Serum 8-OHdG as a Marker of Oxidative DNA Damage in Acute Exacerbations of COPD: Associations with GOLD Stage and Smoking Status-A Cross Sectional Study.

Background and Objectives: Oxidative stress is widely recognized as a key contributor to both the development and progression of chronic obstructive pulmonary disease (COPD), particularly during acute exacerbations (AECOPD). 8-Hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, has been insufficiently investigated as a systemic biomarker in this setting. This study evaluated the relationship between serum 8-OHdG levels, airflow limitation severity, and smoking status in patients hospitalized with AECOPD. Materials and Methods: We conducted a cross-sectional study including 176 patients admitted for AECOPD and stratified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages. The study population comprised patients with comparable distributions of age, sex, smoking status, diabetes, cardiovascular comorbidities, and area of residence across GOLD categories. Serum 8-OHdG, leukocyte count, neutrophil percentage, C-reactive protein (CRP), fibrinogen, and procalcitonin were measured. Group comparisons, multivariable logistic regression analyses, and smoking-status subgroup analyses were performed. Results: Serum 8-OHdG levels increased significantly with advancing airflow limitation severity (p = 0.038), with higher concentrations observed in patients with GOLD 4 disease compared to GOLD 1-2 disease (p = 0.023). In multivariable analysis, 8-OHdG was the only biomarker independently associated with GOLD stage (OR = 2.44, 95% CI: 1.12-5.31, p = 0.025). Higher serum 8-OHdG levels were also independently associated with smoking status (OR = 1.20, 95% CI: 1.05-1.37, p = 0.022). Ever-smokers demonstrated significantly higher 8-OHdG concentrations than never-smokers in GOLD 1-2 and GOLD 3 disease, whereas procalcitonin levels were higher among never-smokers with advanced COPD. Conclusions: Serum 8-OHdG levels measured during AECOPD are associated with both airflow limitation severity and smoking status. These findings support the potential role of oxidative DNA damage as a clinically relevant component of COPD pathophysiology and suggest that serum 8-OHdG may represent a useful biomarker for disease characterization in patients experiencing acute exacerbations.