P081 Residual daytime sleepiness in CPAP-treated OSA patients

Abstract Introduction Obstructive sleep apnoea (OSA) frequently causes excessive daytime sleepiness (EDS). EDS impairs quality-of-life and can induce motor vehicle accidents or workplace injuries. Treatment dogma would suggest that CPAP (continuous positive airway pressure), the gold standard treatment, should abolish EDS, but up to 22% of CPAP-treated OSA patients can have residual EDS. Our tertiary health service serves a large catchment within the eastern coast of Australia. We aimed to examine the prevalence and precipitating causes of post-CPAP residual EDS in our local OSA population. Methods This was a single-centre retrospective study. Data set was compiled from the medical records of patients aged ≥18 years presenting to outpatients with OSA diagnosis in 2019-2024. Results Out of 354 patients, 35 (10%) had residual EDS on post-CPAP commencement follow-up. Median age was 58 years (IQR 54-75); 60% (n = 21) were males. Chronic pain and mental health co-morbidities were prevalent in 46%. Median Epworth Sleepiness Scale and Apnoea-Hypopnoea Index at diagnosis were 14 and 31.7, respectively. Most had home-based diagnostic study (n = 20) and lab-based CPAP titration (n = 24). 6 repeat in-lab titration studies and 3 vigilance tests were performed to evaluate residual EDS. Co-existing insomnia and CPAP-related issues were commonly identified as causing residual EDS. Conclusion OSA treatment is often undertaken to improve patients’ daytime somnolence and quality-of-life. Therefore, from the outset, patients should be informed about the CPAP acclimatisation process and of co-existing non-OSA conditions that may be perpetuating their EDS. Insomnia is not uncommon in modern society and should be screened for at index clinic reviews for OSA.