CORRESPONDENCE The SAVE Trial: Has the Importance of CPAP for Preventing Cardiovascular Events been Discounted? Ahmed S. Bahammam 1 • Seithikurippu R. Pandi-Perumal 2 • David Warren Spence 3 • Adam Moscovitch 4 • David L. Streiner 5,6 Received: 3 December 2016 / Accepted: 2 January 2017 / Published online: 17 January 2017 Ó Springer Science+Business Media Singapore 2017 A paper by McEvoy et al. recently appeared in the New England Journal of Medicine concerning the role of con- tinuous positive airway pressure (CPAP) in the prevention of cardiovascular events in patients with obstructive sleep apnea (OSA) [1]. The primary composite end point of the study was death from cardiovascular causes, myocardial infarction, stroke, or hospitalization for unstable angina, heart failure, or transient ischemic attack. The results of this paper, apparently showing that CPAP had no protec- tive effect against various forms of cardiovascular disease (CVD), came as a surprise to us in light of the accumulated evidence linking OSA with CVD. The currently available data from randomized controlled trials (RCTs) have shown that CPAP has beneficial effects on factors associated with CVD such as blood pressure, increased sympathetic activity, endothelial function, and insulin sensitivity [2, 3]. In addition, several observational studies have shown that CPAP use reduces the risk of cardiovascular events due to OSA and cardiovascular related death [2, 3]. The associated editorial by Mokhlesi and Ayas (2016) cited several important issues that might have influenced the results of the McEvoy et al. SAVE trial [4]. These included the duration and timing of CPAP use where the average duration of CPAP per night was 3.3 h. Moreover, the variability of resources in certain geographic locations might have affected the outcome measures [4]. Because of recruitment difficulties, the investigators changed their original sample-size calculation. However, the re-estima- tion was based on primary prevention studies, rather than secondary prevention studies [4]. However, there are other important issues that need to be discussed. An essential criterion for inclusion in the study was a diagnosis of coronary artery disease (CAD) or cere- brovascular disease, which means that the study assessed secondary, not primary prevention [1]. The title failed to reflect this important aspect of the study. To diagnose moderate-to-severe OSA, the investigators measured oxygen desaturation index via a portable moni- toring device ‘‘ApneaLink (AL)’’. Choosing the appropri- ate population is extremely important when considering the use of a portable monitoring device to diagnose OSA. The previous studies that showed positive outcomes with AL have been done on patients who had a high likelihood of having OSA, in addition to excluding patients with con- founding disorders such as respiratory diseases, cardiac diseases, and cerebrovascular diseases [5, 6]. These find- ings, therefore, raise the question of whether AL was the appropriate diagnostic tool in this study. One of the inclusion criteria in the McEvoy et al. paper was a diag- nosis of CVD and cerebrovascular diseases [1]. Therefore, it is possible that a good proportion of the included patients & Ahmed S. Bahammam ashammam2@gmail.com & Seithikurippu R. Pandi-Perumal pandiperumal2017@gmail.com 1 Department of Medicine, College of Medicine, The University Sleep Disorders Center, King Saud University, Riyadh, Saudi Arabia 2 Somnogen Canada Inc., Toronto, ON, Canada 3 652 Dufferin Street, Toronto, ON M6K 2B4, Canada 4 Sleep and Fatigue Institute, The University of Calgary, Calgary, Canada 5 Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, ON, Canada 6 Department of Psychiatry, University of Toronto, Toronto, ON, Canada 123 Sleep Vigilance (2017) 1:47–48 DOI 10.1007/s41782-017-0003-z