With rates of prescription drug overdose at an all-time high, researchers at Columbia University's Mailman School of Public Health found that among individuals who visited the emergency department, the risk of subsequently dying from prescription drug overdose increased markedly based on how many times they visited the ER. Relative to patients with one or fewer trips to the ER in the previous year, the risk of dying from prescription drug overdose was five times the rate for those with two visits, 17 times for those with three visits, and 48 times for those with four or more visits.

Despite the importance of the ER as a key clinical entry point for patients at high-risk of prescription drug overdose, the new study is among the first to evaluate the relationship between the ER and overdose. Results are published online in the journal Annals of Epidemiology.

"While 'doctor-shopping'— the practice of visiting multiple health care providers to obtain controlled substances— has been shown to be associated with prescription drug overdose in many studies, our investigation demonstrates that the frequency of emergency department visits in the past year is a strong predictor of subsequent death from prescription drug overdose," said Joanne E. Brady, PhD, adjunct assistant professor of Epidemiology at the Mailman School of Public Health and first author.

Nearly 60 percent of drug overdose deaths involve prescription drugs. According to 2011 data, 1.4 million ER visits implicated use of prescription drugs in a manner other than for which it was prescribed.

The researchers analyzed data for the years 2006-2010 from the New York Statewide Planning and Research Cooperative System, a data reporting system that collects emergency department visit data from non-federal hospitals in New York State, including patient characteristics, discharge diagnoses, and procedures received. These records were matched with mortality data for patients who subsequently died.

By comparing 2,732 patients who subsequently died from prescription drug overdose and 2,732 patients who did not, the researchers found substantially increased risk in patients who were diagnosed with substance use disorders or other psychiatric disorders, and who were male, 35-54 years of age, or white. Additionally, patients who subsequently died of a prescription drug overdose were more likely to be discharged against medical advice at the initial emergency room visit.

"Emergency department visits may serve as an important window of opportunity for identifying patients at heightened risk of prescription drug overdose and for implementing evidence-based intervention programs, such as providing these patients and their families with take-home naloxone and drug treatment referral," said senior author Guohua Li, MD, DrPH, professor of Epidemiology at the Mailman School of Public Health and director, Center for Injury Epidemiology and Prevention at Columbia.

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