title: Outcome analysis using hazard function methodology.
abstract: BACKGROUND
  The hazard function is the instantaneous rate of occurrence of a time-related event, such as death. Methods exist to determine the hazard function from clinical outcome (follow-up) data, to identify risk factors for higher hazard, and to generate patient-specific predictions. In this article, hazard function methodology is extended to the arena of healthcare costs.
  
  
  METHODS
  Using a compartmental analogue, a hazard function method is introduced to analyze patient-specific distributions of hospital costs, charges, or length of stay when these are truncated by the competing risk of in-hospital death. Another hazard function method is proposed to analyze time-related healthcare costs, exploiting weighted repeated events theory.
  
  
  RESULTS
  Successful application of the hospital costs methodology in the hazard function domain is demonstrated for length-of-stay data after coronary artery bypass grafting. A previously reported analysis of variable morbidity from repeated thromboembolic events illustrates the weighted events methods.
  
  
  CONCLUSIONS
  Existing hazard function methodology can be extended to analyze healthcare costs, either of a single episode of care or of multiple time-related episodes.
authors.affiliation: Department of Surgery, University of Alabama at Birmingham 35294-0007, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Blackstone
mesh_terms: D000368:Aged; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D017202:Myocardial Ischemia / Q000191:economics / Q000401:mortality*; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors