Applicability of the electronic frailty index in younger and older adults in England: a population-based cohort study

The electronic frailty index (eFI) was developed in older adults (aged ≥65 years). There are currently no validated frailty scores in clinical practice for younger adults (aged 18-64 years). The aim of this study was to examine whether the eFI score in younger adults had similar or different associations with adverse health outcomes compared with older adults.

In this population-based cohort study, electronic health records from the UK Clinical Practice Research Datalink GOLD database were analysed. We used a cross-section of patients on Nov 30, 2015, who were alive and had been registered with a general practice for at least 2 years before data capture. Patients were stratified into younger adults (aged 18-64 years, n=708 235; 49·4% female) and older adults (aged 65-95 years, n=231 819; 54·3% female). For all included patients, eFI score, prevalence of individual eFI deficits, and eFI frailty category were calculated. For the main outcomes, crude and age-sex adjusted hazard ratios (HRs) were calculated for 1-year and 3-year mortality and emergency hospitalisation for each group compared with adults defined by the eFI as fit.

The prevalence of eFI-defined frailty was higher in older adults than younger adults. Specifically, in older adults, 77 290 (33·3%) of 231 819 had mild frailty, 44 523 (19·2%) had moderate frailty, and 22 572 (9·7%) had severe frailty. For younger adults, 76 991 (10·9%) of 708 235 had mild frailty, 12 552 (1·8%) had moderate frailty, and 2088 (0·3%) had severe frailty. Adjusted HRs for both 1-year mortality and 1-year emergency hospitalisation in younger adults with mild, moderate, and severe frailty were greater than in older adults with equivalent frailty categorisation. Specifically, compared with fit older adults, age-sex adjusted 1-year mortality HRs were 1·94 (95% CI 1·80-2·09) in older adults with mild frailty, 2·99 (2·77-3·22) with moderate frailty, and 4·03 (3·72-4·36) with severe frailty. Compared with fit younger adults, age-sex adjusted 1-year mortality HRs were 3·15 (2·80-3·55) in younger adults with mild frailty, 5·88 (4·95-6·98) with moderate frailty, and 12·61 (9·76-16·30) with severe frailty (Z score p<0·001 for all comparisons). Compared with fit older adults, age-sex adjusted HRs for 1-year emergency hospitalisation were 2·30 (2·22-2·39) in older adults with mild frailty, 4·09 (3·94-4·25) with moderate frailty, and 6·76 (6·50-7·03) with severe frailty. Compared with fit younger adults, age-sex adjusted HRs for 1-year emergency hospitalisation were 3·16 (3·07-3·25) in younger adults with mild frailty, 6·64 (6·34-6·94) with moderate frailty, and 13·02 (12·04-14·09) with severe frailty (Z score p<0·001 for all comparisons). Similar associations were observed for 3-year mortality and emergency hospitalisation.

Similarly to older adults, the eFI identifies younger adults with frailty at high risk of mortality and emergency hospital admission. The eFI might be a tool to identify individuals for further assessment and intervention.

Wellcome Trust and Chief Scientist Office.