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Enhanced cannabis timeline followback (EC-TLFB) : Comprehensive assessment of cannabis use including standard THC units and validation through biological measures
Petrilli, Kat Lawn, Will Lees, Rachel Mokrysz, Claire Borissova, Anya Ofori, Shelan Trinci, Katie dos Santos, Renato Leitch, Harry Soni, Shilpa
Petrilli, Kat
Lawn, Will
Lees, Rachel
Mokrysz, Claire
Borissova, Anya
Ofori, Shelan
Trinci, Katie
dos Santos, Renato
Leitch, Harry
Soni, Shilpa
Abstract
Aims
The aims of this study were to present an enhanced cannabis timeline followback (EC-TLFB) enabling comprehensive assessment of cannabis use measures, including standard tetrahydrocannabinol (THC) units, and to validate these against objectively indexed urinary 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH) concentrations.
Design
We used cross-sectional baseline data from the ‘CannTeen’ observational longitudinal study.
Setting
The study was conducted in London, UK.
Participants
A total of 147 participants who used cannabis regularly took part in the study (n = 71 female, n = 76 male; mean age = 21.90, standard deviation = 5.32).
Measurements
The EC-TLFB was used to calculate frequency of cannabis use, method of administration, including co-administration with tobacco, amount of cannabis used (measured with unaided self-report and also using pictorial aided self-report) and type of cannabis product (flower, hash) which was used to estimate THC concentration (both from published data on THC concentration of products and analysis of cannabis samples donated by participants in this study). We calculated total weekly standard THC units (i.e. 5 mg THC for all cannabis products and methods of administration) using the EC-TLFB. The outcome variable for validation of past week EC-TLFB assessments was creatinine-normalized carboxy-tetrahydrocannabinol (THC-COOH) in urine.
Findings
All measures of cannabis exposure included in this analysis were positively correlated with levels of THC-COOH in urine (r = 0.41–0.52). Standard THC units, calculated with average concentrations of THC in cannabis in the UK and unaided self-report measures of amount of cannabis used in grams showed the strongest correlation with THC-COOH in urine (r = 0.52, 95% bias-corrected and accelerated = 0.26–0.70).
Conclusions
The enhanced cannabis timeline followback (EC-TLFB) can provide a valid assessment of a comprehensive set of cannabis use measures including standard tetrahydrocannabinol units as well as and traditional TLFB assessments (e.g. frequency of use and grams of cannabis use).
Keywords
assessment, cannabis, dose, EC-TLFB, measurement, standardization
Date
2024
Type
Journal article
Journal
Addiction
Book
Volume
119
Issue
4
Page Range
772-783
Article Number
ACU Department
School of Behavioural and Health Sciences
Faculty of Health Sciences
Faculty of Health Sciences
Relation URI
Source URL
Event URL
Open Access Status
Published as ‘gold’ (paid) open access
License
CC BY 4.0
File Access
Open
Notes
© 2023 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.
This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.