Towards Healthy Ageing: Using the Concept of Intrinsic Capacity in Frailty Prevention

Objectives: To examine whether intrinsic capacity (IC) could predict frailty, whether declines in specific domains of IC could lead to frailty, and whether different combinations of domains could represent different risks of developing frailty.

Setting: Community.

Participants: Chinese people aged 65 years and older.

Measurements: Using data from a prospective cohort study, we derived a summary score for IC and scores for the five domains (cognitive, locomotor, vitality, sensory, psychological) for each participant at baseline. Frailty was assessed according to the Fried's frailty phenotype at baseline, 2- and 4-year follow-ups. Participants were classified as frail if they had ≥3 of the following criteria: weight loss, self-rated exhaustion, weakness, slow walking speed, and low physical activity.

Results: Four thousand participants were interviewed at baseline. Overall mean age was 72.5 years; 50% were women. Between baseline and the 2-year follow-up, 5.7% of non-frail participants developed frailty; between 2- and 4-year follow-ups, 5.7% of non-frail participants developed frailty. The average annual incidence rate of frailty was 2.9%. Higher scores on IC at baseline were associated with a lower risk of incident frailty at both follow-ups (year 2, odds ratio (OR)=0.64, 95% confidence interval (CI)=0.59-0.71); year 4, OR=0.64, 95%CI=0.58-0.71) after adjustment for age, sex, educational level, and chronic diseases. Across the five domains, vitality was the strongest predictor of incident frailty at each follow-up (year 2, OR=0.33, 95%CI=0.24-0.45; year 4, OR=0.33, 95%CI=0.23-0.46). Compared to other combinations of any two domains, having 'high' scores on both vitality and locomotor domains was associated with the lowest risk of incident frailty (year 2, OR=0.11, 95%CI=0.06-0.22, area under the curve (AUC)=0.770; year 4, OR=0.18, 95%CI=0.10-0.32, AUC=0.782).

Conclusion: This study provides evidence that IC was independently associated with incident frailty. It also finds that vitality was the domain most strongly associated with incident frailty. Finally, it suggests that optimizing multiple domains of IC, particularly vitality and locomotor, may prevent frailty.