Analysis in related factors of cognitive impairment in patients with overlap syndrome of chronic obstructive pulmonary disease complicated with obstructive sleep apnea hypopnea syndrome

Objective  To investigate the relationships of cognitive impairment (CI) with levels of endothelin-1 (ET-1) and neutrophil gelatinase-associated lipocalin (NGAL) in patients with overlap syndrome of chronic obstructive pulmonary disease complicated with obstructive sleep apnea hypopnea syndrome (COPD-OSAHS).

Methods  A total of 87 patients with overlap syndrome of COPD-OSAHS in the Zhangjiakou City First Hospital of Hebei Province from January 2021 to January 2022 were selected as COPD-OSAHS group, and these patients were divided into CI group with 41 cases and non-CI group with 46 cases according to the condition of CI; another 62 COPD patients were selected as COPD group. Serum ET-1 and NGAL levels were detected by enzyme-linked immunosorbent assay. Scores of the Montreal Cognitive Assessment (MoCA) and the levels of serum ET-1 and NGAL were compared between COPD-OSAHS group and COPD group. Pearson correlation coefficient was used to analyze the correlations of the MoCA score with serum ET-1 and NGAL levels in patients with overlap syndrome of COPD-OSAHS; the multivariate Logistic regression model was used to analyze the influencing factors of CI in patients with overlap syndrome of COPD-OSAHS; the receiver operating characteristic (ROC) curve was used to analyze the predictive value of serum ET-1 and NGAL levels for CI in patients with overlap syndrome of COPD-OSAHS.

Results  The score of each item in MoCA and total score in the COPD-OSAHS group were significantly lower than those in the COPD group (P < 0.01). The levels of serum ET-1 and NGAL in the COPD-OSAHS group were (52.81±9.95) pg/mL and (7.63±1.62) ng/mL respectively, which were significantly higher than (27.84±6.98) pg/mL and (3.13±1.19) ng/mL in the COPD group (P < 0.01). Pearson correlation coefficient showed that the levels of serum ET-1 and NGAL in patients with overlap syndrome of COPD-OSAHS were negatively correlated with the MoCA score (r=-0.622, -0.613, P < 0.001). Compared with the patients in the non-CI group, the patients in the CI group were older, the ratios of patients with body mass index (BMI) ≥ 28 kg/m², smoking, COPD duration ≥ 5 years, severe COPD, OSAHS duration≥ 5 years, and severe OSAHS were significantly higher, and the levels of ET-1 and NGAL were significantly higher in the CI group (P < 0.05). Multivariate Logistic regression model analysis showed that age, BMI≥ 28 kg/m², severe COPD, OSAHS duration≥ 5 years, severe OSAHS, ET-1 and NGAL were the independent risk factors for CI in patients with overlap syndrome of COPD-OSAHS (P < 0.05). ROC curve showed that the area under curve (AUC) of CI predicted by serum ET-1 and NGAL in patients with overlap syndrome of COPD-OSAHS was significantly greater than that predicted by one indicator alone (Z=2.039, 2.347, P=0.041, 0.019).

Conclusion  Patients with overlap syndrome of COPD-OSAHS have obvious CI, the increased levels of serum ET-1 and NGAL are closely associated with CI, which is also helpful for CI prediction.