Trajectory of intrinsic capacity and association with daily life ability in people aged 50 years and over in Shanghai

Objective: To identify the change trajectory of intrinsic capacity in people aged ≥50 years in Shanghai and explore the impact of intrinsic capacity trajectory change on overall function and dalily life activities in this population. Methods: The longitudinal data from round 1 to 3 Study of Global Ageing and Adult Health in Shanghai were used. The total intrinsic ability scores from five dimensions of cognition, psychology, sensory, vitality and locomotion were calculated. The censored normal model of group-based trajectory was used to identify the trajectory of intrinsic capacity change over time. Linear regression model and multivariate logistic regression model were used to analyse the effects of different levels intrinsic capacity trajectory on the scores of the WHO Disability Assessment Schedule (WHODAS), the activity of daily living (ADL) and the instrumental activities of daily living (IADL). Results: A total of 2 302 study participants aged ≥50 years with 3 round complete data were included in this study, and 3 levels of intrinsic capacity trajectory were identified, low-level trajectory (9.3%), medium-level trajectory (41.7%), and high-level trajectory (49.0%). Compared with the high-level group, the medium-level and low-level groups had higher WHODAS scores, which increased by 3.578 (95%CI: 2.028-5.129) and 12.620 (95%CI: 9.951-15.289), respectively, and those with more severe disability and those in the low-level group were at higher risk for severe difficulty in ADLs (OR=12.450, 95%CI: 4.310-35.966) and IADLs (OR=5.479, 95%CI: 1.311-22.904). Conclusions: Heterogeneity in trajectory of intrinsic capacity exists in people aged ≥50 years in Shanghai. Middle-aged and elderly people with low initial level and rapid decline trajectory of intrinsic capacity are at greater risk for the decline of daily life ability and the increase of disability. It is necessary to strengthen the long-term dynamic monitoring and evaluation of the change trajectory of intrinsic capacity in this population.