Home > Concurrent validity of the marijuana purchase task: a meta-analysis of trait-level cannabis demand and cannabis involvement.

González-Roz, Alba and Martínez-Loredo, Víctor and Aston, Elizabeth R and Metrik, Jane and Murphy, James and Balodis, Iris and Secades-Villa, Roberto and Belisario, Kyla and MacKillop, James (2022) Concurrent validity of the marijuana purchase task: a meta-analysis of trait-level cannabis demand and cannabis involvement. Addiction, 118, (4), pp. 620-633. doi: 10.1111/add.16075.

External website: https://onlinelibrary.wiley.com/doi/10.1111/add.16...

BACKGROUND AND AIMS: The Marijuana Purchase Task (MPT) is increasingly used to measure cannabis reinforcing value and has potential use for cannabis etiological and regulatory research. This meta-analysis sought to evaluate for the first time the MPT's concurrent validity in relation to cannabis involvement.

METHODS: Electronic databases and pre-print repositories were searched for MPT studies that examined the cross-sectional relationship between frequency and quantity of cannabis use, problems, dependence, and five MPT indicators: intensity (i.e. unrestricted consumption), O (i.e. maximum consumption), P (i.e. price at which demand becomes elastic), breakpoint (i.e. first price at which consumption ceases), and elasticity (i.e. sensitivity to rising costs). Random effects meta-analyses of cross-sectional effect sizes were conducted, with Q tests for examining differences by cannabis variables, meta-regression to test quantitative moderators, and publication bias assessment. Moderators included sex, number of MPT prices, variable transformations, and year of publication. Populations included community and clinical samples.

RESULTS: The searches yielded 14 studies (n = 4077, median % females: 44.8%: weighted average age = 29.08 [SD = 6.82]), published between 2015 and 2022. Intensity, O , and elasticity showed the most robust concurrent validity (|r's| = 0.147-325, ps < 0.014) with the largest significant effect sizes for quantity (|r| intensity = 0.325) and cannabis dependence (|r| O  = 0.320, |r| intensity = 0.305, |r| elasticity = 0.303). Higher proportion of males was associated with increased estimates for elasticity-quantity and P -problems. Higher number of MPT prices significantly altered magnitude of effects sizes for P and problems, suggesting biased estimations if excessively low prices are considered. Methodological quality was generally good, and minimal evidence of publication bias was observed.

CONCLUSIONS: The marijuana purchase task presents adequate concurrent validity to measure cannabis demand, most robustly for intensity, O , and elasticity. Moderating effects by sex suggest potentially meaningful sex differences in the reinforcing value of cannabis.

Repository Staff Only: item control page