title: Present-at-admission diagnoses improve mortality risk adjustment and allow more accurate assessment of the relationship between volume of lung cancer operations and mortality risk.
abstract: BACKGROUND
  Mortality risk adjustment is a key component of studies that examine the statistical relationship between hospital lung cancer operation volume and in-hospital mortality. Previous studies of this relationship have used different methods of adjusting for factors that influence mortality risk, but none have adjusted for differences in comorbid disease using only diagnoses identified as present-at-admission.
  
  
  METHODS
  This study uses adjustments for conditions identified as present-at-admission to examine the statistical relationship between the volume of lung cancer operations and mortality among 14,456 California hospital patients, and compares these results to other methods of risk adjustment similar to those used in previous studies.
  
  
  RESULTS
  Mortality risk adjustment using present-at-admission diagnoses yielded better discrimination and explained more of the variability in observed deaths. Large increases in hospital procedure volume were associated with much smaller decreases in mortality risk than those estimated using comparable risk-adjustment models.
  
  
  CONCLUSIONS
  Present-at-admission diagnoses can be used to improve mortality risk adjustment and may allow a more accurate assessment of the relationship between procedure volume and mortality risk.
authors.affiliation: Department of Health Evaluation Sciences, University of Virginia, School of Medicine, Charlottesville 22908-0821, USA. gstukenborg@virginia.edu
authors.forename: George J
authors.initials: GJ
authors.lastname: Stukenborg
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Kilbridge
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Wagner
authors.forename: Frank E
authors.initials: FE
authors.lastname: Harrell
authors.forename: M Norman
authors.initials: MN
authors.lastname: Oliver
authors.forename: Jason A
authors.initials: JA
authors.lastname: Lyman
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Einbinder
authors.forename: Alfred F
authors.initials: AF
authors.lastname: Connors
mesh_terms: D015897:Comorbidity; D003955:Diagnostic Tests, Routine; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate