緒言とまとめ

Frontiers in the Prevention and Management of Postoperative Delirium：Preface and Comments

　わが国では急速な高齢化社会とともに，手術医療において高齢患者が占める割合は年々増加している。そのなかで，術後せん妄（postoperative delirium：POD）は，術後に高頻度で発症する中枢神経合併症として，臨床現場における重要な課題となっている。PODは，注意障害や意識変容を主体とする急性発症の可逆的病態として古くから知られてきたが，近年ではその臨床的意義が再評価されている。すなわち，PODは単なる一過性の精神症状ではなく，術後回復過程，退院後の生活機能，さらには生命予後にまで影響を及ぼす周術期アウトカムの一つであることが明らかとなってきた。

　As the population of Japan continues to age, the proportion of older patients undergoing surgery continues to increase, making postoperative delirium（POD）a major challenge in perioperative care. POD, once regarded as a transient and reversible neuropsychiatric condition characterized by acute disturbances in attention and consciousness, is now recognized as a clinically significant perioperative outcome. Growing evidence indicates that POD negatively affects patients’ postoperative recovery, prolongs hospital stays, increases healthcare costs, impairs physical and cognitive function after discharge, and is associated with poorer long-term survival. POD imposes a substantial burden not only on patients but also on their families and the healthcare system. In recent years, POD has been conceptualized as part of the broader spectrum of perioperative neurocognitive disorders, which includes pre-existing cognitive vulnerability, early postoperative delirium, and persistent cognitive impairment lasting weeks to months after surgery. This framework shifts the understanding of POD from a complication managed after its onset to a perioperative brain disorder that should be anticipated, prevented, and addressed through early intervention. Several international guidelines have been published in response to the challenges presented by POD. In Japan, the first clinical practice guideline for POD was issued in December 2024 through a joint effort of relevant professional societies. Building on this guideline and recent evidence, this special issue systematically reviews the current understanding of POD, from pathophysiology and risk assessment to prevention and treatment, organized along the perioperative timeline.