Perioperative cognitive disorders. Response to: Postoperative delirium portends descent to dementia

Editor—We read with great interest the recent editorial by Aranake-Chrisinger & Avidan.¹ We were pleased to see that this editorial contains terminology developed over several yr by the multi-disciplinary International Perioperative Cognition Nomenclature Working Group. At the same time, we were surprised and disappointed that the terminology is presented before the official release (in the British Journal of Anaesthesia as well as Anesthesia & Analgesia, Canadian Journal of Anesthesiology, Acta Anaesthesiologica Scandinavica, Journal of Alzheimers Disease and Anesthesiology),² without the necessary definitions or attributions. This was particularly surprising given the senior author of the editorial was privy to the work of this group and reviewed final drafts of the manuscript. We presume this oversight simply reflects enthusiasm for adopting this new nomenclature.

The International Perioperative Cognition Nomenclature Working group consists of a multidisciplinary team established more than two yr ago, to specifically address major shortcomings in terminology used to describe cognitive deficits in patients undergoing anaesthesia and surgery. The development of the recommendations² for these terms was necessary for at least three major reasons. First, the literature on postoperative cognitive dysfunction (POCD) is compromised as a result of variable definitions and criteria, the lack of a clinical component, no actual clinical diagnosis, and often poor research methodology. Second, in order to understand any cognitive impairment or cognitive change temporally associated with anaesthesia and surgery, it is necessary to put this in the context of the overall cognitive trajectory of an individual. Finally, for the first time, the new nomenclature enables the range of perioperative cognitive disorders to be aligned with clinically meaningful terms. The editorial by Aranake-Chrisinger & Avidan¹ presents this concept in Figure 1, but a failure to define the terms makes their use arbitrary and ambiguous. In particular, the term delayed neurocognitive recovery has no precedent in the literature, and until its definition in our nomenclature recomemendations,² has not been previously used to describe or define a decline in cognition observed in the early postoperative period. The terms mild neurocognitive disorder (mild NCD) and major neurocognitive disorder (major NCD) are defined in the DSM-5³ although this source is also not cited. Additionally, until the recommendations by our Working Group, these terms have not been previously used to define cognitive function in the entire perioperative period (Perioperative Cognitive Disorders).

Our work aligns cognitive impairment and decline associated with anaesthesia and surgery with the DSM-5 and National Institute for Aging – Alzheimer’s Association (NIA-AA) definitions and criteria. Timelines are included and reasons for the recommended use of the terms ‘delayed neurocognitive recovery’ to 30 days postoperatively and ‘mild/major NCD – postoperative’ through to 12 months are clearly explained.

We strongly encourage clinicians and researchers to employ these definitions for the assessment of cognitive impairment and cognitive decline, in the hope of tracking cognitive trajectories over the perioperative period and beyond, and in doing so, generate the capacity to interpret any impact of anaesthesia and surgery on the cognitive function of older individuals. We look forward to future use of these terms according to the recommended definitions and timelines presented in an upcoming issue.²

Declaration of interest

None declared.

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