Mortality in the Hertfordshire Ageing Study: association with level and loss of hand grip strength in later life.

Background Weak hand grip strength in later life is a risk factor for disability, morbidity and mortality and is central to definitions of sarcopenia and frailty. It is unclear whether rate of change in grip strength adds to level of grip strength as a risk factor for poor ageing outcomes. Methods Study participants were 292 community-dwelling men and women whose grip strength was measured during the 1994/5 (average age 67) and 2003/5 (average age 76) phases of the Hertfordshire Ageing Study, UK. Individual rate of change in grip strength was estimated using a residual change method. Mortality was followed-up to 2011 (42 men and 21 women died). Results Average grip strengths in 2003/5 were 38.4kg (standard deviation [SD] 8.1) and 23.7kg (SD 6.6) for men and women respectively. Average annualised rates of change in grip strength (2003/5 minus 1994/5) were modest owing to a healthy-participant effect (men: -0.12kg/year SD 0.71; women: 0.08kg/year SD 0.54) but varied widely. Mortality risk varied according to level and rate of change in grip strength (p=0.03); death rates per 100 person years of follow-up were 6.7 (95%CI 4.6,9.6) among participants who lost grip over time and had low grip in 2003/5, in contrast with 0.8 (95%CI 0.1,5.8) among participants whose grip changed little over time and remained high in 2003/5. Conclusions Levels of grip strength in later life should be considered in conjunction with estimates of change in grip strength identified by repeat measurement over time. Normative data for longitudinal change in grip strength are required.