Plasma 4-hydroxynonenal estimates severity and prognosis in patients with acute exacerbation of chronic obstructive pulmonary disease.

4-Hydroxynonenal (4-HNE), a product of lipid peroxidation, is recognized as a biomarker of oxidative stress. However, its relationship with the severity and prognosis of acute exacerbation in chronic obstructive pulmonary disease (AECOPD) remains unclear. This prospective cohort study aimed to investigate the associations between plasma 4-HNE levels and disease severity and prognosis in AECOPD patients. A total of 150 AECOPD patients, 80 stable COPD (SCOPD) patients, and healthy volunteers were enrolled. Plasma 4-HNE and inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). Compared to healthy individuals, plasma 4-HNE levels were significantly elevated in both SCOPD and AECOPD patients, with progressively increasing alongside worsening pulmonary function and higher mMRC, CAT, and CCQ scores. In AECOPD patients, plasma 4-HNE was positively correlated with inflammatory cytokines, and linear regression analysis revealed that elevated plasma 4-HNE was associated with increased disease severity. Furthermore, higher plasma 4-HNE levels at admission were linked to prolonging hospital stays and AECOPD, indicating a poorer prognosis. Compared with several conventional biomarkers, plasma 4-HNE demonstrated superior predictive value for AECOPD and clinical outcomes. These findings suggest that plasma 4-HNE may be a useful biomarker for assessing severity and prognosis in AECOPD patients, potentially playing a role in the underlying pathophysiology of the disease.