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. 2013 Nov 6:4:138.
doi: 10.3389/fpsyt.2013.00138. eCollection 2013.

Statistics on cannabis users skew perceptions of cannabis use

Rachel M Burns  1 , Jonathan P Caulkins, Susan S Everingham, Beau Kilmer
Affiliations

Statistics on cannabis users skew perceptions of cannabis use

Rachel M Burns et al. Front Psychiatry. .

Erratum in

  • Front Psychiatry. 2013;4:180

Abstract

Collecting information about the prevalence of cannabis use is necessary but not sufficient for understanding the size, dynamics, and outcomes associated with cannabis markets. This paper uses two data sets describing cannabis consumption in the United States and Europe to highlight (1) differences in inferences about sub-populations based on the measure used to quantify cannabis-related activity; (2) how different measures of cannabis-related activity can be used to more accurately describe trends in cannabis usage over time; and (3) the correlation between frequency of use in the past-month and average grams consumed per use-day.

Key findings: focusing on days of use instead of prevalence shows substantially greater increases in U.S. cannabis use in recent years; however, the recent increase is mostly among adults, not youth. Relatively more rapid growth in use days also occurred among the college-educated and Hispanics. Further, data from a survey conducted in seven European countries show a strong positive correlation between frequency of use and quantity consumed per day of use, suggesting consumption is even more skewed toward the minority of heavy users than is suggested by days-of-use calculations.

Keywords: cannabis; drug use metrics; drug use trends; marijuana; substance abuse research.

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Figures

Figure 1
Figure 1
The reported number of purchases per day of use varies dramatically with age in U.S. household survey data, 2011 NSDUH.
Figure 2
Figure 2
Past-month use-days and daily near-daily users increased more rapidly from 2002 to 2011 than past-year and past-month users, NSDUH. Note: because NSDUH did not collect data about blunts in 2002 and 2003, use-days may be underestimated for these years.
Figure 3
Figure 3
Daily/near-daily users (21 days or more in the past-month) represent a minority of users yet are responsible for the majority of past-month use-days. Note: because NSDUH did not collect data about blunts in 2002 and 2003, use-days may be underestimated for these years.
Figure 4
Figure 4
Age distribution of daily near-daily cannabis users shifts over time so that older adults are responsible for an increasing proportion of consumption. Note: because NSDUH did not collect data about blunts in 2002 and 2003, use-days may be underestimated for these years.
Figure 5
Figure 5
Past-month use-days among older adults (50 and over) increased dramatically over this 10-year time period while use-days among youth (12–17) remained fairly stable. Note: because NSDUH did not collect data about blunts in 2002 and 2003, use-days may be underestimated for these years.
Figure 6
Figure 6
A greater proportion of cannabis, alcohol, cigarettes, and cocaine use-days are attributable to older adults in 2011. Note: because NSDUH did not collect data about blunts in 2002 and 2003, cannabis use-days may be underestimated for these years.
Figure 7
Figure 7
Average quantity of cannabis consumed per day increases with frequency of cannabis use.
Figure 8
Figure 8
The number of 1 day per month users required to match usage of more frequent users is higher when measuring usage in terms of grams per month rather than past-month use-days.
See this image and copyright information in PMC

References

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