Abstract
Background and aims
Currently, there is no data-driven cannabis reduction metric using biochemical verification, which represents a significant gap in cannabis harm reduction research, treatment and policy. Using aggregated data from 7 cannabis use disorder treatment trials, the aims of this analysis were to 1) determine if decreases in self-reported cannabis use correlate with a decrease in urinary cannabinoids and 2) determine the cut-off in reduction of creatinine-normalized cannabinoids (CN:THC) associated with self-reported cannabis use reduction.
Design
Exploratory aggregated analysis of 7 cannabis use disorder treatment trials.
Setting
Individual studies were conducted in academic medical centers and community substance use treatment settings in the United States and led by investigators at the Medical University of South Carolina.
Participants
Participants were included who had cannabis use data available through week 6 of study treatment and did not meet criteria for continuous cannabis abstinence (n = 471/920; 51%; analytic sample was 31% female; 67% White; 11% Hispanic; mean age of 25).
Measurements
Weekly self-reported cannabis use (days of use, sessions or grams of use per day, collected via daily diaries or timeline follow-back) and urinary cannabinoids [tetrahydrocannabinol (THC) metabolites; ng/ml]. The sample was categorized as 1) reduced self-reported cannabis use (50% reduction in frequency and/or 75% in amount; n = 220) or 2) no self-reported cannabis reduction (n = 251). Longitudinal models included indicators for reduction group, parent study, study week, baseline urinary cannabinoids and covariates (age, race, years of cannabis use) statistically significantly associated with study outcomes.
Findings
Participants self-reporting cannabis use reduction had statistically significantly lower urinary cannabinoids compared with those who did not reduce [Δ between groups = 391 ng/ml; 95% confidence interval (CI) = 231–551; P < 0.001]. Average urinary cannabinoids decreased by up to 50% from baseline levels for the cannabis reduction group. The classification model for decrease in urinary CN:THC did not produce a cut-point statistically significantly different from zero (−39.9; 95% CI = −70.3 to 2.9).
Conclusions
Average urinary cannabinoids, measuring THC, during cannabis use disorder treatment trials appear to differ between participants with and without self-reported cannabis use reduction. Urinary cannabinoids appear to decrease concurrently with self-reported use reduction, with a 50% average decrease being observed among those self-reporting reductions. Overall classification models did not yield a urinary creatinine-normalized cannabinoids cut-off that could be used for individuals to detect meaningful cannabis reduction. Individual-based biochemical verification of cannabis reduction will require further work to establish, though average reductions of at least 50% in urinary cannabinoids may be a useful metric for the majority of those with cannabis use disorder in clinical and research settings.