title: Growth of intensive care unit resource use and its estimated cost in Medicare.
abstract: OBJECTIVE
  The past 10-15 yrs brought significant changes in the United States healthcare system. Effects on Medicare intensive care unit use and costs are unknown. Intensive care unit costs are estimated using the Russell equation with a ratio of intensive care unit to floor cost per day, or "R value," of 3, which may no longer be valid. We sought to determine contemporary Medicare intensive care unit resource use, costs, and R values; whether these vary by patient and hospital characteristics; and the impact of updated values on estimated intensive care unit costs.
  
  
  METHODS
  Retrospective analysis of Medicare Inpatient Prospective Payment System hospitalizations from 1994 to 2004 using Medicare Provider Analysis and Review files.
  
  
  METHODS
  All nonfederal acute care US hospitals paid through the Inpatient Prospective Payment System.
  
  
  METHODS
  Inpatient prospective payment system hospitalizations from 1994 to 2004 (n = 121,747, 260).
  
  
  METHODS
  None.
  
  
  RESULTS
  We examined resource use and costs (adjusted to y2004$), calculating intensive care unit and floor costs directly and using these to generate year-specific R values. By 2004, 33% of Medicare hospitalizations had intensive care unit or coronary care unit care, with more than half of the increase in total hospitalizations because of additional intensive care unit hospitalizations. Adjusted intensive care unit cost per day remained stable ($2,616 vs. $2,575; 1994 vs 2004), yet adjusted floor cost per day rose substantially ($1,027 vs. $1,488) driven by decreased floor length of stay. Annual adjusted Medicare intensive care unit costs increased 36% to $32.3B, largely because of increased utilization. R values decreased progressively from 2.55 to 1.73, were lower for surgical vs. medical admissions and survivors vs. nonsurvivors, but varied little by hospital characteristics. An R value of 3 overestimated Medicare intensive care unit costs by 17.6% ($5.7 billion) in 2004.
  
  
  CONCLUSIONS
  Medicare intensive care unit use is rising rapidly and will likely continue to do so. Despite significant healthcare system changes, adjusted daily critical care costs remained stable, yet care outside the intensive care unit became more expensive. To track intensive care unit cost over time, year-specific R values should be used.
authors.affiliation: Department of Critical Care Medicine, CRISMA Laboratory, University of Pittsburgh, Pittsburgh, PA, USA. milbrandteb@upmc.edu
authors.forename: Eric B
authors.initials: EB
authors.lastname: Milbrandt
authors.forename: Alexander
authors.initials: A
authors.lastname: Kersten
authors.forename: Malik T
authors.initials: MT
authors.lastname: Rahim
authors.forename: Tony T
authors.initials: TT
authors.lastname: Dremsizov
authors.forename: Gilles
authors.initials: G
authors.lastname: Clermont
authors.forename: Liesl M
authors.initials: LM
authors.lastname: Cooper
authors.forename: Derek C
authors.initials: DC
authors.lastname: Angus
authors.forename: Walter T
authors.initials: WT
authors.lastname: Linde-Zwirble
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006739:Hospital Administration / Q000191:economics*; D017721:Hospital Costs / Q000639:trends*; D006801:Humans; D007362:Intensive Care Units / Q000191:economics*; D007902:Length of Stay / Q000191:economics / Q000639:trends; D008297:Male; D006278:Medicare / Q000191:economics*; D008875:Middle Aged; D011445:Prospective Payment System / Q000191:economics; D012189:Retrospective Studies; D012737:Sex Factors; D012959:Socioeconomic Factors; D014481:United States