Frailty transitions and prevalence in an ageing population: longitudinal analysis of primary care data from an open cohort of adults aged 50 and over in England, 2006-2017

Abstract

Introduction: frailty is common in older adults and is associated with increased health and social care use. Longitudinal information is needed on population-level incidence, prevalence and frailty progression to plan services to meet future population needs.

Methods: retrospective open cohort study using electronic health records of adults aged ≥50 from primary care in England, 2006-2017. Frailty was calculated annually using the electronic Frailty Index (eFI). Multistate models estimated transition rates between each frailty category, adjusting for sociodemographic characteristics. Prevalence overall for each eFI category (fit, mild, moderate and severe) was calculated.

Results: the cohort included 2,171,497 patients and 15,514,734 person-years. Frailty prevalence increased from 26.5 (2006) to 38.9% (2017). The average age of frailty onset was 69; however, 10.8% of people aged 50-64 were already frail in 2006. Estimated transitions from fit to any level of frailty were 48/1,000 person-years aged 50-64, 130/1,000 person-years aged 65-74, 214/1,000 person-years aged 75-84 and 380/1,000 person-years aged ≥ 85. Transitions were independently associated with older age, higher deprivation, female sex, Asian ethnicity and urban dwelling. Mean time spent in each frailty category decreased with age, with the longest period spent in severe frailty at all ages.

Conclusions: frailty is prevalent in adults aged ≥50 and time spent in successive frailty states is longer as frailty progresses, resulting in extended healthcare burden. Larger population numbers and fewer transitions in adults aged 50-64 present an opportunity for earlier identification and intervention. A large increase in frailty over 12 years highlights the urgency of informed service planning in ageing populations.

Keywords: ageing population; frailty; incidence; older people; prevalence; transitions.

Figure 1

Proportion transitioning into different frailty categories (states), by starting frailty categories and age groups (fully adjusted model). Cohort age structure changed slightly over time, with 524,936 (47.5%) aged ≥65 in 2006 and 735,936 (49.4%) in 2017, for age 85+ this was 68,332 (6.2%) and 102,949 (6.9%), respectively. Over the same period, overall prevalence of frailty increased from 26.5 (95% CI 26.4–26.6) to 38.9% (95% CI 38.8–39.0). Frailty was already present in the 50–64 group, rising from 10.8% in 2006 to 19.6% in 2017 and prevalence increased with age (Appendix 3). Prevalence increased in all frailty categories, with the greatest proportion seen in mild and moderate frailty in all age groups (Figure 2). Total numbers with frailty increased from 292,751 to 579,828, with the greatest increase in numbers seen in the 65–74 age group and mild frailty category.

Figure 2

Prevalence of frailty categories 2006–2017 by age group.