition of sarcopenia in Asians.21 Second, we employed secondary data analysis, which might have made the measurement of some key variables difficult, possibly influencing the results. When assessing falls, we measured fall-related injury rather than fall accidents because we could only obtain information on fallrelated injuries from the existing KNHANES data. Despite these limitations, our study has the advantage of using a representative sample of the Korean population. Our results suggest that sarcopenia is a critical problem among the elderly and must be considered by health care providers in preventing fall-related injuries in the community. In conclusion, sarcopenia is an important factor that contributes to the increased risk of fall-related injuries among communitydwelling elderly adults in Korea. Therefore, physical activity programs, nutritional programs, and other such interventions should be considered first for the prevention of fall-related injury.38e40 Further, interventions such as physical activity and nutritional
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