Marijuana and acute health care contacts in Colorado

Highlights

• Hospitalizations with marijuana codes increased from 274 (2010) to 593 (2015) per 100,000.

• Mental illness ED visits with marijuana codes were five-fold higher than without marijuana codes.

• Poison center calls increased after medical and recreational marijuana liberalization.

Abstract

Over 22 million Americans are current users of marijuana; half of US states allow medical marijuana, and several allow recreational marijuana. The objective of this study was to evaluate the impact marijuana has on hospitalizations, emergency department (ED) visits, and regional poison center (RPC) calls in Colorado, a medical and recreational marijuana state. This is a retrospective review using Colorado Hospital Association hospitalizations and ED visits with marijuana-related billing codes, and RPC marijuana exposure calls. Legalization of marijuana in Colorado has been associated with an increase in hospitalizations, ED visits, and RPC calls linked with marijuana exposure. From 2000 to 2015, hospitalization rates with marijuana-related billing codes increased from 274 to 593 per 100,000 hospitalizations in 2015. Overall, the prevalence of mental illness among ED visits with marijuana-related codes was five-fold higher (5.07, 95% CI: 5.0, 5.1) than the prevalence of mental illness without marijuana-related codes. RPC calls remained constant from 2000 through 2009. However, in 2010, after local medical marijuana policy liberalization, the number of marijuana exposure calls significantly increased from 42 to 93; in 2014, after recreational legalization, calls significantly increased by 79.7%, from 123 to 221 (p < 0.0001). The age group < 17 years old also had an increase in calls after 2014. As more states legalize marijuana, it is important to address public education and youth prevention, and understand the impact on mental health disorders. Improvements in data collection and surveillance methods are needed to more accurately evaluate the public health impact of marijuana legalization.

Introduction

In 2011, the Drug Abuse Warning Network (DAWN) estimated marijuana was involved in over 455,668 emergency department (ED) visits in the US, an increase of 62% from 2004. This represented 38.3% of visits involving illicit drugs, second only to cocaine (Substance Abuse and Mental Health Services Administration, 2013). Since 2011, 8 states have legalized retail marijuana, and another 12 have legalized medical marijuana. After the 2016 elections, more than half of US states have now passed legislation to allow medical marijuana and 8 have legalized recreational marijuana (Crary, 2016). Commercialization of marijuana has become a multi-billion dollar industry: in Colorado alone, it is estimated that legalization of marijuana has had a $2.4 billion impact on the state (Light et al., 2016).

The impact marijuana legalization has on various related health outcomes has only begun to be evaluated. Estimates on the prevalence of marijuana use have not appeared to significantly change in the US. According to the 2015 National Survey on Drug Use and Health, an estimated 22.2 million (8.3%) Americans aged 12 years or older are currently users of marijuana (Center for Behavioral Health Statistics and Quality, 2016). In Colorado, past month use increased from 10.1% in 2008/2009 to 16.6% in 2014/2015 (Center for Behavioral Health Statistics and Quality, 2016, Substance Abuse and Mental Health Services Administration, 2). Initial reports of adolescent marijuana use have gone up in Washington, while have not changed in Colorado (Cerda et al., 2017). Unintentional pediatric exposures have gone up in states that have legalized medical marijuana (Wang et al., 2014). Medical marijuana laws are associated with lower state-level opioid related hospital admissions and overdose mortality rates (Bachhuber et al., 2014, Shi, 2017). As more states legalize marijuana, it is imperative to evaluate the public health impact going forward.

Colorado legalized medical marijuana in 2000 with the passing of Amendment 20 (CO Const. Amend. 20 Art. XVIII §14, 2016). Commercialization of medical marijuana increased in 2010, after the U.S. Attorney General's Ogden Memorandum said that they would not prosecute individuals for medical marijuana legal at the state level (Odgen, 2009). Amendment 64 was passed in 2012, allowing dispensary sales of retail/recreational marijuana to begin on January 1, 2014 (CO Const. Amend. 64 Art. XVIII §16, 2012). The objective of this study was to examine the impact marijuana has had on hospitalizations, emergency department (ED) visits, and regional poison center (RPC) calls in Colorado.