3-Year Follow-up of Lower Risk Cannabis Use Patterns: Evidence from a Longitudinal Survey

Life-course Accumulated Cannabis Use and Recent Cannabis-related Problems in the Washington Panel Survey

BACKGROUND

Previous studies have only investigated the short-term association of recent cannabis use with cannabis-related problems, without accounting for the onset, duration, and variations in frequency of use in the life-course.

METHODS

We obtained data from the Washington panel survey during 2014-2016. We constructed accumulated lifetime exposure to cannabis use, heavy drinking (5+ drinks on one occasion), and cigarette pack-years from age of onset based on a series of decades-based questions on cannabis use and heavy drinking, and tobacco use history. We used Generalized Estimating Equation with Poisson distribution to investigate the association between accumulated cannabis use and the past-6-month CUDIT score. We adjusted for accumulated heavy drinking and cigarette pack-years, substance co-use variables, demographics, and applied survey weights.

RESULTS

We found strong and statistically significant correlations for the lifetime measures across the four panel surveys, indicating that the life-course measures of cannabis use and heavy drinking were largely reliable. We found a statistically significant relationship between the lifetime accumulated exposure to cannabis and CUDIT. The results were robust to the inconsistencies in reported frequencies and onset age across panel surveys.

CONCLUSIONS

This study established the relationship between lifetime exposure to cannabis and cannabis-related problems in a representative sample of drinkers and marijuana users in Washington state. We have also provided test-retest validity and question details for the decades-based cannabis and heavy drinking measures to facilitate their use in future studies of cannabis and alcohol-related outcomes.

Associations between simultaneous use of alcohol and cannabis and cannabis-related problems in 2014-2016: evidence from the Washington panel survey

BACKGROUND

To address the research question of how simultaneous users of alcohol and cannabis differ from concurrent users in risk of cannabis use problems after the recreational marijuana legalization in Washington State.

METHODS

We used generalized estimating equations with a Poisson distribution to analyze the association between simultaneous use of alcohol and marijuana (SAM) and cannabis-related problems compared to concurrent use. The data is a longitudinal sample of drinkers and cannabis users (n = 257, 47% female) aged 18 years and older from Washington State in 2014-2016. We adjusted for survey weights to account for differential probability of selection and response rates. The primary outcome is the past-six-month CUDIT problem subscale (ranging from 0 to 28), which is the total score for seven CUDIT problem items, after excluding the three items that covered marijuana use frequency. Covariates include marijuana use frequency (daily/near daily use, regular use, or infrequent use), marijuana daily quantity, alcohol daily volume, panel survey cycle, medical marijuana recommendation, driving time to nearest marijuana outlet, age of marijuana use onset, and other demographics.

RESULTS

After adjusting for covariates, we found that compared to concurrent use, SAM was significantly positively associated with CUDIT problem subscale (IRR = 1.68, 95% CI: 1.25-2.27, p < 0.001); daily/near daily use of marijuana was strongly significantly associated with CUDIT problem subscale compared with infrequent use (IRR = 5.1, 2.71-9.57, p < 0.001) or regular use (IRR = 3.05, 1.91-4.85, p < 0.001). Secondary analyses using CUDIT total score as the outcome also showed a significant positive association with SAM compared to concurrent use (IRR = 1.17, 1.02-1.34, p < 0.05).

CONCLUSIONS

This study highlighted the importance of SAM, in addition to cannabis use frequency for predicting cannabis-related problems.

Measuring cannabis quantities in online surveys: A rapid review and proposals for ways forward

OBJECTIVES

Cannabis use quantities are relevant for determining cannabis-related harms. This research aims to provide an overview of the available methods to assess quantities through self-report.

METHODS

A rapid review of various strategies to collect information on cannabis use quantities through self-report. Two independent literature searches resulted in n = 38 studies included for review.

RESULTS

A total of n = 14 studies employed methods for collecting cannabis use quantities that are not suitable for online surveys (e.g., rolling a fake joint). Of the remaining n = 24 studies with items that are suitable for online surveys, the quantity assessment was performed in three different ways. The data collection was either carried out by asking (a) for the total number of joints (i.e., crude joint method), (b) for the total weight (i.e., crude weight method), or (c) for specific products separately, for example, for the amount of flower and resin (i.e., product-specific method). In only n = 8 studies, cannabis use quantities were ascertained by providing visual aids (e.g., illustration of various amounts of flower).

CONCLUSIONS

The crude joint method and the product-specific method are the two most promising methods to collect information on cannabis use quantities. Using visual aids may potentially improve the accuracy of those methods.