Abstract: Objective To investigate the clinical value of serum mast cell carboxypeptidase (MC-CP), C-C motif chemokine 26 (CCL26), and decoy receptor 3 (DcR3) in the diagnosis of obstructive sleep apnea syndrome (OSAS) in chronic obstructive pulmonary disease (COPD). Methods Ninety COPD patients who visited the First Affiliated Hospital of Hebei North University from January 2021 to January 2023 were collected. Among them, 48 patients with simple COPD were included in the COPD group, and 42 patients with COPD combined with OSAS were included in the COPD-OSAS group. During the same period, 48 healthy volunteers who underwent physical examination in that Hospital of Hebei North collected as the control group. Enzyme linked immunosorbent assay (ELISA) was applied to detect serum level of MC-CP, CCL26, and DcR3. Receiver operating characteristic (ROC) curve was applied to analyze the clinical value of serum level of MC-CP, CCL26, and DcR3 in the diagnosis of COPD complicated with OSAS. Multivariate Logistic regression was applied to analyze the influencing factors of COPD complicated with OSAS. Results Compared with the control group, the smoking index, C-reactive protein (CRP)and white blood cell count (WBC) in the COPD and COPD-OSAS groups increased obviously in sequence, the ratio of forced expiratory volume in first second to forced vital capacity (FEV1/FVC) decreased obviously in sequence (P＜0.05); Compared with the control group, the level of MC-CP, CCL26, and DcR3 in patients with COPD and COPD-OSAS increased significantly in sequence (P＜0.05); The combination of serum MC-CP, CCL26 and DcR3 had a higher area under the curve(AUC) for the diagnosis of COPD complicated with OSAS compared to the individual diagnosis (Z=4.066, P＜0.001; Z=2.391, P＜0.05; Z=2.353, P＜0.05). Multivariate Logistic regression analysis showed that smoking index, serum level of MC-CP, CCL26 and DcR3 were influencing factors for COPD complicated with OSAS (P＜0.05). Conclusions The simultaneously increased expression of MC-CP, CCL26 and DcR3 in the serum of COPD may support clinical diagnostic of COPD patients with OSAS.

Key words: mast cell carboxypeptidase, C-C motif chemokine 26, decoy receptor 3, chronic obstructive pulmonary disease, obstructive sleep apnea syndrome