To investigate the relationship between the frailty index (FI) and acute exacerbations in elderly patients with chronic obstructive pulmonary disease (COPD).

A total of 87 elderly patients with acute exacerbation of COPD (AECOPD) admitted to our hospital between January 2020 and January 2025 were selected. Patients were divided into an observation group (frail, FI ≥ 0.25, n=46) and a control group (non-frail, FI<0.25, n=41). General data of the two groups were compared. Multivariate logistic regression was used to analyze influencing factors for frailty in AECOPD patients. Pearson correlation analysis was used to examine the relationship between FI and lung function indicators. The receiver operating characteristic (ROC) curve was used to analyze the value of indicators in predicting the severity of AECOPD in elderly patients. The prognosis of the two groups was compared after a 1-year follow-up.

The observation group had significantly higher COPD duration, (neutrophil+ monocyte)/lymphocyte ratio(NMLR), number of hospitalizations, C-reactive protein(CRP) levels, and FI than the control group (P<0.05). Multivariate logistic regression analysis showed that the annual number of hospitalizations and NMLR were risk factors for frailty in AECOPD patients (P<0.05). Levels of forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and FEV₁/FVC in the observation group were lower than those in the control group (P<0.05). Pearson correlation analysis showed that FI was negatively correlated with FEV₁, FVC, and FEV₁/FVC (r=-0.577, -0.582, -0.539, respectively, P<0.001). The number of hospitalizations (r=-0.414, -0.481, -0.510) and NMLR (r=-0.451, -0.504, -0.504) were negatively correlated with lung function indicators (P<0.05). FI demonstrated high sensitivity and specificity for predicting AECOPD severity, with an AUC of 0.935, which was higher than the AUC for the number of hospitalizations (AUC=0.621) and NMLR (AUC=0.708) (Z hospitalization-FI=5.389, Z NMLR-FI=3.983, P<0.05). During the follow-up of elderly AECOPD patients, 61 survivors (70.11%) and 26 deaths (29.89%) were recorded. In the observation group, there were 28 survivors (60.87%) and 18 deaths (39.17%); in the control group, there were 33 survivors (80.49%) and 8 deaths (19.51%). The mortality rate in the observation group was significantly higher than that in the control group (P<0.05).

FI is an important factor influencing the severity of AECOPD in elderly patients, closely related to lung function. Frailty is associated with an increased risk of death in AECOPD patients. FI may serve as a potential indicator for assisting in predicting the severity and prognosis of AECOPD, providing a reference for clinical practice.