Xerostomia and hyposalivation in patients with obstructive sleep apnoea

Objective: (a) To report the xerostomia prevalence and severity in patients with obstructive sleep apnoea (OSA). (b) To assess the saliva pH in patients with OSA.

Design: Simultaneous cohort observational clinical study.

Setting: In Sleep Medicine Centre at Lomonosov Moscow State University from March to June 2019.

Participants: The study was conducted on 30 patients with OSA aged from 35 to 65 years.

Main outcomes measures: The diagnosis of sleep apnoea was made after standard polysomnography using the Domino programme. The severity of OSA was indicated using the Apnoea-Hypopnea Index. Xerostomia was evaluated using Fox's test. Hyposalivation was evaluated by measurement of salivary flow rate. Determination of the saliva pH was carried out with a pH metre. Statistical analysis was performed by one-way ANOVA and Tukey-Kramer multi-comparison test.

Results: Twenty-two out of 30 (73.3%) patients were diagnosed with "dry mouth". Hyposalivation was observed in 6 out of 30 (20%). Dry mouth on awakening was observed in 60.0%, 72.7% and 88.9% of patients with mild, moderate and severe OSA, respectively. The average salivary flow rate was 0.28 mL/min, 0.24 mL/min and 0.14 mL/min, respectively. The average pH value in patients with mild, moderate and severe apnoea was 6.40 ± 0.017, 6.15 ± 0.27 and 5.87 ± 0.24, respectively.

Conclusions: In patient with mild and moderate OSA, the saliva amount and rate are similar (P > .05). With the increase of OSA severity, both these parameters change (P < .001). The acidity of the saliva was correlated with the level of OSA, and it statistically increased with the increment of the OSA severity (P < .05-P < .001).