O006 Major adverse cardiovascular events in severe Obstructive Sleep Apnoea: Associations with symptom subtypes and symptom burden

BACKGROUND: Obstructive sleep apnoea (OSA) is a heterogeneous disorder with certain phenotypes at increased risk of major adverse cardiovascular events (MACE). We investigated whether symptom subtypes and/or symptom burden are useful predictors of MACE risk in severe OSA. METHOD: In a longitudinal sleep clinic cohort with apnoea-hypopnoea index ≥30 events/hour (n=1767), we investigated 19 OSA-related symptoms across four symptom domains (upper airway [UA], insomnia and disturbed sleep, morning, and daytime sleepiness) and the Epworth Sleepiness Scale score. Latent class analysis identified five symptom subtypes. A symptom burden score (0–8) was developed by selecting the two symptoms from each domain most strongly associated with MACE. Multivariable-adjusted associations of subtypes and symptom burden with future MACE were investigated using Cox regressions. RESULTS: Over a median follow-up of 7 years, 18.7% developed MACE. Relative to the moderately sleepy subtype, the disturbed sleep (adjusted hazard ratio [HR], 1.65; 95%CI, 1.15–2.37) and UA symptoms predominant (HR, 1.57; 95%CI, 1.05–2.34) subtypes showed increased MACE risk. There was a graded increase in MACE risk with increasing symptom burden score (adjusted p for linear trend = 0.003). Compared to patients that reported ≤2 of 8 symptoms, those with ≥7 symptoms showed an independent risk for MACE (HR, 1.77; 95%CI, 1.12–2.77). DISCUSSION: Both symptom subtypes and symptom burden may help identify severe OSA patients at increased risk of MACE. However, our novel symptom burden score may have more clinical utility as it is an easily calculated summative measure of OSA-related symptoms that allows objective comparisons across diverse patient populations.