title: Validation of a consensus method for identifying delirium from hospital records.
abstract: BACKGROUND
  Delirium is increasingly considered to be an important determinant of trajectories of cognitive decline. Therefore, analyses of existing cohort studies measuring cognitive outcomes could benefit from methods to ascertain a retrospective delirium diagnosis. This study aimed to develop and validate such a method for delirium detection using routine medical records in UK and Ireland.
  
  
  METHODS
  A point prevalence study of delirium provided the reference-standard ratings for delirium diagnosis. Blinded to study results, clinical vignettes were compiled from participants' medical records in a standardised manner, describing any relevant delirium symptoms recorded in the whole case record for the period leading up to case-ascertainment. An expert panel rated each vignette as unlikely, possible, or probable delirium and disagreements were resolved by consensus.
  
  
  RESULTS
  From 95 case records, 424 vignettes were abstracted by 5 trained clinicians. There were 29 delirium cases according to the reference standard. Median age of subjects was 76.6 years (interquartile range 54.6 to 82.5). Against the original study DSM-IV diagnosis, the chart abstraction method gave a positive likelihood ratio (LR) of 7.8 (95% CI 5.7-12.0) and the negative LR of 0.45 (95% CI 0.40-0.47) for probable delirium (sensitivity 0.58 (95% CI 0.53-0.62); specificity 0.93 (95% CI 0.90-0.95); AUC 0.86 (95% CI 0.82-0.89)). The method diagnosed possible delirium with positive LR 3.5 (95% CI 2.9-4.3) and negative LR 0.15 (95% CI 0.11-0.21) (sensitivity 0.89 (95% CI 0.85-0.91); specificity 0.75 (95% CI 0.71-0.79); AUC 0.86 (95% CI 0.80-0.89)).
  
  
  CONCLUSIONS
  This chart abstraction method can retrospectively diagnose delirium in hospitalised patients with good accuracy. This has potential for retrospectively identifying delirium in cohort studies where routine medical records are available. This example of record linkage between hospitalisations and epidemiological data may lead to further insights into the inter-relationship between acute illness, as an exposure, for a range of chronic health outcomes.
authors.affiliation: Centre for Gerontology and Rehabilitation, School of Medicine, St. Finbarr's Hospital, Cork, Ireland.
authors.forename: Elvira
authors.initials: E
authors.lastname: Kuhn
authors.affiliation: School of Medicine, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Du
authors.affiliation: Centre for Gerontology and Rehabilitation, School of Medicine, St. Finbarr's Hospital, Cork, Ireland.
authors.forename: Keith
authors.initials: K
authors.lastname: McGrath
authors.affiliation: Centre for Gerontology and Rehabilitation, School of Medicine, St. Finbarr's Hospital, Cork, Ireland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Coveney
authors.affiliation: Centre for Gerontology and Rehabilitation, School of Medicine, St. Finbarr's Hospital, Cork, Ireland.
authors.forename: Niamh
authors.initials: N
authors.lastname: O'Regan
authors.affiliation: Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Richardson
authors.affiliation: Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Teodorczuk
authors.affiliation: Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Louise
authors.initials: L
authors.lastname: Allan
authors.affiliation: Department of Clinical Gerontology, Kings College Hospital NHS Foundation Trust, London, United Kingdom.
authors.forename: Dan
authors.initials: D
authors.lastname: Wilson
authors.affiliation: Aging Brain Center, Institute for Aging Research, Hebrew SeniorLife, and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, United States of America.
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Inouye
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom; Edinburgh Delirium Research Group, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Alasdair M J
authors.initials: AM
authors.lastname: MacLullich
authors.affiliation: Department of Psychiatry, University of Limerick, Limerick, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Meagher
authors.affiliation: Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Carol
authors.initials: C
authors.lastname: Brayne
authors.affiliation: Centre for Gerontology and Rehabilitation, School of Medicine, St. Finbarr's Hospital, Cork, Ireland.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Timmons
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom; Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom; MRC Unit for Lifelong Health and Ageing, University College London, London, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Davis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D032921:Consensus; D003693:Delirium / Q000175:diagnosis*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D012015:Reference Standards; D015203:Reproducibility of Results; D012189:Retrospective Studies