The association between obstructive sleep apnoea, delirium and pain: does it exist or is it just in our heads?

Abstract

The topic of obstructive sleep apnoea (OSA) in the perioperative period has received an increasing amount of attention in recent years. With growing acceptance of the notion that OSA is associated with increased peri-operative risk for a variety of adverse outcomes [1], focus has shifted to providing guidance on the identification and treatment of this patient population in the context of surgery [2, 3]. Despite numerous publications and the release of various guidelines by specialty societies, to date, information on the topic remains incomplete. Consequently, it is widely debated among researchers which peri-operative OSA phenotypes are prone to what type of complications and if these adverse outcomes are preventable through pre-operative identification and adjusted peri-operative management. This information is of major importance in order to help clinicians allocate scarce resources appropriately [4]. It is in this context that the study by Strutz et al. provides valuable information. In their retrospective analysis of data collected for three parent studies, the authors specifically sought to investigate the association between OSA and the occurrence of postoperative delirium as well as increased pain perception. After devising a thorough analysis protocol and employing state of the art methodology, the authors concluded that no such associations exist, at least within the framework of their analysis. They therefore suggested that screening for OSA may not be an effective tool to reduce the burden of these particular events, which are linked to further medical complications and higher resource utilisation. However, they do point out that the rate of delirium among patients with OSA is very high and therefore represents a considerable problem [5]. This publication adds to our knowledge on the subject of delirium and pain in OSA patients for which there is a paucity of literature [5]. The authors based their hypothesis on a relatively small number of previous studies suggesting OSA to be a risk factor for postoperative delirium and increased pain perception. Comparatively though, the data published in this edition of Anaesthesia represent the largest cohort in which these questions have been studied thus far [6, 7]. Qualitative assessment of the study and its design There are several points to be discussed about this remarkable publication. Strutz et al. present an example of how complex analyses of observational data can be conducted in a transparent way that increases confidence in the robustness of results.In an era where observational analyses of secondary data have become the source of much excitement but also significant criticism, it is important to note that in order to maintain the highest level of integrity, the authors have not only formulated and published their analysis plan a priori but also have opened it up to peer review [8]. This allowed for outside input and improvement of their protocol and goes beyond calls for registration of such investigations as suggested previously [9]. Although the c...