P109 Predicting major adverse cardiovascular events using symptom subtypes of severe obstructive sleep apnoea

BACKGROUND: Obstructive sleep apnoea (OSA) is a complex heterogeneous disorder, and patients with similar disease severity present with different symptom profiles and outcomes. It is unclear whether OSA symptom subtypes independently predict incident major adverse cardiovascular events (MACE). METHOD: Consecutive patients attending a tertiary sleep clinic from 2006 to 2010 were prospectively investigated and linked to administrative health data. Data from 1,767 patients with severe OSA (apnoea-hypopnoea index ≥30 events/hour) were used in latent class analysis to identify symptom subtypes. Associations between symptom subtypes and incident MACE were assessed using Cox proportional hazards models, with adjustment for known cardiovascular risk factors. RESULTS: On average, patients were middle-aged (mean± SD: 52.5±13.2 years), obese (BMI, 35.4±7.9 kg/m²), and male (71.7%). Four symptom subtypes were identified: high symptom burden: severe sleepiness (26.0%), high symptom burden: sleep onset insomnia (34.8%), moderate symptom burden (18.4%), and minimal symptoms (20.7%). Over a median follow-up of 7 years, 330 (18.7%) patients developed MACE. After adjustment for covariates, the high symptom burden: sleep onset insomnia subtype was associated with increased risk for MACE relative to those with moderate (HR, 1.59; 95%CI, 1.12–2.25; P=0.010) or minimal (HR, 1.47; 95%CI, 1.07–2.03; P=0.018) symptom burden. DISCUSSION: Distinct symptom subtypes can be identified among severe OSA patients. In symptomatic patients, those with a high prevalence of sleep onset insomnia were at increased risk of MACE, relative to those with moderate or minimal symptom burden. Our findings suggest that symptom subtypes may be clinically relevant in risk stratification for MACE in severe OSA.