O054 What Measure of CPAP Treatment is most closely Associated with Reduced Risk of Future Major Cardiovascular Events (MACE)?

INTRODUCTION: Obstructive sleep apnoea (OSA) is associated with future Major Adverse Cardiovascular Events (MACE). Continuous positive airway pressure (CPAP) is the standard treatment for OSA, but it is not known which measure of CPAP treatment is most closely associated with reduction in future MACE. We compared associations between a novel and a commonly used measure of CPAP treatment and future MACE. MATERIALS AND METHODS: Participants: 2717 adults with moderate-severe OSA attending a tertiary sleep clinic 2006-2010 completed baseline assessments and followed-up for 7years. CPAP treatment: Month-long CPAP trial and periodic review post-trial. OUTCOMES: Time to cardiac death or non-fatal hospitalisations due to MACE, or end of follow-up, using Cox proportional hazards models. PREDICTORS: Average nightly CPAP use and the SARAH index (Sleep-Adjusted Residual AHI), using all available device downloads SARAH index=([AHITreatment×HoursTreatment]+[AHIUntreated×HoursUntreated])/HoursTotalSleepTime COVARIATES: Demographics/comorbidities associated with MACE. RESULTS: MACE occurred in 18% participants. Average nightly use: Compared to zero use, each tertile of increasing use predicted reduction in risk of MACE (tertile-0:ref, tertile-I:HR 0.632, 95%CI 0.484-0.824, p<0.001, tertile-II:HR 0.772, 95%CI 0.602-0.990, p=0.042, tertile-III:HR 0.708, 95%CI 0.553-0.905, p=0.006). SARAH: A dose-response decreasing risk of MACE with decreasing SARAH index tertiles (tertile-I:ref, tertile-II:HR 0.827, 95%CI 0.658-1.039, p= 0.102, tertile-III:HR 0.772, 95%CI 0.614-0.969, p=0.026). CONCLUSIONS: Average nightly CPAP use and SARAH index were associated with a decreased risk of future MACE. The SARAH index showed a dose-response relationship with MACE; suggesting that it may be a better estimate of residual OSA-related cardiovascular stress.