To assess association between various comorbidities & mild vs moderate rapid eye movement (REM) predominant obstructive sleep apnea (OSA).

Mild OSA is defined as apnea hypopnea index (AHI) of 5-15 events per hour of sleep, moderate as 15-30 & severe >30 events per hour of sleep. Patients with REM-predominant OSA tend to have an overall low AHI by virtue of the disproportionately lower percent of REM sleep as a function of total sleep duration. REM predominant OSA is classified as REM AHI >5 with a total REM sleep duration of at least 30 minutes. Compared with non-rapid eye movement (NREM) sleep, REM sleep is associated with higher autonomic nervous system & cardiorespiratory instability in healthy individuals & more so in patients with OSA. However, it is unknown whether there is any difference in prevalence of various comorbidities in mild vs moderate REM AHI.

We conducted a single center cross-sectional retrospective study on patients aged >18 years who had REM AHI of 5-30. Patients were divided into two groups, those who have REM AHI 5-15 & 15-30. Statistical analysis (frequency & chi square test) was conducted using IBM-SPSS:24 with P<0.05 &  power of study > 80%.

A total of 533 patients with a mean age of 53.24±14.55 years were analyzed. Of those, 342 people had AHI of 5 -15 & 191 patients had AHI 15-30. Mild as well as moderate REM OSA were significantly associated with atrial fibrillation, Type-2 diabetes & Restless leg syndrome when adjusted for age & BMI (P<0.05). Additionally, they were significantly associated with pulmonary hypertension & mood disorder when adjusted for BMI only (p<0.05). There was no significant correlation between the comorbidities & REM AHI when adjusted for gender (p>0.05).

Even mild REM OSA demonstrated statistically significant association to comorbidities similar to moderate REM OSA. Further studies are needed to evaluate the clinical significance of mild REM OSA.