Characteristics of Patients with Chronic Obstructive Pulmonary Disease Exposed to Different Environmental Risk Factors: A Large Cross-Sectional Study

Jia-xi Duan,1,2 Wei Cheng,1,2 Yu-qin Zeng,1,2 Yan Chen,1,2 Shan Cai,1,2 Xin Li,3 Ying-qun Zhu,4 Ming Chen,5 Mei-ling Zhou,6 Li-bing Ma,7 Qi-mi Liu,8 Ping Chen1,2 1Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, People’s Republic of China; 2Research Unit of Respiratory Disease, Central South University, Changsha, Hunan 410011, People’s Republic of China; 3Division 4 of Occupational Diseases, Hunan Prevention and Treatment Institute for Occupational Diseases, Changsha, Hunan 410000, People’s Republic of China; 4Department of Respiratory Medicine, The Third Hospital of Changsha, Changsha, Hunan 410011, People’s Republic of China; 5Department of Respiratory Medicine, The No.1 Traditional Chinese Medicine Hospital in Changde, Changde, Hunan 415000, People’s Republic of China; 6Department of Respiratory Medicine, The First People’s Hospital of Huaihua, Huaihua, Hunan 418000, People’s Republic of China; 7Department of Respiratory Medicine, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541000, People’s Republic of China; 8Department of Respiratory and Critical Care Medicine, The Second People’s Hospital of Guilin, Guilin, Guangxi 541000, People’s Republic of ChinaCorrespondence: Ping ChenDepartment of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, 139 Renmin Middle Road, Changsha, Hunan 410011, People’s Republic of ChinaTel +86 731 8529 5248Email pingchen0731@csu.edu.cnPurpose: Tobacco smoking, biomass smoke, and occupational exposure are the main risk factors for chronic obstructive pulmonary disease (COPD). The present study analyzes data on exposure to these factors in a cohort of patients with COPD and assesses their differences in demographic and clinical characteristics.Patients and Methods: The cross-sectional observational study was conducted from November 2016 to December 2019. Inclusion criteria were patients aged over 40 years old with post-bronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) < 0.7. At baseline, demographic features and exposure history were recorded. Moreover, respiratory symptoms were assessed by the COPD Assessment Test (CAT) and modified Medical Research Council scale (mMRC). A generalized linear mixed model was used to adjust for potential confounders.Results: A total of 5183 patients with COPD were included in the final analysis. The results demonstrate that exposure to tobacco combined with other risk factors resulted in significantly higher CAT scores (16.0 ± 6.7 vs 15.3 ± 6.3, P = 0.003) and more severe dyspnea (patients with mMRC ≥ 2, 71.5% vs 61.6%, P < 0.001) than exposure to tobacco alone. In addition, COPD patients with biomass smoke exposure alone had higher CAT scores than patients with only tobacco or occupational exposure (17.5 ± 6.3 vs 15.3 ± 6.3, and 15.2 ± 6.3, respectively, P < 0.05 for each comparison) and were more likely to be female and older. In addition, COPD patients who suffered from occupational exposure developed more severe dyspnea than those exposed to tobacco alone (70.8% vs 61.6%, P < 0.05), as did those exposed to biomass smoke alone (74.2% vs 61.6%, P < 0.05). This difference remained strong even after adjustment for potential confounders.Conclusion: There are significant demographic and clinical differences among COPD patients with tobacco smoking, biomass smoke, and occupational exposures.Keywords: chronic obstructive pulmonary disease, tobacco, biomass smoke, occupational exposure