Correlation between cocaine prices and purity with trends in emergency department visits in a major metropolitan area.

Illicit drug use not only causes acute and chronic adverse health outcomes but also results in a significant burden to health care providers. The objective of this study is to examine the relationship between cocaine prices and purity with emergency department (ED) visits for the Chicago-Naperville-Joliet metropolitan area. Our primary outcome was number of cocaine-related ED visits per quarter provided by the Drug Abuse Warning Network. The predictor variables of cocaine purity and price were provided by the System to Retrieve Information from Drug Evidence database. Autoregressive integrated moving average (ARIMA) regressions were used to estimate the effects of cocaine price and purity on cocaine-related ED visits. Although cocaine prices did not change substantially over time, cocaine purity decreased by over 30 % between 2006 and 2010. ARIMA regression results suggest that cocaine-related ED visits were not significantly associated with powder or crack cocaine prices; however, a decrease in powder cocaine purity was associated with 2,081 fewer ED visits overall from 2007 to 2010. The cocaine trade continues to be a major public health and law enforcement threat to large metropolitan cities like Chicago. Regular monitoring of cocaine purity levels may provide early warning of impending changes in cocaine-related ED visits for law enforcement and health care providers.