Impact of cocaine price and purity on trends in emergency department visits in Chicago

Background: Changes in illicit drug price and purity not only have important implications for drug control policy, but also for health service utilization.  Illicit drug abusers are more likely to visit Emergency Departments (EDs). According to the Drug Abuse Warning Network, it was estimated about 1 million non-alcohol illicit drug related ED visits annually in the United States, and cocaine-related ED visits accounted about 50% of them. In this study, we examine the empirical relationship of cocaine price and purity with cocaine-related emergency department visits for Chicago Metropolitan Area.

Methods: Cocaine price per gram and purity are derived from the System to Retrieve Information from Drug Evidence (STRIDE), maintained by Drug Enforcement Administration (DEA). Emergency Department visits are estimated from the Drug Abuse Warning Network (DAWN) database.  We examine all cocaine-related ED visits for the period 2004-2010. Autoregressive integrated moving average (ARIMA) models are used to estimate the impact of cocaine prices and purities on number of ED visits. Results are also stratified by age and race/ethnicity.

Results:  In 2004-10, annual cocaine-related ED visits decreased 26% (from 31,113 in 2004 to 23,020 in 2010) in the Chicago metropolitan area.  The majority of cocaine ED visits involved males (66%), African Americans (60%), and people older than 35 years old (75%). Although both powder and crack cocaine price per gram remained relatively stable (around $60 for crack and $40 for powder) during study period, average purities fell substantially over time—decreasing from 69.1% to 50.5% for crack and from 67.7% to 45.1% for powder cocaine. ARIMA regression results suggest that cocaine-related ED visits were not responsive for powder and crack cocaine prices; however, decreases in powder cocaine purity resulted in 2,081 fewer ED visits since 2007.

Conclusions: The cocaine trade continues to be a major public health and law enforcement threat to the United States and large metropolitan cities like Chicago. Interestingly, although cocaine prices have not changed substantially over time, its purity decreased by over 30% after 2006. Our findings suggest this decrease in cocaine purity was associated with significant declines in ED visits. Further research is necessary to examine reasons for the large decline in cocaine purity. For example, this may be related to the economic recession or increased drug law enforcement in recent years. Whatever the reason for the decline in cocaine purity, however, this trend may have resulted in a significant decline in cocaine-related ED visits in Chicago area.