Birth-cohort trends in older-age functional disability and their relationship with socio-economic status: Evidence from a pooling of repeated cross-sectional population-based studies for the UK.

We examine birth-cohort trends behind recent changes in the prevalence of functional disability in the older population living in private households in the United Kingdom (UK). By using three different socio-economic indicators available in the nationally representative cross-sectional data on older individuals interviewed between 2002 and 2012 in the Family Resource Survey (FRS) (96,733 respondents), we investigate the extent to which the overall trends have been more favourable among more advantaged than disadvantaged socioeconomic groups. Compared to the cohort of people born in 1924, successive cohorts of older men have lower odds of having at least one functional difficulty (FD), whereas no significant trend was found for women. Among people with at least one FD, however, the number of disabilities increases for each successive cohort of older women (incidence rate ratio 1.027, 95% confidence interval 1.023 to 1.031, P < 0.001) and men (incidence rate ratio 1.028, 95% confidence interval 1.024 to 1.033, P < 0.001). By allowing interactions between birth cohort and SES indicators, a significant increasing cohort trend in the number of reported FDs was found among older men and women at lower SES, whereas an almost stable pattern was observed at high SES. Our results suggest that the overall slightly increasing birth-cohort trend in functional difficulties observed among current cohorts of older people in the UK hides underlying increases among low SES individuals and a relative small reduction among high SES individuals. Further studies are needed to understand the causes of such trends and to propose appropriate interventions. However, if the SES differentials in trends in FDs observed in the past continue, this could have important implications for the future costs of the public system of care and support for people with care needs.