The association between handgrip strength and future health outcomes does not differ if grip strength is used in absolute or relative terms: a prospective cohort study

Background: higher grip strength is associated with better health outcomes. The optimal way to report grip strength (i.e. absolute vs. relative) for prediction, however, remains to be established. Methods: in participants (aged 37–73 at baseline) from the UK Biobank, we examined the associations of grip strength, expressed in absolute terms (kilograms) and relative to anthropometric variables, with mortality and disease incidence, after exclusion of the first 2 years of follow-up, and compared risk predictions scores of handgrip strength when differentially expressed. Results: of the 356 721 participants included in the analysis 6,234 died (1.7%) and 4,523 developed CVD (1.3%) over a mean follow-up of 5.0 years (ranging from 3.3 to 7.8) for mortality and 4.1 years (ranging from 2.4 to 7.0) for disease incidence data. As expected, baseline higher grip strength was associated with lower risk of all-cause and cause specific mortality and incidence. These associations did not meaningfully differ when grip-strength was expressed in absolute terms, vs. relative to height, weight, fat-free mass, BMI, fat-free mass index and fat-free mass, or as z-scores. Similarly the different ways of expressing grip strength had little effect on the ability of grip strength to improve risk prediction, based on C-index change, of an office-based risk score. Conclusions: the ability of grip strength to predict mortality is not altered by changing how it is expressed