Background: The aim of this study was to investigate the predictive value of snoring frequency in the diagnosis and severity of obstructive sleep apnea. Methods: Patients who underwent polysomnography with one or more of the following characteristics were included: 1) sleepiness, non-restorative sleep, fatigue, or insomnia symptoms; 2) arousal due to cessation of breathing or the occurrence of gasping or choking when waking up; and 3) habitual snoring, breathing interruptions, or both, noted by a bed partner or other observer. We analyzed the differences in clinical and polysomnographic variables between patients with and without obstructive sleep apnea and investigated the associations of those variables with obstructive sleep apnea severity. Results: One hundred ninety-three patients met the inclusion criteria, and 145 of the 193 patients were diagnosed with obstructive sleep apnea. Multiple logistic regression analysis showed that large neck circumference (p = 0.0054) and high snoring index (p = 0.0119) were independent predictors for obstructive sleep apnea. Moreover, between the obstructive sleep apnea severity groups, there was a strong tendency of difference in body mass index (p = 0.0441) and neck circumference (p = 0.0846). However, there was no significant difference in snoring frequency according to obstructive sleep apnea severity (p = 0.4914). Conclusions: We confirmed that snoring frequency is a predictor of obstructive sleep apnea. In addition, we showed for the first time that snoring frequency is not associated with obstructive sleep apnea severity, thus it is not a valuable marker for predicting obstructive sleep apnea severity.
