Association of Sarcopenic Obesity with Cardiovascular Diseases in Korean Adults

Abstract

Introduction: As the body composition changes with aging, many crucial events affect the health status of individuals. Sarcopenia is one of the degenerative change and defined as an age-related decrease in skeletal muscle mass and strength. Therefore, sarcopenia may lead to harmful conditions, for example, physical disability and frailty. In addition, obesity has been the main health problem in many countries over the world. Many previous studies have supported the evidence that obesity has the associations with various disease including hypertension, diabetes mellitus, cancer and coronary artery disease. Sarcopenic obesity represents the age-associated loss of skeletal muscle mass coupled with the increment of adiposity, however, an exact definition of consensus has not been established yet. Since the fact that sarcopenia and sarcopenic obesity do really affect developing cardiovascular disease was not confirmed except for obesity, this study would contribute to recognizing whether the relationship is significant.

Methods: This study used data from the Korean Genome and Epidemiology Study (KoGES), a prospective study, which involves follow-up biennially and composed of several kinds of cohorts. The main exposures of this study are sarcopenia, obesity, and sarcopenic obesity. In this study, fat-free mass index (FFMI) measured by bioelectrical impedance analysis (BIA) was used to classify sarcopenia and if subjects were in the lowest two-fifths of the FFMI, they were considered as who had sarcopenia referred to the related study. For classification for obesity, body mass index (BMI) was used. Subjects who had BMI≥25 were classified as obese. Furthermore, participants were classified as sarcopenic obese if they had not only sarcopenia but also obesity. The outcome of this study consisted of incidence of cardiovascular disease (CVD). Moreover, to consider other variables that may influence the results, sociodemographic, behavioral, and risk factors for CVD were also included in the analysis. To examine the association between exposure and outcome, extended Cox proportional hazards regression was conducted with the optimal reference group.

Results: As divided into four groups by FFMI and BMI, 28.8% of subjects were classified as a normal group. In addition, 28.9% were sarcopenic, 40.0% were obese, and only 2.3% were sarcopenic obese. The proportion of woman about the sarcopenia, obesity, and sarcopenic obesity is larger than that of man. In a behavioral aspect, normal group tended to have more alcohol and smoking. In model 1, sarcopenic group had a less risk of overall CVD than normal group (HR = 0.71, 95% CI = 0.53-0.96), but obese group had a higher risk of both overall CVD (HR = 1.57, 95% CI = 1.21-2.04) and MI (HR = 2.21, 95% CI = 1.17-4.19). Furthermore, the sarcopenic obese group had much higher risk than obese group (HR = 4.11, 95% CI = 1.25-13.45). In model 2, most of the results were same as the estimates of model 1 except for the effect of sarcopenia on CAD (HR = 0.60, 95% CI = 0.37-0.97). The results of model 3 were similar to those of model 1, so that represented that subjects with sarcopenia were less likely to contract overall CVD (HR = 0.72, 95% CI = 0.53-0.98), but obesity (HR = 2.42, 95% CI = 1.22-4.79) and sarcopenic obesity (HR = 3.86, 95% CI = 1.16-12.8) has higher risks of MI than normal status. Obesity and sarcopenic obesity were more strongly associated with MI in the female. In the older age group, it was more clearly identified that obesity was related to contracting overall CVD (Model 1: HR = 2.15, 95% CI = 1.38-3.36

Model 2: HR = 2.31, 95% CI = 1.45-3.68

Model 3: HR = 2.22, 95% CI = 1.37-3.59) and CAD (Model 1: HR = 2.04, 95% CI = 1.07-3.92

Model 2: HR = 2.64, 95% CI = 1.33-5.25

Model 3: HR = 2.49, 95% CI = 1.21-5.12).

Conclusion: This study showed that suspicious determinants including sarcopenia, obesity, and sarcopenic obesity may affect developing CVD either positively or negatively in Korean adults. Sarcopenic obesity and obesity itself was positively associated with some of CVD. However, sarcopenia itself was negatively related to CVD. The present study may show another perspective to sarcopenia and its impact, although the measurement of muscle mass is limited and absence of the evaluation for the function of muscle needs to be supplemented. The findings in this study may suggest further studies with more accurate measurements of exposure variables and other prospective cohort focused on CVD to more clearly identify this association.