Intrinsic capacity transitions as predictors of frailty transitions in community-dwelling older adults: Findings from the Korean Frailty and Aging Cohort Study

Background: Frailty is associated with reduced intrinsic capacity (IC). However, studies evaluating longitudinal transitions between IC and frailty are limited. We conducted longitudinal analyses to investigate the association between intrinsic capacity (IC) and frailty transitions among community-dwelling older adults in Korea. Methods: A total of 2,345 older adults who completed baseline and two-year follow-up surveys were selected from the Korean Frailty and Aging Cohort Study. IC was measured in five domains: locomotion, vitality, cognition, psychology, and sensory function. Frailty was defined using the Fried frailty phenotype. Transitions in IC and frailty were assessed. Logistic regression analysis was used to analyze the association between baseline IC, IC transitions, and frailty transitions. Results: During the two-year follow-up, 17.8 % of participants improved, 20.4 % worsened, and 61.8 % maintained the same frailty status. Low IC (odds ratio [OR]=1.93; 95 % confidence interval [CI]=1.42–2.61) significantly predicted remaining frail or worsening frailty. Worsened IC increased the risk of remaining frail or worsening frailty, whereas improved IC decreased this risk. Among the IC domains, the onset of new locomotion (OR=3.33; 95 % CI=2.39–4.64), vitality (OR=2.12; 95 % CI=1.55–2.91), and psychological (OR=3.61; 95 % CI=2.64–4.92) impairment predicted remaining frail or worsening frailty. Conclusions: Low and worsened IC were associated with an increased risk of remaining frail or worsening frailty over two years. These findings indicate that changes in IC can predict frailty transitions, thereby emphasizing the importance of enhancing IC in preventing frailty progression.