title: Demographic and clinical variation of adult intensive care unit utilization from a geographically defined population.
abstract: OBJECTIVE
  To determine population-based rates of adult intensive care unit (ICU) use and evaluate the effects that demographic variables and chronic illness have on ICU utilization.
  
  
  METHODS
  Retrospective, population-based cohort study.
  
  
  METHODS
  Olmsted County, Minnesota.
  
  
  METHODS
  Adult residents admitted to an ICU in 1998.
  
  
  METHODS
  None.
  
  
  RESULTS
  Measurements included demographics, Acute Physiology and Chronic Health Evaluation III score, ICU admission diagnosis, ICU interventions, Charlson comorbidity index and conditions, ICU length of stay (LOS), and ICU, hospital, 1-month, and 1-yr mortalities. Risk of ICU admission and rates of ICU utilization increased substantially with increasing age, peaking in the very elderly. The rates of ICU admission and utilization in those > or =85 yrs old were 58.2 admissions/1,000 residents and 195.8 days/1,000 residents compared with 3.8 admissions/1,000 residents and 11.5 days/1,000 residents in those 18 to 44 yrs old. Residents > or =85 yrs old were 3.75 times as likely (p < .001) to be admitted to the ICU compared with those 18-44 yrs old after controlling for the presence of comorbid illness. ICU admission rates increased with an increasing number of comorbid illnesses. Residents with cardiovascular conditions and renal disease had high rates of ICU admission. Repeat users of the ICU were more likely to have a chronic condition and higher degree of comorbid illness compared with nonrepeat users. ICU mortality was similar across all age groups, except in those > or =85 yrs old, for whom mortality was greater. One-year mortality after ICU admission increased with increasing age.
  
  
  CONCLUSIONS
  Population-based rates of ICU admission and utilization in Olmsted County, Minnesota, increased with age and are highest in the very elderly. The presence of chronic illness, particularly cardiovascular conditions, significantly increases ICU utilization and risk of ICU admission.
authors.affiliation: Division of Pediatric Critical Care Medicine, Department of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. seferian.edward@mayo.edu
authors.forename: Edward G
authors.initials: EG
authors.lastname: Seferian
authors.forename: Bekele
authors.initials: B
authors.lastname: Afessa
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002391:Catchment Area, Health; D002908:Chronic Disease; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D010343:Patient Admission / Q000706:statistics & numerical data; D010359:Patient Readmission / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012720:Severity of Illness Index