[Association of plasma roundabout 4 concentration with pulmonary ventilation function decline in COPD patients]

Objective: To investigate the association of plasma roundabout 4 concentration with pulmonary ventilation function decline in chronic obstructive pulmonary disease (COPD) patients. Methods: To get the effective data, the study was conducted in the outpatient department of West China Hospital from September 2017 to September 2018. The subjects meeting the inclusion and exclusion criteria were continuously included. Among them, the COPD group (75 cases) was from the respiratory outpatient department, and the healthy control group (57 cases) was from the health examination center at the same time. Data of basic demographic characteristics, clinical characteristics, pulmonary ventilation function parameters and blood samples were collected. The concentrations of roundabout 4, C reactive protein (CRP), interleukin (IL)-6, IL-8, IL-1b and tumor necrosis factor (TNF)-α in plasma were detected, and the differences among groups were compared, the correlation between plasma roundabout 4 and pulmonary ventilation function parameters and inflammatory factors was analyzed. The diagnostic efficiency of roundabout 4 to COPD was analyzed according to receiver operating characteristic (ROC) curve. Results: The plasma concentration of roundabout 4 in COPD group was significantly higher than that in healthy control group [(41.3±14.2) vs (27.7±13.3) ng/L; P<0.001], the sensitivity and specificity of roundabout 4 in the diagnosis of COPD were 0.827 and 0.702 respectively. Correlation analysis showed that the plasma concentration of roundabout 4 was negatively correlated with lung function parameters forced expiratory volume in one second/forced vital capacity (FEV(1)/FVC), the first second forced expiratory volume as a percentage of the estimated value (FEV(1)%pred), forced exhalation of 50% and 25% lung capacity (MEF50, MEF25) and maximal mid-expiratory flow (MMEF) (r=-0.399, -0.321, -0.439, -0.363, -0.458; all P<0.001), positively correlated with CRP (adjusted r=0.311, P<0.001). Conclusion: The increased concentration of roundabout 4 in plasma leads to the decline of pulmonary ventilation function in COPD patients.