title: Smoking increases the risk of delirium for older inpatients: a prospective population-based study.
abstract: OBJECTIVE
  To investigate the association between smoking in the older population and the risk of inpatient delirium, which is common and has adverse consequences.
  
  
  METHODS
  Participants (N=3754) were insurants aged ≥55years of the largest German statutory health insurance company, who enrolled in a 6-year prospective population-based study. Baseline smoking, adjusted for age, sex, depressive symptoms, cognitive impairment and alcohol consumption, was analyzed as risk factor of inpatient delirium. Results are presented as hazard ratios (HRs) and 95% confidence intervals (95% CIs).
  
  
  RESULTS
  Three-hundred seventy-three (10.0%) participants were smokers at baseline, 865 (23.0%) were quitters and 2516 (67.0%) were lifelong abstainers. Mean pack-years of smokers and quitters were 23.8 (S.D.=22.4). Sixty-one (1.6%) received a diagnosis of inpatient delirium. Smokers had an increased risk of delirium compared to abstainers in the fully adjusted model (HR=2.87, 95% CI 1.24-6.66). Quitters and abstainers did not differ (HR=0.79, 95% CI 0.37-1.72). Comparing smokers and quitters, current smoking status (HR=3.22, 95% CI 1.20-8.62) but not pack-years [residual χ(2)(1)=0.25, P=.874] were associated with inpatient delirium.
  
  
  CONCLUSIONS
  Only current smoking but not being a quitter and the lifetime amount smoked were associated with inpatient delirium, indicating that acute nicotine withdrawal may represent a relevant pathogenic mechanism.
authors.affiliation: Department of Psychiatry and Psychotherapy, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany. Electronic address: johannes.hessler@lrz.tum.de.
authors.forename: Johannes Baltasar
authors.initials: JB
authors.lastname: Hessler
authors.affiliation: Department of Psychiatry and Psychotherapy, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany. Electronic address: m.broenner@mnet-online.de.
authors.forename: Monika
authors.initials: M
authors.lastname: Brönner
authors.affiliation: Department of Psychiatry and Psychotherapy, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany; Department of Neurology, Kliniken Südostbayern-Klinikum Traunstein, Cuno-Niggl-Strasse 3, 83278 Traunstein, Germany. Electronic address: thorleif@etgen.de.
authors.forename: Thorleif
authors.initials: T
authors.lastname: Etgen
authors.affiliation: INVADE Study Group, Karl-Böhm-Strasse 32, 85598 Baldham, Germany. Electronic address: gotzler-med@t-online.de.
authors.forename: Othmar
authors.initials: O
authors.lastname: Gotzler
authors.affiliation: Department of Psychiatry and Psychotherapy, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany. Electronic address: hans.foerstl@lrz.tum.de.
authors.forename: Hans
authors.initials: H
authors.lastname: Förstl
authors.affiliation: Department of Neurology, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany. Electronic address: poppert@gmx.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Poppert
authors.affiliation: Department of Neurology, Benedictus Krankenhaus Tutzing, Bahnhofstrasse 5, 82327 Tutzing, Germany. Electronic address: d.sander@mac.com.
authors.forename: Dirk
authors.initials: D
authors.lastname: Sander
authors.affiliation: Department of Psychiatry and Psychotherapy, Technische Universität München Klinikum Rechts der Isar, Ismaninger Strasse 22, 81675 Munich, Germany. Electronic address: h.bickel@lrz.tum.de.
authors.forename: Horst
authors.initials: H
authors.lastname: Bickel
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003693:Delirium / Q000453:epidemiology*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000009:adverse effects*; D018722:Nicotinic Agonists / Q000009:adverse effects*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D013375:Substance Withdrawal Syndrome / Q000209:etiology*
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine
keywords: Acetylcholine; Hospital; Nicotine; Prevention; Withdrawal