O036 Respiratory event related oxygen desaturation is predictive of cardiovascular mortality in sleep apnoea patients

INTRODUCTION: Cardiovascular disease (CVD) is the leading cause of death globally. The mechanisms underpinning the development of CVD in OSA are multifaceted and include sympathetic overactivity, endothelial dysfunction, inflammation, and oxidative stress. Nocturnal hypoxaemic burden—the cumulative exposure to hypoxaemia experienced overnight—may contribute to the pathophysiology of CVD. We investigated if polysomnogram SpO2 parameters can predict CVD outcomes in OSA patients. METHODS: Data from the SpO2 signals from 4689 polysomnograms (PSGs) of the Sleep Heart Health Study with CVD mortality outcome and complete covariate information was used. Analysis of the average SpO2 responses to respiratory events revealed a transient response from the event start that extended for four event lengths. Based on the response we developed a respiratory event related oxygen desaturation (REROD) parameter for quantifying the desaturation associated with respiratory events that is readily calculated. The performance of the parameter in predicting CVD death was assessed using an adjusted Cox proportional hazard ratio (HR) analysis and compared to other methods including hypoxic burden, T90 and ODI3. RESULTS: The COX analysis was adjusted for known covariates of CVD. The HR results indicate a dose-response relationship with the highest quintile providing a HR=2.0(95% C.I. 1.3–3.2). DISCUSSION: Our REROD metric predicts CVD mortality independent of confounding covariates and provides prediction performance superior to other hypoxemia metrics. A big advantage of our metric is its computational simplicity and reproducibility. We believe the metric is an important enabling step towards clinical methods that provide CVD risk stratification from the PSG.