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Validation of self-reported cannabis dose and potency: an ecological study.
Addiction. 2013 Oct; 108(10):1801-8.A

Abstract

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 < 0.001) than '(very) mild' cannabis] and with cannabis price (about 1% increase in THC concentration per euro spent on 1 g of cannabis, P < 0.001), but not with level of intoxication.

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.

Authors+Show Affiliations

Trimbos Institute, Netherlands Institute of Mental Health and Addiction, Utrecht, the Netherlands.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Validation Study

Language

eng

PubMed ID

23627816

Citation

van der Pol, Peggy, et al. "Validation of Self-reported Cannabis Dose and Potency: an Ecological Study." Addiction (Abingdon, England), vol. 108, no. 10, 2013, pp. 1801-8.
van der Pol P, Liebregts N, de Graaf R, et al. Validation of self-reported cannabis dose and potency: an ecological study. Addiction. 2013;108(10):1801-8.
van der Pol, P., Liebregts, N., de Graaf, R., Korf, D. J., van den Brink, W., & van Laar, M. (2013). Validation of self-reported cannabis dose and potency: an ecological study. Addiction (Abingdon, England), 108(10), 1801-8. https://doi.org/10.1111/add.12226
van der Pol P, et al. Validation of Self-reported Cannabis Dose and Potency: an Ecological Study. Addiction. 2013;108(10):1801-8. PubMed PMID: 23627816.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Validation of self-reported cannabis dose and potency: an ecological study. AU - van der Pol,Peggy, AU - Liebregts,Nienke, AU - de Graaf,Ron, AU - Korf,Dirk J, AU - van den Brink,Wim, AU - van Laar,Margriet, Y1 - 2013/05/30/ PY - 2012/10/15/received PY - 2012/12/20/revised PY - 2013/04/19/accepted PY - 2013/5/1/entrez PY - 2013/5/1/pubmed PY - 2014/5/3/medline KW - Dose KW - THC KW - potency KW - quantity KW - self-report KW - validation SP - 1801 EP - 8 JF - Addiction (Abingdon, England) JO - Addiction VL - 108 IS - 10 N2 - 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 < 0.001) than '(very) mild' cannabis] and with cannabis price (about 1% increase in THC concentration per euro spent on 1 g of cannabis, P < 0.001), but not with level of intoxication. 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. SN - 1360-0443 UR - https://www.unboundmedicine.com/medline/citation/23627816/Validation_of_self_reported_cannabis_dose_and_potency:_an_ecological_study_ L2 - https://doi.org/10.1111/add.12226 DB - PRIME DP - Unbound Medicine ER -