title: Trends in prevalence of patient case-mix adjusters used in the Medicare dialysis payment system.
abstract: OBJECTIVE
  The Medicare End-Stage Renal Disease Prospective Payment System (PPS) used data from 2006-08 to set weights for each case-mix adjuster that is part of the bundled payment formula. The details of the population case-mix were not made public, and little is known about consistency of case-mix over time. This study estimated the prevalence of case-mix adjusters during 2006-2008 and analyzed changes in case-mix prevalence from 2000-2008.
  
  
  METHODS
  Cross-sectional cohort study using United States Renal Data System data for Medicare dialysis patients. Three 3-year cohorts (2000-02, 2003-05, 2006-08) were analyzed for changes over time in case-mix prevalence.
  
  
  RESULTS
  Double-digit trends were observed in many case-mix categories between 2000-02 and 2006-08. Large declines were observed in prevalence of patients with low BMI, pericarditis, new to dialysis, and ages 18-44. Large increases were observed in chronic co-morbidities, pneumonia and age cohort 80+.
  
  
  CONCLUSIONS
  Substantial changes in case-mix adjuster prevalence suggest the PPS payment formula should be regularly updated.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hollenbeak
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Rubin
authors.forename: Spiros
authors.initials: S
authors.lastname: Tzivelekis
authors.forename: J Mark
authors.initials: JM
authors.lastname: Stephens
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003953:Diagnosis-Related Groups; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000191:economics* / Q000628:therapy*; D008297:Male; D006278:Medicare / Q000191:economics*; D008875:Middle Aged; D015995:Prevalence; D011445:Prospective Payment System / Q000191:economics*; D006435:Renal Dialysis / Q000191:economics*; D012189:Retrospective Studies; D020379:Risk Adjustment; D012307:Risk Factors; D014481:United States