title: Institutional variation in ordering complete blood counts for children hospitalized with bronchiolitis.
abstract: BACKGROUND
  In the evaluation of infants with bronchiolitis there is little evidence to support the use of diagnostic testing, particularly complete blood counts (CBCs). However, the extent to which CBCs are ordered in the evaluation of infants with bronchiolitis is unknown.
  
  
  OBJECTIVE
  (1) To determine institutional variability in ordering of initial and repeat CBCs in infants hospitalized with bronchiolitis; (2) to examine the relationship between proportion of admissions with CBCs and mean hospital charges.
  
  
  METHODS
  We analyzed the Pediatric Health Information System database, which contains demographic and diagnostic data from 30 U.S. children's hospitals. We restricted our analysis to children less than 12 months old with a primary discharge diagnosis of bronchiolitis and an APR-DRG of bronchiolitis/asthma. We performed multivariate ANOVA to examine variability in initial and repeat CBC ordering across hospitals, controlling for potential confounders. We used stratified logistic regression to determine which factors were associated with repeat CBCs. We examined the relationship between proportion of admissions with CBCs and mean hospital charges using t tests.
  
  
  RESULTS
  17,397 children were included in the analysis, and 48.2% had at least 1 CBC, whereas 7.8% had more than 1 CBC. The proportion of admissions with initial (23.2%-70.2%) and repeat (0%-18.6%) CBCs varied significantly across hospitals. Compared to those hospitals with the lowest proportion of admissions with CBCs, hospitals with higher proportions of CBCs had significantly higher mean hospital stay charges.
  
  
  CONCLUSIONS
  Given the potential downstream medical and financial consequences associated with CBC ordering in evaluation of infants with bronchiolitis, explanations for institutional variation warrant exploration.
authors.affiliation: Division of General Pediatrics, University of Michigan, Ann Arbor, Michigan, USA. btarini@umich.edu
authors.forename: Beth A
authors.initials: BA
authors.lastname: Tarini
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Garrison
authors.forename: Dimitri A
authors.initials: DA
authors.lastname: Christakis
mesh_terms: D000704:Analysis of Variance; D001772:Blood Cell Count / Q000191:economics; D001988:Bronchiolitis / Q000097:blood* / Q000191:economics; D016009:Chi-Square Distribution; D002673:Child, Hospitalized; D003365:Costs and Cost Analysis; D005260:Female; D017722:Hospital Charges; D006801:Humans; D007223:Infant; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D014481:United States