Spirits purchasing and marijuana use behaviors of risky drinkers in the state of Washington from 2014 to 2016

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.

Characteristics of the Washington cannabis market from 2014 to 2016

BACKGROUND

The state of Washington legalized cannabis for adult use in 2012 and retail stores began to open in 2014. While details of the legal market have been tracked by the state, the total market for cannabis and characteristics of purchasers can only be identified through surveys.

METHODS

Six cross-sectional samples of the Privatization of Spirits in Washington (PSW) surveys were collected between January 2014 and October 2016 with two in each year. Random digit dial procedures were used to recruit a sample aged 18 and older, with 40% of cases from mobile phones. A total of 5492 respondents participated. Analyses of the population-weighted sample utilized purchasing amounts and frequencies, use frequency and related measures to estimate total and mean amounts and expenditures. Sensitivity analyses were conducted for key assumptions.

RESULTS

The market for cannabis flower is estimated to have increased from 158 metric tons and $1.23 billion in 2014 to 222 metric tons and $1.7 billion in 2016, with little change from 2014 to 2015. Purchases from legal sources, retail and dispensaries, were estimated at 69% of the total market. Daily or near daily (DND) users accounted for about 83% of sales in 2014, rising to 91% in 2016. The prevalence of past year use rose substantially from 25% in 2014 to 32% in 2016, with DND use rising from 10.2 to 11.3%. Average purchase amounts for DND users rose from 291 g in 2014 to 374 g in 2016, while mean amounts among non-DND users declined from 78 to 28.6 g.

CONCLUSIONS

The expansion of retail cannabis stores in Washington appears to have led to increased market size in 2016 with all of the increase attributed to DND users. Frequent users may be important to consider in legalization evaluations.

Estimating Usual Grams per Day of Marijuana Use from Purchases

BACKGROUND

Quantifying average amounts of marijuana used per day or per occasion of use helps inform understanding population-level patterns of use and use-related harm, but better estimates and estimation methods are needed. Users have difficulty in reporting use amounts, but purchase amounts may be more clearly recalled.

METHODS

Measures of individual's use and purchasing frequency and details of purchases such as the amounts and products bought and the cost of these were collected in six cross-sectional representative surveys of the population 18 and older in the state of Washington from 2014 to 2016. Analyses utilize purchase information on both flower and other marijuana products to estimate mean amounts per use day and predict use amounts for non-purchasers.

RESULTS

Mean marijuana use per use day among purchasers was 1.35 grams and non-purchasers estimated mean use amount per day was 0.71 grams. Lower mean use per day was a found for women and the most frequent users. Based on these estimates, total past year marijuana use for purchasers had a mean of 184.8 grams and the mean for non-purchasers was 28 grams.

CONCLUSIONS

Methods based on purchasing details can be used to estimate individual's marijuana quantity per occasion and total use amount per year, providing additional outcome measures for analyses of predictors of individual marijuana consumption and facilitating more detailed analyses of risks for marijuana harms.

Price Changes in Washington Following the 2012 Liquor Privatization: An Update Through 2016 With Comparisons to California, Idaho, and Oregon

BACKGROUND

Washington State ended their wholesale and retail monopoly on liquor on June 1, 2012, resulting in a 5-fold increase in liquor outlets in diverse store types. The legislation also included taxes at the wholesale and retail levels. This study seeks to investigate whether prices have changed from 2014 through 2016, as a follow-up to a previous study finding increases in prices from 2012 to 2014, compared to prices in other states.

METHODS

We developed an index of 68 brands that were popular in Washington in early 2012. Data on final liquor prices (including taxes) in Washington and California were obtained through store visits and online sources between November 2013 and March 2014, and again between April and May 2016 for Washington only. Pricing data for Idaho and Oregon were obtained from the Statistics for Alcohol Management Database over both sampling periods. Primary analyses were conducted on the utmost brands available in the majority of the stores sampled.

RESULTS

Liquor prices in Washington rose an average of 3.9% for 750 ml and 6.5% for 1.75-l containers overall from 2014 to 2016, while bordering states Idaho (+2.9%) and Oregon (+1.5%) experienced smaller increases for 750-ml and declines for 1.75-l containers (Idaho: -2.9%, Oregon: -4.9%). In the analyses of spirits prices in Washington compared to California, prices in California were 24.1% lower for 750-ml containers and 29.6% lower for 1.75-l containers.

CONCLUSIONS

Our findings indicate liquor prices in Washington have increased since our 2014 assessment at a larger percentage than prices in the neighboring control states Oregon and Idaho, with varying effects on brands, container sizes, and store types. We demonstrate privatization is associated with a different pattern of prices across store types than seen in California.

Changes in spirits purchasing behaviours after privatisation of government-controlled sales in Washington, USA

INTRODUCTION AND AIMS

The privatisation of the Washington Liquor Monopoly in 2012 offered a unique opportunity to study spirits purchasing behaviour changes from a government to licensed system.

DESIGN AND METHODS

Four representative cross-sectional surveys of adults aged 18 and older in Washington state were recruited between January 2014 and October 2015 (Wave 1, N = 1202; W2, N = 804; W3, N = 823; W4, N = 662). Analyses compared spirits purchasing behaviours before privatisation from retrospective reports to current reports in the areas of travel distance, spirits quality, purchase frequency and size of bottle. Respondents also directly reported on changes in convenience, selection and prices.

RESULTS

No significant changes were found in these aspects of purchasing. However, subgroup analyses found that younger drinkers 18-29 reduced travel distance and increased purchase frequency while drinkers aged 50 and older travelled further. Reduced travel distances were associated with grocery and drug stores while increased travel distances were associated with liquor superstores, wholesale stores and government stores in bordering states. Respondents reported that liquor purchasing was more convenient after privatisation but that the selection of spirits was better and prices were lower in the government-controlled stores.

DISCUSSION AND CONCLUSIONS

The government monopoly stores were viewed as offering a wider selection of products and as having lower prices than those in the privatised system. The variety of store types in the licensed system allowed drinkers to select stores based on convenience, selection or prices, so that travel times increased for some buyers, presumably those seeking lower prices or a wider selection.