Impact of sarcopenic obesity and physical inactivity on mortality in Korean older adults: a population-based longitudinal study

Abstract

OBJECTIVES: To investigate the association between the 4 body composition status of sarcopenic obesity (nonsarcopenic nonobesity; S-O-, nonsarcopenic obesity; S-O+, sarcopenic nonobesity; S+O-, sarcopenic obesity; S+O+) and the mortality risks, and to compare the relative mortality risks of Korean elderly who met the 2018 Physical Activity Guidelines with elderly who did not meet the recommendations. METHODS: 2,781 participants aged over 65 years in the Korean National Health and Nutrition Examination Survey 2008-2011 (KNHANES IV-V) were included in this study. Sarcopenia was defined by the value of appendicular skeletal muscle mass (ASM) divided by square of height (ht2) <7.0kg/m2 and <5.4kg/m2 for women. Obesity was defined as waist circumference of ≥90cm for men and ≥85 for women. Physical activity was categorized by adherence to aerobic and muscle-strengthening physical activity guidelines. For mortality, we merged mortality information from Korea Centers for Disease Control and Prevention with KNHANES IV-V data to conduct this study. Cox proportional hazards models were used to examine the relative mortality risks of Korean elderly aged over 65 years according to groups for sarcopenia and obesity, using data from the 2008-2011 KNHANES and linked mortality records for deaths occurring in 2007–2015. RESULTS: There were 629 deaths during follow-up. S+O+ (HR 1.58; 95% CI 1.16-2.17) and S+O- (HR 1.34; 95% CI 1.09-1.63) demonstrated significantly higher risk of mortality compared to S-O- reference group after adjusting for covariates. However, S-O+ group (HR 1.03; 95% CI 0.84-1.27) did not show significant association with mortality. Meeting the recommendations for aerobic and muscle-strengthening physical activity respectively was associated with substantial survival benefits when compared to S-O- reference group, with all values being invalid for hazard ratios among all groups. Not adhering to the guideline was related to increased mortality risk in most of the groups, when compared to S-O- participants meeting the physical activity guideline reference group. All groups for sarcopenic obesity demonstrated significantly increased mortality risk in group for not adhering to guidelines to muscle-strengthening physical activity. In not adhering to aerobic guideline group, S+O- (HR 1.38; 95% CI 1.04-1.84) and S+O+ group(HR 1.53; 95% CI 1.04-2.26) showed increased risk for mortality, while values for nonsarcopenic nonobese and nonsarcopenic obese group not being significant in the analysis. CONCLUSION: Subjects with S+O+ were associated with a 58% increased risk of mortality, and 34% for S+O- group when compared to S-O- group; S-O+ groups not showing significant association with mortality. Furthermore, not adhering to physical activity guidelines was associated with increased mortality risks among the Korean elderly, after controlling for lifestyle variables and comorbidities. Efforts to promote healthy aging should focus on preventing obesity, maintaining muscle mass, and engaging in aerobic and muscle-strengthening activities for recommended amount.