Citius, Fortius? Cohort, inflammation and trajectories of gait speed and grip strength in older Britons

Abstract

Although the cost of long term care of physical disabilities is considerable, little is known about individual trajectories of physical function (measured by gait speed and grip strength) that preceded the process of disablement. Moreover, studies on trajectories of health function have often ignored cohort composition, precluding evidence of secular improvement. And few have explored the role of chronic inflammation on older people's physical function trajectories. Using the English Longitudinal Study of Ageing 2004-2013 we derived trajectories of gait speed and grip strength of Britons aged 50 and older and investigated the effect of inflammation. Then we drew trajectories for different cohorts to seek evidence of secular improvement. We uncovered a complex gradient of improvement in trajectories of physical function that depends on sex and maximum versus normal capacity. In conclusion, accounting for the cohort composition of older people can materially modify the future cost of long term care.