The role of dry mouth in screening sleep apnea.

Purpose Of The Study: Effective screening questionnaires are essential for early detection of obstructive sleep apnea (OSA). The STOP-Bang questionnaire has high sensitivity but low specificity. Dry mouth is a typical clinical sign of OSA. We hypothesised that adding dry mouth in the STOP-Bang questionnaire would improve its specificity.

Study Design: A survey of the incidence of dry mouth was performed in a general population group and suspected sleep apnea clinical population group. Patients with suspected OSA were assessed by laboratory polysomnography and STOP-Bang questionnaire was performed. Adding the option of dry mouth to the OSA screening questionnaire resulted in a new quesionnaire, where cut-off value, diagnostic efficacy and the predictive parameters (sensitivity, specificity, positive predictive value and negative predictive value) were explored.

Results: (In the 912 general population group, the incidence of dry mouth in the snoring group (54.0%) was much higher than that in the non-snoring group (30.5%) (p<0.05). In 207 patients with suspected OSA, the incidence of dry mouth in the OSA group was much higher than that in the non-OSA group (p<0.05). The sensitivity and specificity of the STOP-Bang questionnaire were 88.8% and 23.7% for identifying OSA, and 92.2% and 23.1% for identifying moderate and severe OSA, respectively. Adding the option of dry mouth (dry mouth every morning) to the STOP-Bang questionare resulted in a new questionnaire (STOP-Bang-dry-mouth questionnarie) with 9 items. Its sensitivity and specificity were 81.70% and 42.10% for identifying OSA, and 89.10% and 42.30% for identifying moderate and severe OSA, respectively.

Conclusions: The dry mouth symptom correlated with snoring and sleep apnea. The specificity of the STOP-Bang questionnaire can be improved by integrating dry mouth. The diagnostic accuracy of the STOP-Bang-dry mouth questionnaire is yet to be further verified in prospective studies.