Handgrip Strength and Body Mass Index Independently Predict All-Cause Mortality in Japanese Older Adults: An 8-Year Cohort Study

Background: This study explores the relationship between muscle strength, as measured by handgrip strength (HGS), and all-cause mortality in Japanese community-dwelling individuals, considering factors such as body mass index (BMI). Methods: The research involved 785 males and 952 females, aged 69 +/- 11 and 69 +/- 9 years, respectively, who were part of the Nomura cohort study initiated in 2014 and followed up for 8 years. The Japanese Basic Resident Registry provided data on adjusted relative hazards for all-cause mortality. The data were subjected to a Cox regression analysis using a time variable of age and confounding risk factors. Results: Among the 1,737 participants who could be followed, a total of 165 (5.5%), comprising 98 males (12.5%) and 67 females (7.0%), were confirmed deceased. When comparing mortality risks among groups based on handgrip strength (HGS) tertiles and stratified by BMI category, adjusted mortality risks were observed in individuals within the first tertile of HGS (men < 31.0 kg; women < 19.7 kg) and a BMI of < 18.5 kg/m2 [hazard ratio, 5.77; 95% confidence interval, 3.08-10.8] and 18.5-24.9 kg/m(2) (1.88; 1.20- 2.98), compared to those within the second and third HGS tertiles (men >= 31.0 kg; women >= 19.7 kg) and a BMI of >= 18.5-24.9 kg/m(2). Conclusion: These findings emphasize the HGS is an important tool for prognostic of survival along with low category of BMI, irrespective of other potential confounding factors.