Weak Grip Strength Correlates with Increased Mortality Risk in Old Age
The characteristic loss of muscle mass and strength that occurs with age, sarcopenia, is accompanied by increased mortality risk where it is more pronounced. This may be because the causes of sarcopenia, such as loss of stem cell function, chronic inflammation, and so forth, have many other detrimental consequences, contributing to numerous fatal age-related conditions. This study illustrates the point, providing evidence for a weak hand grip strength to correlate with a shorter remaining life expectancy.
Muscle strength is a powerful predictor of mortality that can quickly and inexpensively be assessed by measuring handgrip strength (HGS). What is missing for clinical practice, however, are empirically meaningful cut-off points that apply to the general population and that consider the correlation of HGS with gender and body height as well as the decline in HGS during processes of normal ageing. This study provides standardised thresholds that directly link HGS to remaining life expectancy (RLE), thus enabling practitioners to detect patients with an increased mortality risk early on.
Relying on representative observational data from the Health and Retirement Study, the HGS of 8,156 survey participants aged 50-80 years was z-standardised by gender, age and body height. We defined six HGS groups based on cut-off points in standard deviation (SD) from the mean; we use these as predictors in survival analyses with a 9-year follow-up and provide RLE by gender based on a Gompertz model for each HGS group.
Even slight negative deviations in HGS from the reference group with have substantial effects on survival. RLE among individuals aged 60 years with standardised HGS of up to -0.5 SD from the mean is 3.0/1.4 years lower for men/women than for the reference group, increasing to a difference of 4.1/2.6 years in the group with HGS of -0.5 SD to -1.0 SD from the mean. By contrast, we find no benefit of strong HGS related to survival. Survival appears to decrease at much higher levels of muscle strength than is assumed in previous literature, suggesting that medical practitioners should start to become concerned when HGS is slightly below that of the reference group.