title: Case volume, quality of care, and care efficiency in coronary artery bypass surgery.
abstract: BACKGROUND
  How case volume and quality of care relate to hospital costs or length of stay (LOS) are important questions as we seek to improve the value of health care.
  
  
  METHODS
  We conducted an observational study of patients 18 years or older who underwent coronary artery bypass grafting surgery in a network of US hospitals. Case volumes were estimated using our data set. Quality was assessed by whether recommended medications and services were not received in ideal patients, as well as the overall number of measures missed. We used multivariable hierarchical models to estimate the effects of case volume and quality on hospital cost and LOS.
  
  
  RESULTS
  The majority of hospitals (51%) and physicians (78%) were lowest-volume providers, and only 18% of patients received all quality of care measures. Median LOS was 7 days (interquartile range [IQR], 6-11 days), and median costs were $25 140 (IQR, $19 677-$33 121). In analyses adjusted for patient and site characteristics, lowest-volume hospitals had 19.8% higher costs (95% CI, 3.9%-38.0% higher); adjusting for care quality did not eliminate differences in costs. Low surgeon volume was also associated with higher costs, though less strongly (3.1% higher costs [95% CI, 0.6%-5.6% higher]). Individual quality measures had inconsistent associations with costs or LOS, but patients who had no quality measures missed had much shorter LOS and lower costs than those who missed even one.
  
  
  CONCLUSIONS
  Avoiding lowest-volume hospitals and maximizing quality are separate approaches to improving health care efficiency through reducing costs of coronary bypass surgery.
authors.affiliation: Department of Medicine Hospitalist Group, University of California-San Francisco, 505 Parnassus Avenue, San Francisco, CA 94143-0131, USA. ada@medicine.ucsf.edu
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Auerbach
authors.forename: Joan F
authors.initials: JF
authors.lastname: Hilton
authors.forename: Judith
authors.initials: J
authors.lastname: Maselli
authors.forename: Penelope S
authors.initials: PS
authors.lastname: Pekow
authors.forename: Michael B
authors.initials: MB
authors.lastname: Rothberg
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lindenauer
mesh_terms: D000368:Aged; D002140:California; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000191:economics / Q000592:standards / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000191:economics* / Q000601:surgery*; D005260:Female; D017721:Hospital Costs; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay; D008297:Male; D008499:Medical Records; D017063:Outcome Assessment, Health Care; D019984:Quality Indicators, Health Care; D011787:Quality of Health Care; D012189:Retrospective Studies; D016896:Treatment Outcome