Publications by authors named "Greg Midgette"

7 Publications

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Heroin use cannot be measured adequately with a general population survey.

Addiction 2021 Mar 2. Epub 2021 Mar 2.

University of Maryland, Department of Criminology and Criminal Justice, College Park, MD, USA.

Background: Globally, heroin and other opioids account for more than half of deaths and years-of-life-lost due to drug use and comprise one of the four major markets for illegal drugs. Having sound estimates of the number of problematic heroin users is fundamental to formulating sound health and criminal justice policies. Researchers and policymakers rely heavily upon general population surveys (GPS), such as the US National Survey on Drug Use and Health (NSDUH), to estimate heroin use, without confronting their limitations. GPS-based estimates are also ubiquitous for cocaine and methamphetamine, so insights pertaining to GPS for estimating heroin use are also relevant for those drug markets.

Analysis: Four sources of potential errors in NSDUH are assessed: selective non-response, small sample size, sampling frame omissions and under-reporting. An alternative estimate drawing on a variety of sources including a survey of adult male arrestees is presented and explained. Other approaches to prevalence estimation are discussed.

Findings: Under-reporting and selective non-response in NSDUH are likely to lead to substantial underestimation. Small sample size leads to imprecise estimates and erratic year-to-year fluctuations. The alternative estimate provides credible evidence that NSDUH underestimates the number of frequent heroin users by at least three-quarters and perhaps much more.

Implications: GPS, even those as strong as NSDUH, are doomed by their nature to estimate poorly a rare and stigmatized behavior concentrated in a hard-to-track population. Although many European nations avoid reliance upon these surveys, many others follow the US model. Better estimation requires models that draw upon a variety of data sources, including GPS, to provide credible estimates. Recent methodological developments in selected countries can provide guidance. Journals should require researchers to critically assess the soundness of GPS estimates for any stigmatized drug-related behaviors with low prevalence rates.
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March 2021

Has Cannabis Use Among Youth Increased After Changes in Its Legal Status? A Commentary on Use of Monitoring the Future for Analyses of Changes in State Cannabis Laws.

Prev Sci 2020 01;21(1):137-145

Department of Criminology & Criminal Justice, University of Maryland, 2220 LeFrak Hall, College Park, MD, USA.

As US states move toward various forms of adult access to cannabis, there has been a great interest in measuring the impact of such changes on adolescent cannabis use. Two recent prominent analyses have used Monitoring the Future (MTF), a nationally representative survey of students, to examine the effects. We compared MTF data for California and for Washington State with other survey data on use by adolescents in those states. In both studies, findings based on MTF were different from those using other larger, state-representative surveys. The discrepancy reflects the high within-state variation in prevalence rates and the small number of schools in MTF state samples. Using the Washington Health Youth Survey, we estimate that after recreational cannabis legalization past 30-day cannabis use prevalence in grade 8 decreased by 22.0%, in grade 10 prevalence decreased by 12.7%, and no effect in grade 12. These trends are consistent with those in states without recreational cannabis laws, suggesting that legalization did not impact adolescent use prevalence. Long-term trends in MTF are consistent with other data, but year-to-year volatility in state-level series undermines the survey's suitability for evaluation of state cannabis policy changes. Survey-based analyses at the state level need to be cross-validated with findings from other data sources. When findings are disparate and methodological rigor is equivalent, analyses of data sources specifically designed to describe state-level phenomena are more credible.
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January 2020

Variation in cannabis potency and prices in a newly legal market: evidence from 30 million cannabis sales in Washington state.

Addiction 2017 Dec 4;112(12):2167-2177. Epub 2017 Jul 4.

RAND Corporation, Santa Monica, CA, USA.

Aims: To (1) assess trends and variation in the market share of product types and potency sold in a legal cannabis retail market and (2) estimate how potency and purchase quantity influence price variation for cannabis flower.

Design: Secondary analysis of publicly available data from Washington State's cannabis traceability system spanning 7 July 2014 to 30 September 2016. Descriptive statistics and linear regressions assessed variation and trends in cannabis product variety and potency. Hedonic regressions estimated how purchase quantity and potency influence cannabis flower price variation.

Setting: Washington State, USA.

Participants: (1) A total of 44 482 176 million cannabis purchases, including (2) 31 052 123 cannabis flower purchases after trimming price and quantity outliers.

Measurements: Primary outcome measures were (1) monthly expenditures on cannabis, total delta-9-tetrahydrocannabinol (THC) concentration and cannabidiol (CBD) concentration by product type and (2) excise tax-inclusive price per gram of cannabis flower. Key covariates for the hedonic price regressions included quantity purchased, THC and CBD.

Findings: Traditional cannabis flowers still account for the majority of spending (66.6%), but the market share of extracts for inhalation increased by 145.8% between October 2014 and September 2016, now comprising 21.2% of sales. The average THC-level for cannabis extracts is more than triple that for cannabis flowers (68.7% compared to 20.6%). For flower products, there is a statistically significant relationship between price per gram and both THC [coefficient = 0.012; 95% confidence interval (CI) = 0.011-0.013] and CBD (coefficient = 0.017; CI = 0.015-0.019). The estimated discount elasticity is -0.06 (CI = -0.07 to -0.05).

Conclusions: In the state of Washington, USA, the legal cannabis market is currently dominated by high-THC cannabis flower, and features growing expenditures on extracts. For cannabis flower, both THC and CBD are associated with higher per-gram prices, and there are small but significant quantity discounts.
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December 2017

Cocaine's fall and marijuana's rise: questions and insights based on new estimates of consumption and expenditures in US drug markets.

Addiction 2015 May 14;110(5):728-36. Epub 2014 Jul 14.

Heinz College, Carnegie Mellon University, Pittsburgh, PA, USA; RAND Drug Policy Research Center, RAND, Santa Monica, CA, USA.

Aims: Drug policy strategies and discussions often use prevalence of drug use as a primary performance indicator. However, three other indicators are at least as relevant: the number of heavy users, total expenditures and total amount consumed. This paper stems from our efforts to develop annual estimates of these three measures for cocaine (including crack), heroin, marijuana and methamphetamine in the United States.

Methods: The estimates exploit complementary strengths of a general population survey (National Survey on Drug Use and Health) and both survey and urinalysis test result data for arrestees (Arrestee Drug Abuse Monitoring Program), supplemented by many other data sources.

Results: Throughout the 2000s US drug users spent in the order of $100 billion annually on these drugs, although the spending distribution and use patterns changed dramatically. From 2006 to 2010, the amount of marijuana consumed in the United States probably increased by more than 30%, while the amount of cocaine consumed in the United States fell by approximately 50%. These figures are consistent with supply-side indicators, such as seizures and production estimates. For all the drugs, total consumption and expenditures are driven by the minority of users who consume on 21 or more days each month.

Conclusions: Even for established drugs, consumption can change rapidly. The halving of the cocaine market in five years and the parallel (but independent) large rise in daily/near-daily marijuana use are major events that were not anticipated by the expert community and raise important theoretical, research, and policy issues.
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May 2015

The whole is just the sum of its parts: limited polydrug use among the "big three" expensive drugs in the United States.

Curr Drug Abuse Rev 2013 Jun;6(2):91-7

Carnegie Mellon University, Heinz College, 5000 Forbes Ave., Pittsburgh, PA 15213, USA.

Data from surveys of arrestees and the household population in the U.S. suggest there is only modest overlap among demand for the big three expensive illegal drugs (cocaine/crack, heroin, and methamphetamine). In particular, the number of chronic users of these substances (defined as consuming on four or more days in the previous month) is only about 10% below a naïve estimate obtained by simply summing the numbers of chronic users for each of the three substances, while ignoring polydrug use entirely. This finding does not gainsay that polydrug use is common or important. One would estimate greater overlap if one adopted a more expansive definition of polydrug use (e.g., has the individual ever used another substance at any time in their life) or a more expansive list of substances (e.g., allowing marijuana or alcohol to count as one of the substances makes polydrug use seem much more common). However, it does suggest that when focusing on the illegal drug markets that generate the most crime, violence, and overdose death in the U.S., one can usefully think of three more or less separate markets populated at any given time by largely distinct populations of drug users.
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June 2013

Efficacy of frequent monitoring with swift, certain, and modest sanctions for violations: insights from South Dakota's 24/7 Sobriety Project.

Am J Public Health 2013 Jan 15;103(1):e37-43. Epub 2012 Nov 15.

RAND Corporation, Santa Monica, CA 90401, USA.

Objectives: We examined the public health impact of South Dakota's 24/7 Sobriety Project, an innovative program requiring individuals arrested for or convicted of alcohol-involved offenses to submit to breathalyzer tests twice per day or wear a continuous alcohol monitoring bracelet. Those testing positive are subject to swift, certain, and modest sanctions.

Methods: We conducted differences-in-differences analyses comparing changes in arrests for driving while under the influence of alcohol (DUI), arrests for domestic violence, and traffic crashes in counties to the program with counties without the program.

Results: Between 2005 and 2010, more than 17,000 residents of South Dakota-including more than 10% of men aged 18 to 40 years in some counties-had participated in the 24/7 program. At the county level, we documented a 12% reduction in repeat DUI arrests (P = .023) and a 9% reduction in domestic violence arrests (P = .035) following adoption of the program. Evidence for traffic crashes was mixed.

Conclusions: In community supervision settings, frequent alcohol testing with swift, certain, and modest sanctions for violations can reduce problem drinking and improve public health outcomes.
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January 2013