Background: Chronic obstructive pulmonary disease (COPD) is associated with chronic inflammation, which persists at steady state and increases during acute exacerbation. Thus, establishment of biomarkers reflecting inflammation and disease status of COPD are needed. Oxidative stress is one of the key mechanisms of COPD, but its relevance is not fully elucidated.

Aims and objectives: We investigated the relationship between serum oxidative stress and COPD to determine its potential use as a biomarker of COPD severity.

Methods: We enrolled patients who visited hospital due to COPD from June 2020 to January 2023 and examined their characteristics and results of respiratory function tests and blood tests. Serum oxidative stress was evaluated by reactive oxygen metabolite (ROM) levels using the d-ROMs test (Diacron International, Grosetto, Italy).

Results: We recruited 104 patients in this study of whom 89 (85.6%) were men (median age, 76 years). Severity of airflow limitation was staged according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria as follows: stage 1, 33 patients; stage 2, 54 patients; stage 3, 14 patients; and stage 4, 3 patients. ROM levels were significantly higher in the severe air flow limitation group (GOLD 3,4) than non-severe group (GOLD 1,2). ROM levels correlated with CRP, SAA, and WBC (r=0.437, p<0.01; r=0.454, p<0.01; r=0.199, p<0.05, respectively) and with CAT score and SGRQ score (r=0.405, p<0.01; r=0.425, p<0.01, respectively). ROM levels correlated negatively with FEV1/FVC and %FEV1 (r= -0.245, p<0.05; r= -0.400, p<0.01, respectively).

Conclusions: Serum oxidative stress may be a biomarker for predicting the degree of chronic inflammation and severity of COPD.