title: The utility of collateral student drinking reports: Evidence from a biomarker study.
abstract: BACKGROUND
  Researchers have increasingly used collateral informants to validate the reports provided by primary research subjects. We assessed the utility of collateral informants for college students in a study that incorporates biomarkers to validate student reports of recent drinking behavior.
  
  
  METHODS
  Students from a Midwestern university were randomly selected for a study in which they provided 90-day Timeline Followback data, hair and fingernail specimens for ethylglucuronide (EtG) testing, and information about collateral (friends or peers) informants who were familiar with their drinking behavior. We compared summary measures of recent drinking to collateral informant reports for the subset of 72 students who were selected to participate in the collateral validation process who had complete measures. Kappa, weighted kappa, and McNemar tests were performed to evaluate levels of agreement. We compared levels of use indicated by each informant within the context of EtG findings. We also compared respondent and collateral reports with respect to heavy drinking directly to EtG test results.
  
  
  RESULTS
  There was considerable overlap between the reports provided by the student participants and their collateral informants. Within the context of EtG-informed analyses, collaterals rarely provided new information about heavy use beyond that provided by the study subjects.
  
  
  CONCLUSIONS
  Collateral informants have limited utility in non-clinical studies of heavy drinking in randomly selected college students.
authors.affiliation: School of Social Work University of Connecticut West Hartford, Connecticut USA. Electronic address: michael.fendrich@uconn.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Fendrich
authors.affiliation: Center for Applied Behavioral Health Research University of Wisconsin-Milwaukee Milwaukee, Wisconsin USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fuhrmann
authors.affiliation: Center for Applied Behavioral Health Research University of Wisconsin-Milwaukee Milwaukee, Wisconsin USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Berger
authors.affiliation: United States Drug Testing Laboratories, Inc. Des Plaines, Illinois USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Plate
authors.affiliation: United States Drug Testing Laboratories, Inc. Des Plaines, Illinois USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Lewis
authors.affiliation: United States Drug Testing Laboratories, Inc. Des Plaines, Illinois USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Jones
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology / Q000378:metabolism*; D000067292:Alcohol Drinking in College; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D005965:Glucuronates / Q000378:metabolism; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013334:Students / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D005965:Glucuronates; C093924:ethyl glucuronide
keywords: Biomarker; Collateral; College students; Drinking; Validity