Medical Cannabis Program Sustainability in the Era of Recreational Cannabis

Abstract

Purpose:

Since October 2022, a total of 21 states have enacted both medical-use and adult-use cannabis legalization, each with their own unique set of laws, regulations, implementation, structures, and enforcement (“policies”). Unlike adult-use programs, medical-use programs often represent a safer and affordable option for patients with diverse needs; however, current evidence suggests that medical-use program activity decreases after implementation of adult-use retail. The current study compares medical patient registration data and medical- and adult-use retail data from 3 distinct medical- and adult-use states (Colorado, Massachusetts, and Oregon) in the time after adult-use retail implementation in each state.

Methods:

To investigate changes in medical cannabis programs with simultaneous adult-use legalization, correlation and linear regression analyses were used to assess outcome measures: (1) medical-use retail sales; (2) adult-use retail sales; and (3) number of registered medical patients in all fiscal quarters after adult-use retail sales were implemented in each state to September 2022.

Findings:

Adult-use cannabis sales increased significantly over time in all 3 states. However, both medical-use sales and number of medical patients registered in the states increased only in Massachusetts.

Implications:

Results indicate that states’ preexisting medical-use programs may undergo critical changes after adult-use cannabis legalization is enacted and implemented. Key policy and program differences, such as regulatory differences in the implementation of adult-use retail sales, may have differential impacts on medical-use programs. For continued patient access, it is critical that future research assess the differences within and between states’ medical-use and adult-use programs that permit sustainability of medical-use programs alongside adult-use legalization and implementation.

INTRODUCTION

During the past 25 years, many states have acted to both decriminalize and legalize cannabis. In 1996, California enacted the first medical cannabis laws permitting cannabis use for medicinal purposes (“medical-use legalization”). In 2012, Colorado and Washington enacted the first adult-use cannabis laws (“adult-use legalization”).¹ As of October 2022, a total of 37 states, 3 US territories, and Washington, DC, have enacted medical cannabis laws, permitting qualified patients to purchase, possess, and consume cannabis for medical purposes. As of November 2022, twenty-one states, two territories, and Washington, DC, have enacted nonmedical adult-use cannabis laws, allowing adults aged ≥21 years to purchase, possess, and consume cannabis for nonmedical adult-use (“recreational”) purposes. In addition, 10 states have enacted less comprehensive medical-use programs permitting applicable patients to use low tetrahydrocannabinol/high cannabidiol (CBD) products for medical purposes.¹

Due to federal prohibition of cannabis under the Controlled Substance Act of 1970, cannabis legalization in the United States has been a state-led phenomenon, resulting in a heterogeneous patchwork of laws, regulations, implementation, structures, and enforcement (herein collectively referred to as “policies”). There is critical variability across states regarding both medical-use and adult-use legalization policies and programs, although medical-use policies have greater variability in design,^2–4 and programs may undergo important changes as states move to legalize cannabis for adult-use.^5,6 The transition from medical-use policies only to medical- and adult-use cannabis policies warrants careful assessment to understand the changes in medical-use policies and programs after adult-use policy is enacted and implemented.⁵ Any changes to preexisting medical-use programs may affect the safety and protection of patients.

All cannabis policies and programs vary across states; however, there are general key differences between medical- and adult-use cannabis policies and programs that may affect an individual’s purchase, possession, and use behaviors. For example, in some medical cannabis programs, individuals must have a health care provider’s authorization and approval from the state to consume cannabis, whereas adult-use programs permit any individual aged >21 years to consume and/or purchase cannabis. Provisions such as medical provider authorization and medical guidance adds a protective layer for patients to use cannabis safely and effectively for specified illnesses. Some medical cannabis programs also have a patient registry, which can provide protection to medical patients against arrest for possession.¹ In addition, adult-use programs have higher tax rates when all applicable taxes are combined, whereas medical cannabis programs typically have lower or no tax rates. Under Massachusetts law, for instance, medical cannabis is not taxed, compared with the 10.75% marijuana excise tax, 6.25% sales tax, and optional local excise tax of up to 3% for adult-use cannabis.

Beyond the general differences between medical- and adult-use programs across the United States, researchers and public health officials alike must also consider the different provisions (“design”) contained in states’ respective medical-use programs. Product safety testing, for example, varies widely by state, from mandatory testing of all medical cannabis products before purchase and sale to solely testing at the state regulatory agency’s request. There is also varying consistency across states in the regulation of medical dispensary operations, stock limits, and location,⁷ which can affect the functioning and longevity of a program, including how resources are allocated between medical- and adult-use programs. In addition, in some states such as Oregon, different state agencies are responsible for regulating the medical- and adult-use programs, which may further affect the programs beyond policy.

Medical-use programs may have paved the way for adult-use program models in the United States,⁵ but their sustainability may now be at risk in this phase of transition from medical-use only to adult-use. Adult-use programs, which have garnered more focus in recent years, have brought income into states but may not be an effective substitute for medical-use programs, particularly regarding the products and protections needed for patients’ safety and diverse medical needs. Patients, for instance, have a strong preference for topicals and edible forms of cannabis but use combusted forms of cannabis much less frequently than recreational users.^8–10 Previous work has also shown that medical-use program products are higher in CBD on average.¹¹ This is crucial, as research suggests that medical patients, particularly those coping with chronic pain, prefer product formulations that are either high in CBD or those with a balanced 1:1 tetrahydrocannabinol:CBD ratio.¹²

It is also worth noting that many individuals use cannabis for strictly medical reasons, and those reporting strictly medical-use are more likely to be low-income, older, and in poorer health.¹³ Medical dispensaries are one way to ease the cost burden associated with use, as medical-use markets often offer products at a lower price than adult-use¹⁴ or illicit-market¹⁵ sources. Many medical cannabis users report using cannabis as a substitute for other over-the-counter or prescription drugs,¹⁶ leaving individuals at risk of returning to the use of other drugs that may be more harmful but ultimately cheaper than those from the regulated adult-use markets. It is critical for medical-use programs to be structured for sustainability, to ensure that programs do not become artifacts of adult-use cannabis legalization.

To date, little is known about the optimal way for states to transition from medical-use to both medical-use and adult-use markets with distinct functions and goals. Even less is known about how the medical and adult-use markets interact. To our knowledge, no quantitative studies that assess both sales and medical patient data in states that transitioned from medical-use to adult-use legalization have been published in the scientific literature, although one paper tested medical program enrollment numbers from medical-to-adult-use legalization.¹⁷ In this study, Okey et al used medical cardholder data to show that medical patient numbers increase in medical-only years but tend to decrease when both medical- and adult-use cannabis are legal. Another 2 notable papers addressed some of the lessons learned from transitioning markets.^5,18

The current study examines medical- and adult-use cannabis sales and medical patient registration numbers to assess preliminary changes in medical-use programs after adult-use cannabis legalization. Data were assessed from Colorado, Massachusetts, and Oregon, 3 key states that transitioned from solely medical legalization to both medical- and adult-use legalization. Because these states’ policies and programs have important differences in provisions and time frames of enactment and implementation, they offer preliminary insight into how heterogeneity in policies and transition to adult-use legalization may contribute to different outcomes for medical cannabis programs and safety for medical patients over time.

MATERIALS AND METHODS

Study Design

The present quasi-experimental, cross-sectional study was conducted by using cannabis regulatory data from Massachusetts, Colorado, and Oregon. We assessed quarterly medical cannabis sales and patient data from each state’s medical cannabis program, before and after adult-use cannabis retail implementation. Here, we define the date of “adult-use cannabis retail implementation” as the first day that retail operators were permitted to sell cannabis products to adults not already in the states’ medical cannabis registry. We began with a preliminary analysis for exploratory assessment of the association between outcome trends and post–adult-use market time periods. Regression analysis was then used to assess the immediate and gradual changes in medical-use program sales and patient numbers after adult-use dispensaries were implemented in the 3 states.

Measures

Outcomes

The study’s primary outcomes were the quarterly medical cannabis sales and patient registration numbers for states’ medical-use programs after a state either enacted adult-use and permitted constituents to purchase adult-use products through preexisting medical dispensaries or first implemented adult-use dispensaries.

Medical Cannabis Sales

The study examined medical cannabis sales, both by their nominal dollar amounts and as a percentage of the total cannabis sales (ie, medical-use and adult-use sales combined) for the quarter. Adult-use and medical-use sales data were compiled for Massachusetts and Colorado. Massachusetts sales figures for “Adult-use Marijuana Retailer Sales” and “Medical Marijuana Treatment Center Year-To-Date and Gross Sales” were from the Cannabis Control Commission’s Open Data Catalog.¹⁹ Colorado’s adult-use and medical sales data were gathered from the “Marijuana Sales Reports” data set available on the Colorado Department of Revenue’s website.²⁰ Oregon’s retail cannabis sales data for October 2016 to July 2022 were compiled from the “Total Sales” data set maintained by the Oregon Liquor Control Commission.²¹ Oregon first allowed adult-use sales via established medical dispensaries beginning in October 2015; however, sales data are not available until the opening of Oregon’s adult-use market in October 2016, and dispensary sales data were not available (including from early adult-use sales via dispensaries), as the Oregon Medical Marijuana Program under the Oregon Health Authority does not collect sales data.

Patients Registered

Patient data were compiled from all 3 states via their respective medical cannabis governing bodies. Colorado’s patient data were retrieved from the “Number of patients” data set maintained by the Colorado Medical Marijuana Registry under the Colorado Department of Public Health & Environment.²² Massachusetts’s patient data were collected from the “Public Meeting Material” documents publicly available on the Commission’s website.²³ These data are included as part of the “MMJ Licensing and Registration Data,” which provide a monthly snapshot of Massachusetts’s medical market. Patient data for Massachusetts are available from October 2019. Oregon’s medical patient totals were collected from the total patient numbers included in the “OMMP [Oregon Medical Marijuana Program] Quarterly Statistical Snapshot” for each fiscal quarter from January 2015 to July 2022.²⁴

Study Period

The study assessed two cannabis policy measures, medical-use and adult-use dispensary legalization provision implementation. For each of the 3 states, a study period beginning in the first quarter of adult-use legalization implementation and ending in the most recent fiscal quarter was used. Also noted are the dates of coronavirus disease 2019 state of emergency orders, as they may have influenced our results.

Analysis

All analyses were conducted in RStudio using R version 4.1.1 (R Foundation for Statistical Computing, Vienna, Austria). To assess variation in trends for outcomes after the implementation of adult-use cannabis stores for all 3 states, we opted to use a time series analysis in which the first full quarter of adult-use implementation was treated as the first time interval. Table I provides a summary of the time intervals used.

Table I.

Adult-use cannabis implementation time intervals for analysis.

State	Date of Adult-Use Implementation	First Time Interval	Last Time Interval	Total Intervals
Colorado	January 1, 2014	Q1 2014 (January 1, 2014–March 31, 2014)	Q3 2022 (July 1, 2022–September 30, 2022)	35
Massachusetts	November 20, 2018	Q1 2019 (January 1, 2019–March 31, 2019)	Q3 2022 (July 1, 2022–September 30, 2022)	15
Oregon	October 1, 2015	Q4 2015 (October 1, 2015–December 31, 2015)	Q3 2022 (July 1, 2022–September 30, 2022)	28

First Time Interval represents the first full fiscal quarter (Q) since adult-use retail was implemented. Last Time Interval represents the most recent full fiscal quarter.

Correlation Analysis

Pearson correlations were first conducted to estimate the strength and magnitude of the relationship between the dependent variable and time passed since adult-use enactment to gain a high-level understanding of how each of the 3 medical-use markets changed. All correlations and parametric tests were conducted in R.

Regression Analysis

Linear regression was used to assess differences in market indicators in the time since adult-use retail stores were implemented. One model was constructed for each market indicator, in which each indicator (adult-use sales, medical-use sales, medical-use sales as a percentage of total, and number of patients) was regressed on the number of fiscal quarters elapsed since implementation of adult-use retail stores. For all models, we report the characteristics of the regression line using the built-in stats package in R, and relevant parametric test results (eg, F tests, P) were computed by using the psych package.²⁵ Estimations of each models’ 95% CIs were computed by using the confintr package.²⁶

RESULTS

Correlation Analysis

A series of Pearson correlations were conducted to determine the strength and magnitude of the trends in each variable over time (Table II). Our findings indicate that all 3 states showed significant growth in adult-use cannabis sales after marketplaces opened. For the 2 states with medical-use sales information, Colorado did not show an association between medical-use sales and time, but medical-use sales as a percentage of total sales declined significantly after adult-use markets opened; and Massachusetts reported significant increases in medical-use sales after adult-use markets opened, and the percentage of total sales that were medical cannabis did not change significantly. Colorado and Oregon showed significant declines in the number of registered medical patients after the start of adult-use sales; Massachusetts showed a significant increase in the number of registered medical patients after the start of adult-use sales.

Table II.

Correlation between outcome and time since adult-use retail sales were implemented.

Measure	State
	Colorado	Massachusetts	Oregon
Adult-use cannabis sales	0.95***	0.93***	0.87***
Medical-use cannabis sales	−0.27	0.74**	NA
Medical-use cannabis as percentage of total cannabis sales	−0.91***	−0.21	NA
No. of patients	−0.90***	0.89***	−0.94***

Data represent Pearson correlation coefficient (r) between time since adult-use enactment and adult-use cannabis sales, medical-use cannabis sales, medical-use cannabis as percentage of total cannabis sales, and number of registered medical-use cannabis patients. NA = not available.

^*P < 0.05.

^**P < .01.

^***P < .001.

Regression Analysis

Linear regression was used to assess differences in each state’s adult-use sales, medical-use sales, and patient registry numbers in the quarters since implementation of adult-use retail sales (Table III). All results were highly consistent with preliminary analyses.

Table III.

Market trends from the time adult-use retail sales were implemented to the present: results from regression analysis.

Market Variable	State
	Colorado					Massachusetts					Oregon
	β	95% CI	F	P	R2 Adj	β	95% CI	F	P	R2 Adj	β	95% CI	F	P	R2 Adj
Adult-use cannabis sales	12419810	10,972,103 to 13,867,516	305.37	< 0.001***	0.90	24,661,720	19,084,672 to 30,238,768	91.62	<0.001***	0.87	9,487,508	7,152,098 to 11,822,917	70.98	<0.001***	0.75
Medical-se cannabis sales	−421710	−964,242.3 to 120,823.3	2.51	0.123	0.04	3,695,979	1,706,568 to 5,685,390	16.11	0.001**	0.52	NA
Medical-use cannabis as percentage of total cannabis sales	−0.012	−0.014 to −0.01	156.31	<0.001***	0.82	−0.004	−0.017 to −0.008	.62	0.445	0.03	NA
No. of patients	−1112.54	−1306.94 to −918.14	135.57	<0.001***	0.80	3496	2267.73 to 4723.25	40.24	<0.001***	0.78	−2389.6	−2726.22 to −2053.01	212.94	<0.001***	0.89

Market variable was regressed on the number of quarters since adult-use retail sales were implemented. For each model, the beta coefficient (β), 95% CI, F value (F) from the regression model, P value from the regression model, and adjusted R² (R² Adj) were included. NA = not available.

^*P < 0. 05.

^**P < 0.01.

^***P < 0.001.

Adult-Use Sales.

Adult-use sales in all 3 states increased significantly over time. In Colorado, adult-use sales increased by approximately $12.4 million in each quarter elapsed since adult-use implementation (B = 12,419,810; 95% CI, ±1,447,707; P < 0.001). Retail stores in Massachusetts followed a similar pattern, with sales increasing by $24.7 million in each successive quarter (B = 24,661,720; 95% CI, ±5,577,048; P < 0.001). Sales increased by about $9.5 million each quarter in Oregon (B = 9,487,508; 95% CI, ±2,335,409; P < 0.001).

Medical-Use Sales.

Trends in medical-use sales over time since adult-use implementation in Colorado were negative but nonsignificant (B = −421,710; P = 0.123). When models assessed data as a percentage of total cannabis sales, Colorado’s medical market made up ~1% less of the total cannabis market with each quarter: B = −0.01; 95% CI, ±0.002; P < 0.001. In Massachusetts, total medical market sales increased since adult-use implementation by approximately $3.7 million each quarter on average: B = 3,695,979; 95% CI, ±1,989,411; P = 0.001. There were no significant differences in the medical market as a percentage of the total cannabis market over time: B = −0.004; P = 0.445.

Patient Registry Numbers

In Colorado, the average number of patients decreased > 1000 patients per quarter: B = −1112.54; 95% CI, ±194.4; F(1,33) = 135.57; P < 0.001; adjusted R² = 0.80. Similarly, patient numbers in Oregon decreased by ~2400 patients per quarter: B = −2389.6; 95% CI, ±336.6; P <.001; adjusted R² = 0.89. Conversely, patient numbers in Massachusetts increased by an average of ~3500 each quarter: B = 3496; 95% CI, ±1228; P < 0.001.

DISCUSSION

This study using medical-use and adult-use industry metrics across 3 states is the first study, to our knowledge, to quantitively assess the immediate impacts of adult-use retail sales marketplaces on states’ medical program sales and patient registry numbers. Although adult-use models suggest significant increases in adult-use market spending by quarter, models predicting medical-use sales yielded differing results between Colorado and Massachusetts for medical-use sales.

These results highlight key differences in how medical-use programs with varying policies have interacted with the adult-use market, to date. Colorado and Oregon were among the earliest adopters of medical cannabis, but early data suggest that medical-use program sustainability may be adversely affected by the implementation of adult-use markets, notably, retail sales. In Colorado and Oregon, results show a decrease in the number of registered patients after adult-use retail sale implementation. In the first 3 years of implementation of adult-use retail sales, medical patient numbers in Colorado decreased by 22% (January 2014–January 2017) and in Oregon by 55% (October 2015–October 2018). Conversely, Massachusetts medical patient registrations increased by 51% from October 2019 (when patient data were first publicly available) to January 2022. In Colorado, medical-use sales decreased (results were nonsignificant), whereas Massachusetts medical-use sales increased after adult-use retail sale implementation. Although medical cannabis sales were not tracked in Oregon, the number of medical dispensaries declined sharply from 425 in October 2016, as the legal retail market was opening, to 1 dispensary operating in the state in January 2021.²⁴

The sharp decline in patient registrations and medical dispensary numbers in Oregon may have been driven by changes to cannabis provisions in the state. In most states, adult-use dispensaries must be licensed before recreational sales begin. However, Oregon allowed medical storefronts to sell adult-use (nonmedical) products from October 2015 to December 2016, one year before the opening of licensed adult-use retail stores in October 2016.²⁷ The end of this period in January 2017 coincided with a drop in the number of licensed medical establishments, from a peak of 425 in October 2016 to 307 in January 2017; this was a 28% decrease in just 3 months.²⁴ One possible interpretation is that these medical dispensaries developed an adult-use–focused customer base and withdrew their medical license to enter the adult-use market. Notably, adult-use retail stores can sell medical products, but medical dispensaries are not allowed to sell adult-use products, which could incentivize a change in license. Such a possibility has been speculated,²⁸ with one source reporting that > 80% of the > 300 medical shops in business in May 2017 had applied for a recreational license.²⁹

The differing outcomes from Colorado and Oregon compared with those from Massachusetts collectively suggest that medical-use programs undergo important changes after adult-use legalization, with variation that warrants further assessment. Critical differences in policies and priorities may have contributed to the differential outcomes found in this study: goals and policies associated with a medical cannabis program may be better determinants of its coexistence with the adult-use retail market.

Ostensibly, all 3 states seem to have somewhat similar cannabis programs, which include both medical-use and adult-use programs with retail stores and expanded products (“commercialization”), all enacted and implemented from 2010 to 2019. However, because cannabis legalization is a state-led phenomena, there are critical differences in the dates of enactment-to-implementation, policy provisions included in state laws, regulations and other rules, and the enforcement and fidelity of enforcement of these provisions. This heterogeneity could have different impacts on the stability of existing medical-use programs after adult-use cannabis retail store provisions are implemented and as the market saturates throughout the state over time. It is critical that medical-use programs remain viable to provide continued safe and equitable access to medical products that meet patients’ diverse needs.

We also want to note that our results may have been driven in part by emergency policy changes that took place throughout the coronavirus disease 2019 pandemic. In particular, data from quarter 1 and quarter 2 of 2020 in Massachusetts were likely influenced by the states’ decision to issue cease and desist orders to adult-use retailers from March 23 to May 25,³⁰ while medical establishments remained open.³¹ Still, we also note that these increases in patient registration numbers have persisted well beyond 2020 and even hit an all-time high of 104,960 patients in January 2022.²³

Similar to the Colorado and Oregon results reported here, Okey et al¹⁷ also found that medical cannabis enrollment increased over time in the absence of adult-use cannabis and decreased in years when adult-use cannabis was legal in 23 states. Our study results provide additional nuance to this claim by reporting the differences in outcomes across 3 different legalized states with differing cannabis policies and programs, showing that when assessing outcomes of cannabis policy, “the devil is in the details.”³²

In considering the differential outcomes among the 3 states assessed, it is helpful to consider results alongside differences in the legalization process between Oregon and Colorado and their late-adopting counterpart in Massachusetts. All states have a heterogeneous patchwork of provisions, but the overarching goals of the different eras during which provisions were established are important to consider. Oregon is the only 1 of the 3 states to legalize medical-use during the “ballot era” (1996–2000), a period in which medical cannabis laws aimed to protect patients and caregivers but made no claims about the legality of storefronts or group-growing.³³ Colorado legalized medical-use during the early legislative era (2000–2009) that was defined by clearer definitions around legal supply but continued to inhibit legal production. Massachusetts was among the first states to adopt their medical-use program with a licensed dispensary system and guidelines more based in traditional medical care (eg, a bona fide provider–patient relationship with a broad medical assessment).³⁴ Massachusetts is also the only 1 of these 3 states to track and limit medical dispensary density among medical storefronts across the state.⁷ It is a possible that having these statutes in place at such an early stage may have helped to create a more active, robust medical-use market.

These differences in respective legislative efforts likely cascade into differences apparent in these programs today. When considering diagnosing criteria and patient profiles, for instance, many more patients in Colorado report “chronic pain” as their primary condition (78.7%) compared with Massachusetts (19.4%), where mental conditions such as anxiety (21.7%; Colorado, < 0.1%) and depression (3.8%; Colorado, 0%) are much more prevalent.³⁵

The present study shows that medical cannabis markets are not inherently dismantled by the presence of the adult-use market. Rather, our results suggest that there may be specific aspects (ie, provisions, priorities, functionality) of a medical-use program that assist in its sustainability, a phenomenon that additional research may help isolate for future policy. This is critical information for researchers and regulators alike, as it may assist in determining the optimal provisions to meet states’ medical-use and adult-use needs, with foci on safety and equity in cannabis products and access for patients for states that want to prioritize medical-use programs during the transition to adult-use legalization. Although previous work suggested that less regulated programs are more popular to consumers,³⁴ we show a different pattern in our sample. Despite having more “medicalized”regulations than either Colorado or Oregon, Massachusetts’s medical cannabis program exhibits more signs of preservation with continued increases to the medical patient registry and sales.

We also note that some of the variance in medical-use program stability across these states may be attributed to unrelated factors, such as different economic realities of each state, which may affect patient access. To provide some context around these realities, we compared: (1) the median income in each state; and (2) the price of cannabis. Median incomes were retrieved for each state from 2021 ACS (American Community Survey) through the R package tidycensus.^36,37 Lack of available data and different tax structures between states (and municipalities within those states) meant that comparable data were not available for retail sales, and thus we opted to compare wholesale prices obtained from LeafLink,³⁸ a wholesale platform popular in the cannabis industry. We observed that median incomes did differ somewhat between states: Oregon had the lowest median income at $70,084, Colorado was in the middle at $80,184, and the median income in Massachusetts was the highest at $89,026. Wholesale cannabis prices followed a similar pattern as incomes, with Oregon experiencing the lowest wholesale prices ($900.00 per pound) in 2021, followed by Colorado ($1518.72 per pound) and Massachusetts with the highest prices ($3887.93 per pound). It remains a possibility that these economic differences, combined with the lack of access via health insurance, influenced patients’ decisions regarding the medical market. We recommend that future work further consider this issue to determine to what extent economic factors, including lack of insurance, influence the continued use of medical cannabis markets.

There are potential limitations to our work that must also be disclosed. Data availability was not uniform across our study states, limiting analyses and more definitive conclusions regarding outcomes. Patient data were not available for the first 10 months of adult-use retail implementation in Massachusetts, and medical-use sales were not available at all for Oregon. In addition, we were only able to procure and compare data from 3 of 19 states that currently have both adult-use and medical-use cannabis laws. As many of these programs continue to saturate the markets in their respective states, it will be important to compare the trajectories of these medical programs versus those of Colorado, Massachusetts, and Oregon, to assess reliability of policy and provisions that lead to differential outcomes.

Furthermore, our results suggest that Massachusetts experienced a different trajectory of the medical-use program after adult-use retail sale implementation, but this study was unable to discern the specific policy provisions or other factors that may have led to these results. Future work should consider more in-depth assessments of differences in programs within and between states that permit medical-use program viability, and thus sustainability, as well as other factors (including state economics, different modes of access to medicinal cannabis, and manufacturing differences) that may affect potency and effectiveness of cannabis as a treatment modality.

CONCLUSIONS

The present study shows that states’ preexisting medical programs may undergo critical changes after adult-use cannabis legalization is enacted and implemented. Key policy and program differences, such as regulatory differences in the implementation of adult-use retail sales, may have differential impacts on medical-use programs. It is critical that future research assess the differences within and between states’ medical-use and adult-use programs that permit medical-use program sustainability alongside adult-use legalization and implementation.

Figure.

Adult-use medical sales (bar) and medical patient numbers (line) after implementation of adult-use retail. *First quarter of the coronavirus disease 2019 pandemic (January 2020–April 2020).