title: The impact of lymphopenia on delirium in ICU patients.
abstract: BACKGROUND
  Immunosuppressed states may predispose patients to development of acute brain injury during times of critical illness. Lymphopenia is a non-specific yet commonly used bedside marker of immunosuppressed states.
  
  
  METHODS
  We examined whether lymphopenia would predict development of acute brain dysfunction (delirium and/or coma) in 518 patients enrolled in the Bringing to Light the Risk Factors and Incidence of Neuropsychological Dysfunction in ICU Survivors (BRAIN-ICU) study in medical and surgical ICUs of a tertiary care, university-based medical center. Utilizing proportional odds logistic regression and Cox proportional hazards survival analysis, we assessed the relationship between pre-enrollment lymphocytes and subsequent cognitive outcomes including delirium- and coma-free days (DCFDs) and 30-day mortality.
  
  
  RESULTS
  There were no statistically significant associations between lymphocytes and DCFDs (p = 0.17); additionally, the relationship between lymphocytes and mortality was not statistically significant (p = 0.71). Among 259 patients without history of cancer or diabetes, there was no statistically significant association between lymphocytes and DCFDs (p = 0.07).
  
  
  CONCLUSIONS
  lymphopenia, a commonly used bedside marker of immunosuppression, does not appear to be a marker of risk for acute brain injury (delirium/coma) or 30-day mortality in general medical/surgical ICU patients.
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Inoue
authors.affiliation: Division of General Internal Medicine and Public Health, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Veterans Affairs Tennessee Valley Geriatric Research, Education and Clinical Center (GRECC), Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Eduard E
authors.initials: EE
authors.lastname: Vasilevskis
authors.affiliation: Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Pratik P
authors.initials: PP
authors.lastname: Pandharipande
authors.affiliation: Division of Allergy/Pulmonary/Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Veterans Affairs Tennessee Valley Geriatric Research, Education and Clinical Center (GRECC), Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Girard
authors.affiliation: Department of Biostatistics, Vanderbilt University School of Medicine Nashville, Tennessee, United States of America.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Graves
authors.affiliation: Department of Biostatistics, Vanderbilt University School of Medicine Nashville, Tennessee, United States of America.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Thompson
authors.affiliation: Department of Biostatistics, Vanderbilt University School of Medicine Nashville, Tennessee, United States of America.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Shintani
authors.affiliation: Division of Allergy/Pulmonary/Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Veterans Affairs Tennessee Valley Geriatric Research, Education and Clinical Center (GRECC), Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: E Wesley
authors.initials: EW
authors.lastname: Ely
mesh_terms: D000368:Aged; D003128:Coma / Q000175:diagnosis / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D016638:Critical Illness; D003693:Delirium / Q000175:diagnosis / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007362:Intensive Care Units; D016015:Logistic Models; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000473:pathology; D008231:Lymphopenia / Q000175:diagnosis / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D062606:Tertiary Care Centers