To investigate the relationship between the D-dimer to albumin ratio (DAR), chest computed tomography (CT) parameters, and pulmonary function in acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

A retrospective analysis was conducted on 83 patients with AECOPD (observation group) and 82 patients with COPD (control group) admitted to our hospital from March 2019 to December 2024. Pulmonary function, DAR, and CT parameters were compared between the two groups. Spearman′s rank correlation analysis was used to evaluate the relationships among DAR, chest CT parameters, and pulmonary function.

The DAR in the observation group was significantly higher than that in the control group [17.90 (12.17, 38.93) vs. 8.39 (6.27, 13.73), P<0.001]. The area under the receiver operating characteristic (ROC) curve (AUC) for DAR in diagnosing AECOPD was 0.827, which was higher than that of C-reactive protein (AUC 0.803), neutrophil count (AUC 0.647), lymphocyte count (AUC 0.639), and monocyte count (AUC 0.637). The lung volume in the observation group was significantly lower than that in the control group [(3.58±0.93)L vs. (4.77±1.14)L, t=7.351, P<0.001], while the emphysema index (EI) [19.36(10.62, 30.46)% vs. 6.03(3.83, 12.08)%, Z=-6.965, P<0.001] and air trapping index (ATI) [0.97±0.02 vs. 0.91±0.02, t=19.270, P<0.001] were significantly higher. The forced expiratory volume in one second (FEV₁) [53.00 (42.00, 69.00)% vs. 62.50 (50.00, 74.00)%, Z=-2.259, P=0.024], FEV₁/forced vital capacity (FVC) [58.22 (51.87, 65.48)% vs. 63.71 (55.23, 68.77)%, Z=-2.720, P=0.007], maximum mid-expiratory flow (MMEF) [25.00 (15.25, 34.50)% vs. 29.55 (21.05, 41.00)%, Z=-2.030, P=0.042], and carbon monoxide diffusing capacity (DL_CO) [63.00 (45.50, 77.50)% vs. 75.00 (55.25, 89.00)%, Z=-3.222, P=0.001] were significantly lower in the observation group compared to the control group (P<0.05). Spearman′s rank correlation and multiple linear regression analyses showed that DAR was negatively correlated with FEV₁ (Rho=-0.287, P<0.001), FEV₁/FVC (Rho=-0.264, P<0.001), and MMEF (Rho=-0.267, P<0.001). Lung volume was positively correlated with FEV₁(Rho=0.336, P<0.001), FEV₁/FVC (Rho=0.281, P<0.001), MMEF (Rho=0.215, P=0.001), and DL_CO (Rho=0.195, P=0.011). ATI was negatively correlated with FEV₁ (Rho=-0.311, P<0.001), FEV₁/FVC (Rho=-0.309, P<0.001), MMEF (Rho=-0.286, P<0.001), and DL_CO (Rho=-0.299, P<0.001). EI was negatively correlated with FEV₁ (Rho=-0.281, P<0.001), FEV₁/FVC (Rho=-0.289, P<0.001), and DL_CO (Rho=-0.162, P=0.038). The AUC of DAR for predicting readmission or death in AECOPD was 0.783 (95%CI: 0.575~0.992), with an optimal cutoff value of 16.448. Kaplan-Meier survival curve analysis showed that the event-free survival rate of AECOPD patients with DAR<16.448 (n=18) was significantly higher than that of patients with DAR ≥16.448(n=19) (88.89% vs. 47.37%, χ²=6.973, P=0.008).

DAR, lung volume, EI, and ATI in AECOPD patients are correlated with pulmonary function parameters.