title: Multihospital system membership and patient treatments, expenditures, and outcomes.
abstract: OBJECTIVE
  To determine the relationship between hospital membership in systems and the treatments, expenditures, and outcomes of patients.
  
  
  METHODS
  The Medicare Provider Analysis and Review dataset, for data on Medicare patients admitted to general medical-surgical hospitals between 1985 and 1998 with a diagnosis of acute myocardial infarction (AMI); the American Hospital Association Annual Survey, for data on hospitals.
  
  
  METHODS
  A multivariate regression analysis. An observation is a fee-for-service Medicare AMI patient admitted to a study hospital. Dependent variables include patient transfers, catheterizations, angioplasties or bypass surgeries, 90-day mortality, and Medicare expenditures. Independent variables include system participation, other admission hospital and patient traits, and hospital and year fixed effects. The five-part system definition incorporates the size and location of the index admission hospital and the size and distance of its partners.
  
  
  RESULTS
  While the effects of multihospital system membership on patients are in general limited, patients initially admitted to small rural system hospitals that have big partners within 100 miles experience lower mortality rates than patients initially admitted to independent hospitals. Regression results show that to the extent system hospital patients experience differences in treatments and outcomes relative to patients of independent hospitals, these differences remain even after controlling for the admission hospital's capacity to provide cardiac services.
  
  
  CONCLUSIONS
  Multihospital system participation may affect AMI patient treatment and outcomes through factors other than cardiac service offerings. Additional investigation into the nature of these factors is warranted.
authors.affiliation: University of Pennsylvania Law School, Leonard Davis Institute of Health Economics, Philadelphia 19104, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Madison
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004219:District of Columbia; D005260:Female; D006297:Health Services Accessibility / Q000191:economics*; D006301:Health Services Needs and Demand / Q000191:economics; D006302:Health Services Research; D006299:Health Services for the Aged / Q000191:economics; D006801:Humans; D008297:Male; D006278:Medicare; D009096:Multi-Institutional Systems / Q000191:economics* / Q000592:standards; D009203:Myocardial Infarction / Q000191:economics* / Q000628:therapy*; D017063:Outcome Assessment, Health Care; D010343:Patient Admission / Q000191:economics / Q000706:statistics & numerical data; D010360:Patient Transfer / Q000191:economics / Q000706:statistics & numerical data; D012044:Regression Analysis; D013997:Time Factors