한국 노인에서 근육감소증의 유병률과 관련 요인

Abstract

OBJECTIVES: To establish the prevalence of sarcopenia in Korean elderly population and to determine whether there are any associations between physical activity, nutritional status and sarcopenia.

DESIGN: A cross-sectional, population-representative sample.

SETTING: Nationally representative cross-sectional survey using data from the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV).

PARTICIPANTS: Eight thousand eight hundred eighty two KNHANES IV participants aged 19 and older who completed the body composition using a Dual energy x-ray absorptiometry (DXA) was measured since the last half of year 2008.

MEASUREMENTS: The prevalence of sarcopenia and the relationship between sarcopenia and risk factors were examined in 2725 adults aged 60 and older (1156 men and 1569 women). DXA was used to measure whole and regional body composition. Appendicular skeletal muscle mass (ASM) was calculated as the sum of skeletal muscle in arms and legs. First, sarcopenia was defined as the ASM/Ht2 less than two standard deviations (SD) below the sex-specific normal mean for younger reference group. Alternatively, residual method was defined as the reference values less than 2 SD below the sex-specific normal mean for younger reference group. Residuals were calculated by the difference between measured ASM and ASM that is predicted by linear regression analysis used to model the relationship between ASM as a dependent variable, and height (meters) and total fat mass (kg) as the independent variables. To determine whether there are any associations between physical activity, nutritional status and sarcopenia, sarcopenia was defined as the ASM/Ht2 less than two standard deviations (SD) below the sex-specific normal mean for younger reference group in Korean elderly men and the lowest 20% of the distribution of ASM/Ht2 in Korean elderly women.

RESULTS: The weighted prevalence of sarcopenia in Korean men and women aged more than 60 years using the 2 SD for ASM/Ht2 in the young reference group was 9.0% (6.9~11.0%) and 0.0%, respectively. The prevalence of sarcopenia increased significantly with age in men. Using the below 2 SD of the residuals for ASM adjusted fat mass and height in the young reference group, the weighted prevalence of sarcopenia was 5.0% (3.1~6.9%) in men and 1.0% (0.4~1.7%) in women. In Korean elderly population, mean body mass index was lower in subjects with sarcopenia than those without sarcopenia (19.2? 2.1 vs 23.8? 2.7 in men, 21.3? 2.4 vs 24.9? 3.0 in women, P<0.001, respectively), but, mean age was older (72.6? 6.9 vs 68.6? 6.1 in men, 71.3? 7.1 vs 68.8? 6.1 in women, P<0.001, respectively)in subjects with sarcopenia. The proportion of family income and education status were much higher in subject without sarcopenia compared to subjects with sarcopenia in Korean elderly men (P<0.001, respectively). Adjustment for total MET-min/week, flexibility (OR=0.55, 95% CI=0.34?0.90) and strength (OR=0.39, 95% CI=0.21?0.75) exercise are associated with sarcopenia in Korean elderly men (Table 6-1), but any type of physical activity or flexibility or strength exercise are not associated in Korean elderly women (Table 6-2). When physical activity was categorized according to IPAQ classification, prevalence of sarcopenia were much higher in low (14.5% in men, 21.2% in women) or moderate (9.9% in men, 22.0% in women) physical activity group than high physical activity group (6.1% in men, 14.7% in women) in Korean elderly men (P<0.001) and women (P=0.017). Prevalence of sarcopenia relatively decreased as the quartile of the energy intake (Q1 17.3%, Q2 10.0%, Q3 6.9%, Q4 5.2% in men, Q1 26.7%, Q2 21.7%, Q3 17.6%, Q4 13.9% in women) or protein intake (Q1 18.7%, Q2 8.7%, Q3 8.3%, Q4 3.8% in men, Q1 28.2%, Q2 18.8%, Q3 17.3%, Q4 15.8% in women) increased in both sexes(P<0.001, respectively). In logistic regression models, sarcopenia was associated with high physical activity (OR=0.28, 95% CI=0.14?0.54 in men, OR=0.59, 95% CI=0.39?0.89 in women) and the highest quartile of protein intake (OR=0.32, 95% CI=0.14?0.74 in men, OR=0.49, 95% CI=0.32?0.75 in women) after adjusting for age, body mass index, smoking habit, alcohol drinking, family income and education status.

CONCLUSIONS: Although the prevalence of sarcopenia in Korean elderly women is low, reduced skeletal muscle mass in Korean elderly population is significantly associated with physical activity and protein intake. Based on increased awareness of sarcopenia in elderly population and widespread use of tools for screening and assessment, it is necessary to identify dietary strategies, lifestyle changes and treatments that can prevent or delay the onset of sarcopenia.