C109-09 Oxidative Stress Index and Inflammatory Biomarkers as Indicators of Disease Severity in Obstructive Sleep Apnea

Abstract Rationale Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder characterized by recurrent upper airway obstruction, resulting in intermittent hypoxia and sleep fragmentation. These pathophysiological processes promote oxidative stress and systemic inflammation, which are key contributors to the cardiovascular and metabolic complications observed in OSA. However, the association between disease severity and specific circulating oxidative and inflammatory biomarkers remains incompletely defined. In this study, we aimed to evaluate the oxidative stress index (OSI) together with superoxide dismutase (SOD), malondialdehyde (MDA), and tumor necrosis factor-α (TNF-α) to better characterize the biological burden of OSA and to identify clinically relevant markers of disease severity. Methods This case-control study included 65 adults who had undergone overnight polysomnography within the preceding three years and met predefined inclusion criteria. Participants had no known comorbidities, a smoking history of 10 pack-years, no history of major surgery, and a body mass index 30 kg/m². Based on the apnea-hypopnea index (AHI, events/hour), subjects were classified as control (AHI 5), mild OSA (AHI 5-14.9), moderate OSA (AHI 15-29.9), or severe OSA (AHI ≥30). Eligible participants were recalled to the outpatient clinic for clinical reassessment, during which fasting venous blood samples were obtained. Serum total oxidant capacity (TOC), total antioxidant capacity (TAC), oxidative stress index (OSI), malondialdehyde (MDA), superoxide dismutase 1 and 2 (SOD1, SOD2), and tumor necrosis factor-α (TNF-α) levels were measured using commercially available assay kits. Group comparisons were performed using the Kruskal-Wallis test, and correlations were assessed using Spearman’s rank analysis. A p value 0.05 was considered statistically significant. Results Significant differences were observed among groups in oxidative and inflammatory markers. TOC and OSI showed an overall increasing trend with OSA severity (p = 0.0298 and p = 0.0034), whereas TAC and SOD2 levels decreased significantly (p = 0.005 and p = 0.0032). MDA and TNF-α levels were significantly higher in moderate and severe OSA compared with controls (p = 0.0145 and p = 0.0051), while SOD1 did not differ among groups (p = 0.0532). AHI correlated positively with OSI, TOC, MDA, and TNF-α and negatively with TAC and SOD2 (all p 0.05). Indices reflecting hypoxic burden were positively associated with OSI and TNF-α and inversely associated with SOD2 (all p 0.01). Conclusion Increasing OSA severity is associated with greater oxidative stress and systemic inflammation. OSI and related biomarkers (SOD, MDA, and TNF-α) may serve as practical indicators of biological disease burden and hypoxic injury in OSA. This abstract is funded by: Kütahya Health Sciences University, Scientific Research Projects Unit (BAP)