Does the association between physical capability and mortality differ by deprivation? Findings from the UK Biobank population-based cohort study

Background To investigate whether the excess risk of adverse health outcomes associated with a lower physical capability in adulthood differs by deprivation levels. Methods 279,030 participants from the UK Biobank were included. Handgrip strength and walking pace were the exposures. All-cause mortality, CVD mortality and incidence were the outcomes. Townsend deprivation index was treated as a potential effect modifier. The associations were investigated using Cox-regression models with years of follow-up as the time-varying covariate. Results A significant interaction between deprivation and handgrip strength was found for all-cause mortality (p = 0.024), CVD mortality (p = 0.006) and CVD incidence (p = 0.001). The hazard ratio for all-cause mortality was 1.18 [1.09; 1.29] per 1-tertile higher level of grip strength in the least deprived group, whereas it was 1.30 [1.18; 1.43] in the most deprived individuals. Similar results were found for CVD mortality and incidence per tertile increment in handgrip strength in the least and most deprived quintiles, respectively. No significant interactions between deprivation and walking pace were found for any of the outcomes. Conclusion Low handgrip strength is a stronger predictor of morbidity and mortality in individuals living in more deprived areas.