title: The impact of non-concordant self-report of substance use in clinical trials research.
abstract: BACKGROUND
  Studies comparing self-report substance use data to biochemical verification generally demonstrate high rates of concordance. We argue that these rates are due to the relatively high true negative rate in the general population, and high degree of honestly in treatment seeking individuals. We hypothesized that high risk individuals not seeking treatment would demonstrate low concordance and a high false negative rate of self-reported substance use.
  
  
  METHODS
  A sample of 500 individuals from a smoking cessation clinical trial was assessed over 1 year. Assessments included semi-structured interviews, questionnaires (e.g. Addiction Severity Index, etc.), and urine drug screen assays (UDS). Generalized estimating equations (GEEs) were used to predict false negative reports for various substances across the study and determine the influence of substance use on the primary study outcome of smoking cessation.
  
  
  RESULTS
  Participants demonstrated high false negative rates in reporting substances use, and the false negative rates increased as the study progressed. Established predictors of false negatives generalized to the current sample. High concordance and low false negative rates were found in self-report of nicotine use. A small but significant relationship was found in for effect of biochemically verified substance use on smoking cessation.
  
  
  CONCLUSIONS
  Biochemical verification of substance use is needed in high risk populations involved in studies not directly related to the treatment of substance use, especially in populations with high threat of stigmatization. Testing should continue through the time period of the study for maximal identification of substance use.
authors.affiliation: Wichita State University, Department of Psychology, United States. Electronic address: ac.brendan.clark@wichita.edu.
authors.forename: C Brendan
authors.initials: CB
authors.lastname: Clark
authors.affiliation: University of Alabama at Birmingham, Department of Medicine, United States.
authors.forename: Cosmas M
authors.initials: CM
authors.lastname: Zyambo
authors.affiliation: University of Alabama at Birmingham, Department of Psychiatry and Behavioral Neurobiology, United States.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: University of Alabama at Birmingham, Department of Psychiatry and Behavioral Neurobiology, United States.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Cropsey
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000628:therapy* / Q000652:urine; D002986:Clinical Trials as Topic; D019970:Cocaine-Related Disorders / Q000628:therapy / Q000652:urine; D003367:Cotinine / Q000652:urine; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000628:therapy* / Q000652:urine; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000628:therapy / Q000652:urine; D057566:Self Report; D012907:Smoking / Q000628:therapy* / Q000652:urine; D016540:Smoking Cessation; D015813:Substance Abuse Detection; D019966:Substance-Related Disorders / Q000628:therapy* / Q000652:urine
chemical_list: D003367:Cotinine
keywords: Concordance; Criminal justice; False negatives; Substance use; Urine drug test