The Association of Salivary Biomarkers With the Severity of Obstructive Sleep Apnea and Concomitant Hypertension

Background: We aimed to assess the association between salivary alpha-amylase and salivary cortisol, and obstructive sleep apnea (OSA) severity. Methods: Fifty-eight adults with suspected OSA were divided into the following 4 groups based on the apnea hypopnea index (AHI): control (AHI <5 events/hour), mild OSA (5 events/hour <= 15 events/hour), moderate OSA (15 events/hour <= 30 events/hour) and severe OSA (AHI >30 events/hour) groups. Salivary samples were collected after overnight polysomnography. Correlations between the salivary biomarkers and polysomnography parameters were analyzed. Results: Salivary alpha-amylase levels of the moderate and severe OSA groups were significantly higher than those of the control and mild OSA groups, and no association was found between salivary cortisol and OSA severity. The salivary alphaamylase levels were positively correlated with the AHI (r = 0.538; P < 0.01) and microarousal index (r = 0.541, P < 0.01), and negatively correlated with the lowest pulse oxygen saturation (r = -0.375, P < 0.01). Salivary cortisol levels were significantly higher in patients with hypertension than in those without hypertension (10.01 +/- 2.77 ng/mL vs. 5.52 +/- 1.90 ng/mL, P < 0.05), and the salivary alpha-amylase levels were highest in the OSA concomitant hypertension group (32.81 +/- 11.85 U/mL). Areas under the receiver operator characteristic analysis revealed that the cutoff values of salivary alpha-amylase for identifying moderate-severe OSA and OSA concomitant hypertension were 17.64 U/mL (sensitivity 85%, specificity 91%) and 25.35 U/mL (sensitivity 70%, specificity 94%), respectively. Conclusions: Salivary alpha-amylase is positively associated with the severity of OSA and OSA concomitant hypertension.