To investigate the predictive value of inflammatory composite indicators for the risk of atrial fibrillation in patients with chronic obstructive pulmonary disease (COPD).

A total of 860 patients with COPD admitted to Jiangyin People′s Hospital and Nanjing Chest Hospital from January 2019 to December 2024 were enrolled and randomly divided into a training set 600 cases and a validation set 260 cases at a 7︰3 ratio. In the training set, patients were categorized into an AF group 128 cases and a non atrial fibrillation group 472 cases according to the presence of atrial fibrillation. The neutrophiltolymphocyte ratio (NLR), platelettolymphocyte ratio (PLR), monocytetohighdensity lipoprotein cholesterol ratio (MHR), and Creactive proteintoalbumin ratio (CAR) were compared between the two groups. Lasso regression was used to select predictive variables for constructing a nomogram. The discriminative ability was assessed by receiver operating characteristic (ROC) curves, calibration was evaluated by the HosmerLemeshow test, and clinical net benefit was determined by decision curve analysis (DCA).

In the training set, the atrial fibrillation group had significantly higher NLR, PLR, MHR, and CAR than the non atrial fibrillation group [(2.18±0.42) vs. (1.58±0.39), (142.07±42.13) vs. (112.81±26.69), (0.42±0.12) vs. (0.34±0.10), (1.28±0.24) vs. (0.76±0.20), all P<0.001]. Lasso regression identified the four variables (NLR, PLR, MHR, CAR) for nomogram construction, with corresponding points of 12.11, 14.51, 6.58, and 44.44, respectively. In the validation set, ROC analysis showed an AUC of 0.902 (95%CI: 0.852~0.952), with a sensitivity of 83.70% and specificity of 82.10%. The calibration curve had a Cindex of 0.909, and the HosmerLemeshow test gave χ²=7.0874, df=8, P=0.5272. DCA demonstrated that the model′s net benefit remained stable above 0.4 across threshold probabilities of 0~0.8, indicating high clinical utility.

The nomogram based on NLR, PLR, MHR, and CAR shows good discriminative ability, satisfactory calibration, and significant clinical net benefit for predicting atrial fibrillation in COPD patients, providing a useful tool for early identification of highrisk individuals in clinical practice.