title: Delirium and coma evaluated in mechanically ventilated patients in the intensive care unit in Japan: a multi-institutional prospective observational study.
abstract: OBJECTIVE
  The object of this study is to evaluate the prevalence and effects of delirium on 28-day mortality in critically ill patients on mechanical ventilation in Japan.
  
  
  METHODS
  Prospective cohort study was conducted in medical and surgical intensive care units (ICUs) of 24 medical centers. Patients were followed up daily for delirium during ICU stay after enrollment. Coma was defined with the Richmond Agitation Sedation Scale score of -4 or -5. Delirium was diagnosed using the Confusion Assessment Method for the ICU. The Cox proportional hazards regression model was used to assess the effects of delirium and coma on 28-day mortality, time to extubation, and time to ICU discharge; delirium and coma were included as time-varying covariates after controlling for age, Acute Physiology and Chronic Health Evaluation II score, ventilator-associated pneumonia, and the reason for intubation with infection.
  
  
  RESULTS
  Of 180 patients, 115 patients (64%) developed delirium. Moreover, 15 patients (8%) died within 28 days after ICU admission, including 7 patients who experienced coma and 8 patients who experienced both coma and delirium. There were no deaths among patients who did not experience coma. Delirium was associated with a shorter time to extubation (hazard ratio [HR], 2.52; 95% confidence interval [CI], 1.65-3.85; P<.001) and a shorter ICU length of stay in comatose patients (HR, 1.59; 95% CI, 1.04-2.44; P=.034), whereas delirium appeared with prolonged time to ICU discharge among patients without coma, although statistical significance was not detected due to limited analytical power (HR, 0.62; 95% CI, 0.34-1.12; P=.114). Delirium during ICU stay was not associated with higher mortality.
  
  
  CONCLUSIONS
  Further study is needed to investigate the discrepancy between these and previous data.
authors.affiliation: Advanced Medical Emergency and Critical Care Center at the Yamaguchi University Hospital, Ube, Yamaguchi, Japan. Electronic address: ryosan-ygc@umin.ac.jp.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Tsuruta
authors.affiliation: Advanced Medical Emergency and Critical Care Center at the Yamaguchi University Hospital, Ube, Yamaguchi, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Oda
authors.affiliation: Department of Biostatistics, Vanderbilt University, Nashville, TN, USA.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Shintani
authors.affiliation: Division of Intensive Care, Department of Anesthesiology & Intensive Care Medicine, Jichi Medical University School of Medicine, Shimotsuke, Tochigi, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Nunomiya
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Kyoto Prefectural University of Medicine, Kyoto, Kyoto, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Advanced Critical Care Center, Aichi Medical University, Nagakute, Aichi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakagawa
authors.affiliation: Ogaki Municipal Hospital, Ogaki, Gifu, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Oida
authors.affiliation: Advanced Medical Emergency & Critical Care Center, Japanese Red Cross Maebashi Hospital, Maebashi, Gunma, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Miyazaki
authors.affiliation: Japanese Red Cross Suwa Hospital, Suwa, Nagano, Japan.
authors.forename: Shigemi
authors.initials: S
authors.lastname: Yabe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060666:Airway Extubation; D015331:Cohort Studies; D003128:Coma / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D016638:Critical Illness / Q000401:mortality; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D007564:Japan; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012121:Respiration, Artificial
keywords: Coma; Confusion Assessment Method for the Intensive Care Unit (CAM-ICU); Delirium; Dexmedetomidine