Mediation and Moderation of Adiposity Indicators for the Association Between Grip Strength and Cardiovascular Disease Risk Scores

Grip Strength, Anthropometric Indices, and Their Combination in Screening for Metabolic Syndrome in the Korean Population

Background: Metabolic syndrome (MS) is a cluster of cardiometabolic risk factors for future diabetes and cardiovascular diseases, and low grip strength (GS) is associated with an increased risk of MS. However, the index (among absolute GS, relative GS, and anthropometric indices) that is more strongly associated with MS has not been conclusively identified. Therefore, the objective of the present study was to simultaneously examine the associations of MS with relative and absolute GS and anthropometric indices in a Korean population. Methods: In this large-scale cross-sectional study, we used data from the Korean National Health and Nutrition Examination Survey (KNHANES). A total of 20,915 subjects were included in the statistical analyses. Complex sample binary logistic regression models were used to analyze the associations between MS and indices such as the waist-to-height ratio (WHtR), body mass index (BMI), and absolute and relative GS. Results: The prevalence of MS was 40.48% in men and 34.4% in women. The mean GS values in the healthy group and MS group were 38.06 ± 0.13 and 38.06 ± 0.15 years for men (p = 0.980) and 22.72 ± 0.07 and 21.19 ± 0.11 years for women (p < 0.001), respectively. Among all the indices, the WHtR was the index most strongly associated with MS in men. Among the GS indices, the GS/weight index was closely associated with MS, and the magnitude of this association was stronger than that of the absolute GS index. In women, the WHtR was the most related index to MS among all the indices. Among the GS indices, the GS/weight and GS/BMI indices were strongly associated with MS, and the magnitudes of these associations were much greater than those of the absolute GS index. Conclusions: Although absolute and relative GS indices are strongly associated with MS in the Korean population, the strongest association was observed for the simple anthropometric index (WHtR).

Mediation of Grip Strength on the Association Between Self-Rated Health and Estimated Cardiovascular Disease Risk

Background: Grip strength and self-rated health (SRH) have been reciprocally related, and each has been associated with cardiovascular disease (CVD) risk. However, the pathway between SRH and grip strength in the association with CVD risk remains uncertain. This cross-sectional study evaluated whether grip strength mediates the association between SRH and estimated CVD risk. Methods: In 15,930 Koreans 40-79 years of age without CVD history from the 2014 to 2018 Korea National Health and Nutrition Examination Survey, the risk of 10-year atherosclerotic cardiovascular disease (ASCVD) was calculated using Pooled Cohort Equations. Relative grip strength (RGS) was defined as measured grip strength divided by body mass index. SRH was assessed using a single questionnaire. Results: After adjusting for the covariates, males in the non-highest RGS tertiles, the fair/poor/very poor SRH groups, or the other joined categories of RGS tertiles and SRH groups (except the highest RGS tertile and good SRH group) had higher odds for 10-year ASCVD risk ≥7.5% than the reference group. The ASCVD risk was higher in females in the lowest RGS tertile, the poor/very poor SRH group, or the combined category of lowest RGS tertile and poor SRH group than the reference group. RGS significantly mediated the relationship between better SRH and the lower ASCVD risk (indirect effect: β = -0.078, 95% CI [-0.097 to -0.060], P < 0.05) and reduced the total effect of SRH on the ASCVD risk (direct effect: β = -0.225, t = -3.203, P = 0.001). RGS mediated 26% of the association between SRH and ASCVD risk. Conclusion: Grip strength may have a mediating role in the relationship between SRH and the estimated 10-year risk of ASCVD.