title: The accuracy of self-reported data concerning recent cannabis use in the French armed forces.
abstract: BACKGROUND
  The aims were to evaluate the accuracy of self-report of past-month cannabis use in a representative sample of French military staff members and to evaluate the scale of the prevarication bias.
  
  
  METHODS
  Data from three cross-sectional surveys conducted between 2005 and 2008 (n = 3493) were used. The characteristics of self-report (sensitivity, specificity, positive predictive value and negative predictive value) were computed using tetrahydrocannabinol detection in urine as the reference.
  
  
  RESULTS
  The prevalence for past-month cannabis use was 16.1% and for positive testing was 13.4%. The discriminant power of self-report was good, with an area under the receiver operating characteristics curve 0.90. Specificity (94.5%) and negative predictive values (97.8%) were good, but sensitivity (85.7%) and positive predictive values (70.4%) were lower. The lowest sensitivity values were observed in the higher categories of personnel and in the Navy, which could reflect some prevarication in these sub-populations who might believe they were more exposed to sanctions if detected.
  
  
  CONCLUSIONS
  Despite certain limitations of urine analysis as a reference, because of its poor detection of occasional users, our study is in favour of good accuracy of self-reported data on cannabis use, even among the military. However, our results, derived from a population study, do not enable any assumptions on the validity of self-reported data collected during individual testing procedures for the purpose of improving occupational safety.
authors.affiliation: Centre d'Épidémiologie et de Santé Publique des Armées, Ministére de la Défense / Service de Santé des Armées, Saint Mandé, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Mayet
authors.forename: Maxime
authors.initials: M
authors.lastname: Esvan
authors.forename: Catherine
authors.initials: C
authors.lastname: Marimoutou
authors.forename: Rachel
authors.initials: R
authors.lastname: Haus-Cheymol
authors.forename: Catherine
authors.initials: C
authors.lastname: Verret
authors.forename: Lénaïck
authors.initials: L
authors.lastname: Ollivier
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Meynard
authors.forename: Rémy
authors.initials: R
authors.lastname: Michel
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Boutin
authors.forename: Xavier
authors.initials: X
authors.lastname: Deparis
authors.forename: René
authors.initials: R
authors.lastname: Migliani
mesh_terms: D000328:Adult; D002188:Cannabis; D003430:Cross-Sectional Studies; D013759:Dronabinol / Q000652:urine; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology / Q000652:urine*; D008889:Military Personnel; D015995:Prevalence; D015203:Reproducibility of Results; D012650:Self Disclosure; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D016482:Urinalysis
chemical_list: D013759:Dronabinol