To investigate the development trajectory and influencing factors of frailty in elderly patients with chronic obstructive pulmonary disease (COPD).

A total of 429 elderly COPD patients admitted to our hospital from January 2024 to September 2025 were selected as the study subjects. The frailty screening scale (FSS) was used to assess frailty at admission (T0), 1 month (T1), 3 months (T2), and 6 months (T3) of follow-up. Latent class growth modeling (LCGM) was applied to identify frailty development trajectories, resulting in three groups: a stable group (C1, 205 cases), an increasing group (C2, 70 cases), and a decreasing group (C3, 154 cases). Univariate analysis and multivariate logistic regression were used to analyze the influencing factors of different trajectories.

At T0, 327 patients (76.22%) were frail, and at T3, 346 patients (80.65%) were frail. The correlation coefficients for frailty scores across T0, T1, T2, and T3 ranged from 0.553 to 0.685 (P<0.01). In the C1 group, the frailty score showed little change over the four time points, with an intercept of 2.68 and an average slope of 0.077. In the C2 group, the frailty score gradually increased over time, with an intercept of 0.97 and an average slope of 0.262. In the C3 group, the frailty score gradually decreased, with an intercept of 4.36 and an average slope of -0.257. Univariate analysis showed statistically significant differences in age, BMI, ethnicity, education level, disease duration, number of medication types, living alone, and grip strength among the different trajectory groups (P<0.05). Multivariate logistic regression showed that compared with the C1 group, BMI >24 (OR=6.957, 95%CI: 1.434~33.760, P=0.016), disease duration of 3~6 years (OR=0.335, 95%CI: 0.154~0.728, P=0.006), fear of progression (OR = 1.066, 95% CI: 1.014~1.121, P=0.012), and cognitive impairment (OR=1.068, 95% CI: 1.003~1.137, P=0.039) were factors associated with being in the C2 group. Compared with the C1 group, age ≥ 80 years (OR=2.277, 95%CI: 1.164~4.455, P=0.016), living alone (OR=6.031, 95%CI: 1.981~18.357, P=0.002), and grip strength (OR=1.051, 95%CI: 1.015~1.089, P=0.006) were factors associated with being in the C3 group. After 6 months of follow-up, 414 patients (96.50%) survived and 15 (3.50%) died, with a mortality rate of 8.57% in the C2 group, which was higher than that in the C1 group (2.44%) and the C3 group (2.60%).

The development of frailty in elderly COPD patients follows three distinct trajectories: stable, increasing, and decreasing. BMI, disease duration, fear of progression, cognitive impairment, living alone, grip strength, and age are influencing factors for different frailty trajectories. Dynamic monitoring of frailty trajectories may help identify high-risk individuals early and facilitate personalized interventions.