Objective: To assess the clinical utility of serum and saliva myeloperoxidase (MPO) and serum C-reactive protein (CRP) levels as markers of inflammation in obstructive sleep apnea (OSA).
Design: Prospective, controlled, observational study.
Setting: Snoring and respiratory sleep disorders centre at a tertiary hospital.
Methods: This study included 32 OSA-diagnosed patients and 24 age- and gender-matched healthy subjects following endoscopic airway evaluation and polysomnography.
Main outcome measures: Saliva and serum MPO levels were analyzed by flow cytometry. Serum CRP levels were determined using a latex assay. The different groups were compared through parametric tests. Linear and logistic regression models using The Apnea-Hypopnea Index (AHI) as a dependent variable assessed the association of independent variables, including saliva and serum MPO levels, serum CRP levels, age, and body mass index (BMI).
Results: Salivary MPO and serum CRP levels were significantly higher in the OSA group compared to controls (p < .0001, p = .0001). A moderate positive correlation was detected between saliva MPO and AHI, the oxygen desaturation index, and sleep efficiency (p = .0001, p = .0001, and p = .0002, respectively) by excluding potential confounding factors (age and BMI). Salivary MPO and BMI levels were associated with AHI in a linear regression model (p < .0001) and found to be concordant variables with the presence of OSA.
Conclusion: Increased salivary MPO levels in OSA subjects in this study support previously defined persistent local inflammation in these patients. Therefore, salivary MPO levels may be useful as oropharyngeal inflammatory markers in OSA patients.