|Titre :||Validation of self-reported cannabis dose and potency: an ecological study (2013)|
|Auteurs :||P. VAN DER POL ; N. LIEBREGTS ; R. DE GRAAF ; D. J. KORF ; W. VAN DEN BRINK ; M. VAN LAAR|
|Type de document :||Article : Périodique|
|Dans :||Addiction (Vol.108, n°10, October 2013)|
|Article en page(s) :||1801-1808|
|Discipline :||EPI (Epidémiologie / Epidemiology)|
Thésaurus TOXIBASECANNABIS ; TETRAHYDROCANNABINOL ; AUTOEVALUATION ; FIABILITE ; VALIDITE ; CONSOMMATION ; ADULTE ; USAGE REGULIER
Aims: To assess the reliability and validity of self-reported cannabis dose and potency measures.
Design: Cross-sectional study comparing self-reports with objective measures of amount of cannabis and delta-9-tetrahydrocannabinol (THC) concentration.
Setting: Ecological study with assessments at participants' homes or in a coffee shop.
Participants: Young adult frequent cannabis users (n = 106) from the Dutch Cannabis Dependence (CanDep) study.
Measurements: The objectively measured amount of cannabis per joint (dose in grams) was compared with self-reported estimates using a prompt card and average number of joints made from 1 g of cannabis. In addition, objectively assessed THC concentration in the participant's cannabis was compared with self-reported level of intoxication, subjective estimate of cannabis potency and price per gram of cannabis.
Findings: Objective estimates of doses per joint (0.07-0.88 g/joint) and cannabis potency (1.1-24.7%) varied widely. Self-reported measures of dose were imprecise, but at group level, average dose per joint was estimated accurately with the number of joints made from 1 g [limit of agreement (LOA) = -0.02 g, 95% confidence interval (CI) = -0.29; 0.26], whereas the prompt card resulted in serious underestimation (LOA = 0.14 g, 95% CI = -0.10; 0.37). THC concentration in cannabis was associated with subjective potency ['average' 3.77% (P = 0.002) and '(very) strong' 5.13% more THC (P Conclusions: Self-report measures relating to cannabis use appear at best to be associated weakly with objective measures. Of the self-report measures, number of joints per gram, cannabis price and subjective potency have at least some validity.
|Domaine :||Drogues illicites / Illicit drugs|
|Refs biblio. :||28|
|Affiliation :||Trimbos Institute, Netherlands Institute of Mental Health and Addiction, Utrecht, the Netherlands|