Heterogeneous frailty trajectories and their differential impact on social integration in older adults with COPD: a prospective longitudinal study

Objective To explore the heterogeneous development trajectories of frailty in older adults with chronic obstructive pulmonary disease (COPD) and to examine the associations between different trajectory classes and levels of social integration at 12 months. Methods A prospective longitudinal study was conducted. Eligible older adults with COPD were consecutively recruited from the Sixth People’s Hospital of Nantong City between May 2024 and January 2025. Assessments were performed at five time points: baseline (T0), 3 months (T1), 6 months (T2), 9 months (T3), and 12 months (T4). Frailty was assessed using the Fried frailty phenotype. Social integration was evaluated across three dimensions: functional, structural, and subjective experience, using the Instrumental Activities of Daily Living scale, the 6-item Lubben Social Network Scale, and the UCLA Loneliness Scale (Version 3), respectively. Data analysis involved identifying potential frailty development trajectory classes using growth mixture modeling. Hierarchical multiple linear regression models were employed to examine the independent associations between different frailty trajectory classes and 12-month social integration outcomes, while controlling for baseline social integration levels, demographic, and clinical variables. Results A total of 347 patients completed all five follow-ups. Growth mixture modeling identified four distinct frailty development trajectories, in order of class proportion: Persistently Stable-Low Frailty (41.2%), Slow Progression (33.1%), Post-Exacerbation Fluctuation (18.5%), and Rapid Deterioration (7.2%). The four trajectory groups differed significantly in baseline characteristics such as age, lung function, and number of acute exacerbations in the past year (all p 0.05). At the 12-month follow-up, significant gradient differences were observed among the four groups in scores and change scores from baseline across all three social integration dimensions (all p 0.001), with the Rapid Deterioration group having the worst outcomes in all dimensions. Hierarchical multiple linear regression analysis showed that, after controlling for relevant confounding factors, the Rapid Deterioration trajectory was independently associated with worse instrumental activities of daily living, smaller social network size, and greater loneliness compared to the Persistently Stable-Low Frailty group (all p 0.05). The strength of these associations exhibited a gradient increase from the Slow Progression to the Rapid Deterioration trajectory. Conclusion Frailty development in older adults with COPD follows four heterogeneous trajectories, among which the Rapid Deterioration and Post-Exacerbation Fluctuation trajectories hold important clinical warning significance. Different frailty trajectory classes are independently associated with long-term social integration outcomes. In clinical practice, dynamically assessing frailty trajectories and stratifying patients based on risk has potential value for implementing targeted interventions to maintain their social functioning.