Medical marijuana laws and adolescent marijuana use in the United States

a systematic review and meta-analysis

Aaron L. Sarvet, Melanie M. Wall, David S. Fink, Emily Greene, Aline Le, Anne E. Boustead, Rosalie Liccardo Pacula, Katherine M. Keyes, Magdalena Cerda, Sandro Galea, Deborah S. Hasin

Research output: Contribution to journalReview article

32 Citations (Scopus)

Abstract

Aims: To conduct a systematic review and meta-analysis of studies in order to estimate the effect of US medical marijuana laws (MMLs) on past-month marijuana use prevalence among adolescents. Methods: A total of 2999 papers from 17 literature sources were screened systematically. Eleven studies, developed from four ongoing large national surveys, were meta-analyzed. Estimates of MML effects on any past-month marijuana use prevalence from included studies were obtained from comparisons of pre–post MML changes in MML states to changes in non-MML states over comparable time-periods. These estimates were standardized and entered into a meta-analysis model with fixed-effects for each study. Heterogeneity among the study estimates by national data survey was tested with an omnibus F-test. Estimates of effects on additional marijuana outcomes, of MML provisions (e.g. dispensaries) and among demographic subgroups were abstracted and summarized. Key methodological and modeling characteristics were also described. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Results: None of the 11 studies found significant estimates of pre–post MML changes compared with contemporaneous changes in non-MML states for marijuana use prevalence among adolescents. The meta-analysis yielded a non-significant pooled estimate (standardized mean difference) of −0.003 (95% confidence interval = −0.012, +0.007). Four studies compared MML with non-MML states on pre-MML differences and all found higher rates of past-month marijuana use in MML states pre-MML passage. Additional tests of specific MML provisions, of MML effects on additional marijuana outcomes and among subgroups generally yielded non-significant results, although limited heterogeneity may warrant further study. Conclusions: Synthesis of the current evidence does not support the hypothesis that US medical marijuana laws (MMLs) until 2014 have led to increases in adolescent marijuana use prevalence. Limited heterogeneity exists among estimates of effects of MMLs on other patterns of marijuana use, of effects within particular population subgroups and of effects of specific MML provisions.

Original languageEnglish (US)
Pages (from-to)1003-1016
Number of pages14
JournalAddiction
Volume113
Issue number6
DOIs
StatePublished - Jun 1 2018

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Medical Marijuana
Cannabis
Meta-Analysis

Keywords

  • Adolescent
  • epidemiology
  • marijuana
  • meta-analysis
  • policy
  • systematic review

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Psychiatry and Mental health

Cite this

Sarvet, A. L., Wall, M. M., Fink, D. S., Greene, E., Le, A., Boustead, A. E., ... Hasin, D. S. (2018). Medical marijuana laws and adolescent marijuana use in the United States: a systematic review and meta-analysis. Addiction, 113(6), 1003-1016. https://doi.org/10.1111/add.14136

Medical marijuana laws and adolescent marijuana use in the United States : a systematic review and meta-analysis. / Sarvet, Aaron L.; Wall, Melanie M.; Fink, David S.; Greene, Emily; Le, Aline; Boustead, Anne E.; Pacula, Rosalie Liccardo; Keyes, Katherine M.; Cerda, Magdalena; Galea, Sandro; Hasin, Deborah S.

In: Addiction, Vol. 113, No. 6, 01.06.2018, p. 1003-1016.

Research output: Contribution to journalReview article

Sarvet, AL, Wall, MM, Fink, DS, Greene, E, Le, A, Boustead, AE, Pacula, RL, Keyes, KM, Cerda, M, Galea, S & Hasin, DS 2018, 'Medical marijuana laws and adolescent marijuana use in the United States: a systematic review and meta-analysis', Addiction, vol. 113, no. 6, pp. 1003-1016. https://doi.org/10.1111/add.14136
Sarvet, Aaron L. ; Wall, Melanie M. ; Fink, David S. ; Greene, Emily ; Le, Aline ; Boustead, Anne E. ; Pacula, Rosalie Liccardo ; Keyes, Katherine M. ; Cerda, Magdalena ; Galea, Sandro ; Hasin, Deborah S. / Medical marijuana laws and adolescent marijuana use in the United States : a systematic review and meta-analysis. In: Addiction. 2018 ; Vol. 113, No. 6. pp. 1003-1016.
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abstract = "Aims: To conduct a systematic review and meta-analysis of studies in order to estimate the effect of US medical marijuana laws (MMLs) on past-month marijuana use prevalence among adolescents. Methods: A total of 2999 papers from 17 literature sources were screened systematically. Eleven studies, developed from four ongoing large national surveys, were meta-analyzed. Estimates of MML effects on any past-month marijuana use prevalence from included studies were obtained from comparisons of pre–post MML changes in MML states to changes in non-MML states over comparable time-periods. These estimates were standardized and entered into a meta-analysis model with fixed-effects for each study. Heterogeneity among the study estimates by national data survey was tested with an omnibus F-test. Estimates of effects on additional marijuana outcomes, of MML provisions (e.g. dispensaries) and among demographic subgroups were abstracted and summarized. Key methodological and modeling characteristics were also described. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Results: None of the 11 studies found significant estimates of pre–post MML changes compared with contemporaneous changes in non-MML states for marijuana use prevalence among adolescents. The meta-analysis yielded a non-significant pooled estimate (standardized mean difference) of −0.003 (95{\%} confidence interval = −0.012, +0.007). Four studies compared MML with non-MML states on pre-MML differences and all found higher rates of past-month marijuana use in MML states pre-MML passage. Additional tests of specific MML provisions, of MML effects on additional marijuana outcomes and among subgroups generally yielded non-significant results, although limited heterogeneity may warrant further study. Conclusions: Synthesis of the current evidence does not support the hypothesis that US medical marijuana laws (MMLs) until 2014 have led to increases in adolescent marijuana use prevalence. Limited heterogeneity exists among estimates of effects of MMLs on other patterns of marijuana use, of effects within particular population subgroups and of effects of specific MML provisions.",
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AU - Le, Aline

AU - Boustead, Anne E.

AU - Pacula, Rosalie Liccardo

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N2 - Aims: To conduct a systematic review and meta-analysis of studies in order to estimate the effect of US medical marijuana laws (MMLs) on past-month marijuana use prevalence among adolescents. Methods: A total of 2999 papers from 17 literature sources were screened systematically. Eleven studies, developed from four ongoing large national surveys, were meta-analyzed. Estimates of MML effects on any past-month marijuana use prevalence from included studies were obtained from comparisons of pre–post MML changes in MML states to changes in non-MML states over comparable time-periods. These estimates were standardized and entered into a meta-analysis model with fixed-effects for each study. Heterogeneity among the study estimates by national data survey was tested with an omnibus F-test. Estimates of effects on additional marijuana outcomes, of MML provisions (e.g. dispensaries) and among demographic subgroups were abstracted and summarized. Key methodological and modeling characteristics were also described. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Results: None of the 11 studies found significant estimates of pre–post MML changes compared with contemporaneous changes in non-MML states for marijuana use prevalence among adolescents. The meta-analysis yielded a non-significant pooled estimate (standardized mean difference) of −0.003 (95% confidence interval = −0.012, +0.007). Four studies compared MML with non-MML states on pre-MML differences and all found higher rates of past-month marijuana use in MML states pre-MML passage. Additional tests of specific MML provisions, of MML effects on additional marijuana outcomes and among subgroups generally yielded non-significant results, although limited heterogeneity may warrant further study. Conclusions: Synthesis of the current evidence does not support the hypothesis that US medical marijuana laws (MMLs) until 2014 have led to increases in adolescent marijuana use prevalence. Limited heterogeneity exists among estimates of effects of MMLs on other patterns of marijuana use, of effects within particular population subgroups and of effects of specific MML provisions.

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