title: Intercenter differences in bronchopulmonary dysplasia or death among very low birth weight infants.
abstract: OBJECTIVE
  To determine (1) the magnitude of clustering of bronchopulmonary dysplasia (36 weeks) or death (the outcome) across centers of the Eunice Kennedy Shriver National Institute of Child and Human Development National Research Network, (2) the infant-level variables associated with the outcome and estimate their clustering, and (3) the center-specific practices associated with the differences and build predictive models.
  
  
  METHODS
  Data on neonates with a birth weight of <1250 g from the cluster-randomized benchmarking trial were used to determine the magnitude of clustering of the outcome according to alternating logistic regression by using pairwise odds ratio and predictive modeling. Clinical variables associated with the outcome were identified by using multivariate analysis. The magnitude of clustering was then evaluated after correction for infant-level variables. Predictive models were developed by using center-specific and infant-level variables for data from 2001 2004 and projected to 2006.
  
  
  RESULTS
  In 2001-2004, clustering of bronchopulmonary dysplasia/death was significant (pairwise odds ratio: 1.3; P < .001) and increased in 2006 (pairwise odds ratio: 1.6; overall incidence: 52%; range across centers: 32%-74%); center rates were relatively stable over time. Variables that varied according to center and were associated with increased risk of outcome included lower body temperature at NICU admission, use of prophylactic indomethacin, specific drug therapy on day 1, and lack of endotracheal intubation. Center differences remained significant even after correction for clustered variables.
  
  
  CONCLUSIONS
  Bronchopulmonary dysplasia/death rates demonstrated moderate clustering according to center. Clinical variables associated with the outcome were also clustered. Center differences after correction of clustered variables indicate presence of as-yet unmeasured center variables.
authors.affiliation: Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35249, USA. ambal@uab.edu
authors.forename: Namasivayam
authors.initials: N
authors.lastname: Ambalavanan
authors.forename: Michele
authors.initials: M
authors.lastname: Walsh
authors.forename: Georgiy
authors.initials: G
authors.lastname: Bobashev
authors.forename: Abhik
authors.initials: A
authors.lastname: Das
authors.forename: Burton
authors.initials: B
authors.lastname: Levine
authors.forename: Waldemar A
authors.initials: WA
authors.lastname: Carlo
authors.forename: Rosemary D
authors.initials: RD
authors.lastname: Higgins
mesh_terms: D001997:Bronchopulmonary Dysplasia / Q000453:epidemiology* / Q000401:mortality; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D008297:Male; D008962:Models, Theoretical