Obstructive Sleep Apnea According to Positional Dependency: Propensity Score Matching Analysis

Background and Objectives Obstructive sleep apnea (OSA) patients can be classified into two groups based on the relationship between their supine and non-supine apnea-hypopnea index (AHI). This study compared the clinical characteristics of positional and non-positional OSA patients and identified factors influencing OSA severity in each group.Subjects and Method The positional OSA group consisted of patients with a supine AHI more than twice the value of the non-supine AHI. Propensity-score matching (PSM) was performed to balance AHI differences between the groups. Demographic data, symptom scores, physical examination results, and polysomnography (PSG) data were analyzed. Compliance data for patients using auto-adjusting positive airway pressure (APAP) were also collected.Results Ninty patients in each group were matched through PSM. The non-positional OSA group exhibited significantly higher daytime sleepiness scores (<i>p</i>=0.040). There were no significant differences in sex, age, body mass index (BMI), or physical examination results. On the other hand, the PSG data of positional OSA group showed significantly higher average (<i>p</i>=0.031) and as well as lowest oxygen saturation (<i>p</i>=0.046). BMI was a risk factor for severe OSA in both groups, with age being significant in the positional group and sex and retropalatal obstruction in the non-positional group. Although non-positional patients utilized APAP more frequently than the positional group, there were no significant differences in compliance.Conclusion Positional dependency in OSA patients is associated with varying symptom severity, the PSG findings and PAP usage. Factors like BMI, age, sex, and the level of obstruction in severe OSA differed depending on positional dependency.