title: Intensive care utilization and outcomes after high-risk surgery in Scotland: a population-based cohort study.
abstract: BACKGROUND
  The optimal perioperative use of intensive care unit (ICU) resources is not yet defined. We sought to determine the effect of ICU admission on perioperative (30 day) and long-term mortality.
  
  
  METHODS
  This was an observational study of all surgical patients in Scotland during 2005-7 followed up until 2012. Patient, operative, and care process factors were extracted. The primary outcome was perioperative mortality; secondary outcomes were 1 and 4 yr mortality. Multivariable regression was used to construct a risk prediction model to allow standard-risk and high-risk groups to be defined based on deciles of predicted perioperative mortality risk, and to determine the effect of ICU admission (direct from theatre; indirect after initial care on ward; no ICU admission) on outcome adjusted for confounders.
  
  
  RESULTS
  There were 572 598 patients included. The risk model performed well (c-index 0.92). Perioperative mortality occurred in 1125 (0.2%) in the standard-risk group (n=510 979) and in 3636 (6.4%) in the high-risk group (n=56 785). Patients with no ICU admission within 7 days of surgery had the lowest perioperative mortality (whole cohort 0.7%; high-risk cohort 5.3%). Indirect ICU admission was associated with a higher risk of perioperative mortality when compared with direct admission for the whole cohort (20.9 vs 12.1%; adjusted odds ratio 2.39, 95% confidence interval 2.01-2.84; P<0.01) and for high-risk patients (26.2 vs 17.8%; adjusted odds ratio 1.64, 95% confidence interval 1.37-1.96; P<0.01). Compared with direct ICU admission, indirectly admitted patients had higher severity of illness on admission, required more organ support, and had an increased duration of ICU stay.
  
  
  CONCLUSIONS
  Indirect ICU admission was associated with increased mortality and increased requirement for organ support.
  
  
  BACKGROUND
  UKCRN registry no. 15761.
authors.affiliation: Department of Anaesthesia, Critical Care and Pain Medicine michael.gillies@ed.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: Gillies
authors.affiliation: Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: E M
authors.initials: EM
authors.lastname: Harrison
authors.affiliation: Faculty of Medicine and Dentistry, Queen Mary University London, London, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Pearse
authors.affiliation: Department of Anaesthesia, Critical Care and Pain Medicine.
authors.forename: S
authors.initials: S
authors.lastname: Garrioch
authors.affiliation: NHS Services Scotland, Information Services Division, South Gyle, Edinburgh, UK.
authors.forename: C
authors.initials: C
authors.lastname: Haddow
authors.affiliation: NHS Services Scotland, Information Services Division, South Gyle, Edinburgh, UK.
authors.forename: L
authors.initials: L
authors.lastname: Smyth
authors.affiliation: Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: R
authors.initials: R
authors.lastname: Parks
authors.affiliation: Department of Anaesthesia, Critical Care and Pain Medicine.
authors.forename: T S
authors.initials: TS
authors.lastname: Walsh
authors.affiliation: Department of Anaesthesia, Critical Care and Pain Medicine.|Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK.
authors.forename: N I
authors.initials: NI
authors.lastname: Lone
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006295:Health Resources; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: epidemiology; intensive care; surgery