Prevalence and future estimates of frailty and pre-frailty in a population-based sample of people 70 years and older in Norway: the HUNT study

Background Frailty in older people is a rising global health concern; therefore, monitoring prevalence estimates and presenting projections of future frailty are important for healthcare planning. Aim To present current prevalence estimates of frailty and pre-frailty and future projections according to both dominant frailty models in a large population-based observational study including adults ≥ 70 years in Norway. Methods In this population-based observational study, we included 9956 participants from the HUNT4 70 + study, conducting assessments at field stations, homes, and nursing homes. Frailty was assessed using Fried criteria and a 35-item frailty index (HUNT4-FI). Inverse probability weighting and calibration using post-stratification weights and aggregated register data for Norway according to age, sex, and education ensured representativeness, and population projection models were used to estimate future prevalence. Results According to Fried criteria, the current prevalence rates of frailty and pre-frailty in people ≥ 70 years were 10.6% and 41.9%, respectively, and for HUNT4-FI 35.8% and 33.2%, respectively. Compared to previous European estimates we identified higher overall frailty prevalence, but lower prevalence in younger age groups. Projections suggest the number of Norwegian older adults living with frailty will close to double by 2040. Conclusion Frailty in older people in Norway is more prevalent than previous European estimates, emphasising the imperative for effective interventions aimed to delay and postpone frailty and ensure healthcare system sustainability in an ageing population. Future planning should consider the great heterogeneity in health and functioning within the 70 + population. Supplementary Information The online version contains supplementary material available at 10.1007/s40520-024-02839-y.

Supplementary method -construction of HUNT4-FI FI is based on a comprehensive geriatric assessment that maps several deficits or conditions across organ systems that accumulate with ageing and are related to health and function [3].HUNT4-FI was constructed in accordance with updated recommendations for creating a FI from an existing dataset [4].
Each item was given a score between 0 and 1 with 0 representing that the deficit was absent.If a deficit was present, most items were scored 1.For some ordinal or interval data we used the scores 0, 0.5 and 1.0 for three response levels, and 0, 0.25, 0.5, 0.75 and 1.0 for five response levels, in accordance with previous studies [4,5].Answers "good" or "excellent".

Supplementary
Answers "poor" or "not so good".

Table 1
Descriptive characteristics of participants in total sample (N=9956) included in frailty analyses versus participants excluded from analyses Continuous variables are expressed as mean (SD), categorical variables as N (%).MoCA= Montreal Cognitive Assessment.P-values for within-group differences for Body Mass Index: Fried Criteria (p=0.253) and HUNT4-FI (p=0.239).For all other variables p=<0.001regardless of frailty measurement.Supplementary Table 2 Number of participants (N) for each variable included in descriptive analyses (

Table 4
HUNT4-FI variables with coding