Disability free life expectancy: a simulation study of scenarios to extend healthy years and reduce inequalities

BACKGROUND: The gap in Disability-Free Life Expectancy between affluent and deprived areas of England is stark, at over 15 years. Successive governments have recognised the need to narrow this and extend the years of life spent without disability, but there is little evidence outlining how large an intervention must be to achieve meaningful gains. This study examines intervention scenarios to (i) extend Disability-Free Life Expectancy and (ii) reduce socioeconomic inequalities in Disability-Free Life Expectancy, among older people in England. METHODS: We applied multistate modelling to longitudinal data on 16 899 individuals, aged 50 + in England, incorporating disability data from three cohort studies: the English Longitudinal Study of Ageing, the Cognitive Function and Ageing Study II, and the Newcastle 85 + Study. Simulations assessed how reducing the risk of disability associated with age and area-based socioeconomic deprivation could extend Disability-Free Life Expectancy. In these simulations, deprivation-targeted interventions reduced the excess disability risk and differential recovery observed in people living in the 20% most deprived areas. Age-targeted interventions reduced the age-related increase in disability risk and the corresponding decline in recovery. RESULTS: Interventions targeted solely at the most deprived quintile yielded modest Disability-Free Life Expectancy gains (up to 2.8 years for women and 2.3 years for men, in deprived areas only). Interventions targeting age-related disability risk alone were associated with increases in Disability-Free Life Expectancy of 6.3 to 8.7 years under a 40% reduction in age-related disability risk, but exacerbated the gap between the most and least deprived populations. Interventions addressing both age- and deprivation-associated risks demonstrated the greatest potential. A 30% decrease in the age-based probability of disability, and commensurate increases in recovery from disability, alongside removal of deprivation-associated inequalities, increased Disability-Free Life Expectancy by 4.8 to 8.6 years for men and women aged 50, with women living in deprived areas benefiting most. CONCLUSIONS: Extending Disability-Free Life Expectancy while reducing socioeconomic inequality is difficult, but possible by tackling both age- and deprivation-related risks. Taken on their own, age-based interventions risk increasing inequalities, as they disproportionately benefit people living in less deprived areas.