Differences in Clinical Characteristics of Patients with Chronic Obstructive Pulmonary Disease (COPD) in Osijek and Zadar and Possible Association with Global DNA Methylation as an Epigenetic Biomarker

Abstract

Environmental factors play an important role in the onset and development of chronic obstructive pulmonary disease (COPD). Previous studies have shown that global DNA methylation could be a useful biomarker in COPD. We hypothesized that COPD patients from two different Croatian regions might have clinical characteristics, quality of life, and global DNA methylation, which could be used as a possible epigenetic marker. The study included 136 COPD patients with an average age of 70 years, of whom about 70% were men. Among them, 37% were active smokers, 58% ex-smokers, and 5% non-smokers. There were 69 patients in Osijek and 67 in Zadar. The control group consisted of 64 subjects who were not diagnosed with COPD or other respiratory diseases, 32 from each center. We analyzed risk factors, severity and type of symptoms, exacerbations, comorbidities, and numerous parameters of lung function, phenotypic characteristics, quality of life, and global DNA methylation. We found that COPD patients in Zadar had more pronounced emphysema (P<0.001), while COPD patients from Osijek had more severe symptoms of cough and expectoration (P<0.001 for both ). Patients from Osijek had more cardiovascular comorbidities (P<0.001) and depression (P=0.01) than patients from Zadar. Analysis of global DNA methylation found that patients with COPD had lower values than the control group, but the difference was not statistically significant.

Keywords

• Epigenetics
• Global DNA methylation
• COPD
• Quality of life
• Lifestyle