Biomarkers in patients with suspected obstructive sleep apnea and obstructive lung disease: Associations among polysomnographic, demographic and spirometric parameters

PURPOSE: The purpose of this study was to characterize the associations between inflammatory and oxidative stress biomarkers, demographic, polysomnographic and spirometric parameters in patients with suspected obstructive sleep apnea (OSA) and/or obstructive airway disease.METHODS: This was a cross-sectional exploratory study of patients referred to the University of British Columbia Sleep Clinic who had a diagnostic polysomnogram for suspected OSA. All patients had samples collected for measurements of IL-10, IL-6, e-selectin, endostatin, VCAM-1, ICAM-1, PDGF, thrombospondin-2, 8-OHdG, 8-isoprostane and superoxide dismutase. Spearman correlation and multiple linear regression were used to identify predictors of biomarkers.RESULTS: A total of 63 patients were included: 65% male, mean age 53 years and body mass index (BMI) 33 kg/m(2). Inflammatory biomarkers were associated with female sex (IL-6, coefficient 0.51, p = 0.032), FEV1 (IL-6, coefficient -0.02, p = 0.013) and BMI (VCAM-1, coefficient 0.009, p = 0.051). The oxidative stress marker, 8-OHdG, was associated with hypoxemia in rapid eye movement (REM) sleep (coefficient 0.006, p = 0.02). Age and BMI were both independently associated with percentage of time spent below SpO(2) 90%. REM sleep and patients with overlap conditions and OSA had greater degree of REM and nonrapid eye movement (NREM) sleep hypoxemia than control group. Lastly, there were no differences in oxidative or inflammatory biomarkers between control, OSA, obstructive airway disease and overlap groups though the number of patients in each group were small.CONCLUSION: Female sex, lower FEV1 and increased BMI were independent predictors of increased inflammatory biomarker levels. The oxidative stress marker 8-OHdG was associated with hypoxemia indices of REM. Larger studies are warranted to delineate biomarker profiles in patients with overlap conditions.