title: Hospital administrative database underestimates delirium rate after cardiac surgery.
abstract: OBJECTIVE
  Administrative electronic databases are highly specific for postoperative complications, but they lack sensitivity. The objective of this study was to determine the incidence of delirium after cardiac surgery using a targeted prospectively collected dataset and to compare the findings with the incidence of delirium in the same cohort of patients identified in a hospital administrative database.
  
  
  METHODS
  Following Research Ethics Board approval, we compared delirium rates in a prospectively collected data research database with delirium rates in the same cohort of patients in an administrative hospital database where delirium was identified from codes entered by coding and abstracting staff. Every 12 hr postoperatively, delirium was assessed with a Confusion Assessment Method in the Intensive Care Unit. The administrative database contained the International Classification of Diseases version 10 (ICD-10) codes for patient diagnoses. The ICD-10 codes were extracted from the administrative database for each patient in the research database and were checked for the presence of the ICD-10 code for delirium.
  
  
  RESULTS
  Data from a cohort of 1,528 patients were analyzed. Postoperative delirium was identified in 182 (11.9%) patients (95% confidence interval [CI], 10.3-13.5%) in the research dataset and 46 (3%) patients (95% CI, 2.2-3.8%) in the administrative dataset (P < 0.001). Thirteen (0.85%) patients who were coded for delirium in the administrative database were not identified in the research dataset. The median onset of postoperative delirium in these patients was significantly delayed (4 [3-9] days) compared with patients identified by both datasets (2 [1-9] days) and compared with patients from the research database only (1 [1-14] days) (P = 0.007).
  
  
  CONCLUSIONS
  Postoperative delirium rates after cardiac surgery are underestimated by the hospital administrative database.
authors.affiliation: Department of Anesthesiology, Toronto General Hospital, Eaton North 3-453, 200 Elizabeth Street, Toronto, ON M5G 2C4, Canada. rita.katznelson@uhn.on.ca
authors.forename: Rita
authors.initials: R
authors.lastname: Katznelson
authors.forename: George
authors.initials: G
authors.lastname: Djaiani
authors.forename: Gordon
authors.initials: G
authors.lastname: Tait
authors.forename: Marcin
authors.initials: M
authors.lastname: Wasowicz
authors.forename: Ainsley M
authors.initials: AM
authors.lastname: Sutherland
authors.forename: Rima
authors.initials: R
authors.lastname: Styra
authors.forename: Corina
authors.initials: C
authors.lastname: Lee
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D016208:Databases, Factual / Q000592:standards* / Q000706:statistics & numerical data; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors