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Citation
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González-Roz A, Martínez-Loredo V, Aston ER, Metrik J, Murphy J, Balodis I, Secades-Villa R, Belisario K, Mackillop J. Addiction 2022; ePub(ePub): ePub. |
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Abstract
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BACKGROUND AND AIMS: The Marijuana Purchase Task (MPT) is increasingly used to measure cannabis reinforcing value and has potential utility 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(max) (i.e., maximum consumption), P(max) (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= 4,077, median % females: 44.8%: weighted average age= 29.08 (SD: 6.82)], published between 2015-2022. Intensity, O(max) and elasticity showed the most robust concurrent validity [|r's|=.147-325, ps <.014] with the largest significant effect sizes for quantity [|r| intensity=.325] and cannabis dependence [|r|O(max) =.320,|r|intensity=.305,|r|elasticity=.303]. Higher proportion of males was associated with increased estimates for elasticity-quantity, and P(max) -problems. Higher number of MPT prices significantly altered magnitude of effects sizes for P(max) 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 appears to have concurrent validity to quantify cannabis demand, most robustly for intensity, O(max) and elasticity. Moderating effects by sex suggest potentially meaningful sex differences in the reinforcing value of cannabis.
Language: en |