Multimorbidity and Health-Related Quality of Life in Korean Older Adults: A Mediation Analysis on Handgrip Strength

Background: The influence of handgrip strength on the relationship of multimorbidity with health-related quality of life (HRQoL) is unknown in geriatric populations. The current study investigated whether or not handgrip strength mediates the association between multimorbidity and HRQoL in a representative sample of Korean adults (3139 men/3753 women) aged 65 years and older. Methods: The data obtained from the 2014-2019 Korea National Health and Nutrition Examination Survey (KNHNES) were used in the current study. The EuroQoL group was used to assess HRQoL. Multimorbidity was defined as co-existence of more than one of the 26 diagnosed diseases specified in the KNHNES. A digital hand dynamometer was used to measure handgrip strength. The covariates included in this study were age, gender, parameters of body fatness, socio-demographics, and parameters of health behaviors. Results: Analysis of variance showed that HRQoL was inversely associated with number of chronic conditions and positively with relative handgrip strength. Particularly, a mediation analysis using the PROCESS macro in SPSS-PC showed that relative handgrip strength partially mediates the influence of multimorbidity on HRQoL. Bootstrapping showed that the indirect effect of comorbidity on HRQoL via relative handgrip strength was significant (p < 0.001) even after adjustments for all the covariates, explaining 8.1% the total effect. Conclusions: The findings of the study emphasize the importance of health-related physical fitness while managing and/or treating multiple chronic conditions for better HRQoL in geriatric populations.