Intravenous patient-controlled analgesia does not increase the risk of postoperative delirium compared to patient-controlled epidural analgesia: a propensity score-matched retrospective cohort study - Miyoshi, Hirotsugu; Nakamura, Ryuji; Noda, Yuko; Yokomi, Hiroshi; Kamiya, Satoshi; Morio, Atsushi; Watanabe, Tomoyuki; Narasaki, Soushi; Toyota, Yukari; Saeki, Noboru; Hamada, Hiroshi; Tsutsumi, Yasuo M. (Annals of Palliative Medicine, 2021)