Background Frailty is a measure of a person’s vulnerability to health stressor events resulting from an age-related decline in reserves. Frail people have greater need of health and social care, a concern for an ageing population. Understanding how the onset of frailty differs between socio-economic groups will help health and care providers plan for increased demand and highlight population groups who could most benefit from interventions to reduce frailty. We aimed to calculate the frailty-free, frail and total life expectancies of adults aged over 50 using data from the English Longitudinal Study of Ageing (ELSA). Associations with wealth, deprivation, education, marital status and gender were investigated.

Methods Survey data from ELSA waves 1–9 (2002–2019) was used to follow the frailty trajectories of individuals. Longitudinal data for 11,423 individuals aged 50+ were available wave 1. Using a frailty index, ELSA participants were categorised into non-frail and frail states. A multistate model assessed the risk of individuals transitioning between states or dying. Transitions were associated with participant’s socio-economic characteristics and converted to life expectancies. Models were fit in R, with the MSM and ELECT packages. Sensitivity analyses evaluating cohort effects and relaxing the Markov assumption in the multistate model did not significantly alter the model fit.

Results Increased wealth, reduced deprivation, more education, and marriage are all associated with increased frailty-free and total life expectancies, and reduced frail life expectancies. Wealth is the most important socio-economic indicator of frailty-free life expectancy. 70-year-old females and males have similar frailty-free life expectancies (female: 11.8 [11.5–12.1] years; male: 11.7 [11.4–12.1] years) however males have shorter frail life expectancies (female: 6.1 [5.8–6.3] years; male: 3.7 [3.4–3.9] years). At age 50, large inequalities in frailty-free life expectancies exist between the wealthiest, least deprived population (females: 36.1 [35.1–37.0], males: 34.6 [33.7–35.4] years) and the least wealthy, most deprived population (females: 22.1 [21.3–22.7], males: 21.3 [20.4–22.0] years).

Conclusion This is the first study to investigate the associations between frailty-free life expectancies and socio-economic characteristics in Europe. Large inequalities in frailty-free and frail life expectancies exist between those with different socio-economic characteristics. This highlights the people most at risk of early frailty at younger ages and the geographic areas where the demand for health and social care among older people will be greatest as the population ages. This study uses data collected before the COVID-19 pandemic; it is unclear what effect the pandemic may have had on frailty-free life expectancies.