title: Epidemiology of emergency department visits for opioid overdose: a population-based study.
abstract: OBJECTIVE
  To evaluate the rate of emergency department (ED) visits for opioid overdose and to examine whether frequent ED visits for opioid overdose are associated with more hospitalizations, near-fatal events, and health care spending.
  
  
  METHODS
  Retrospective cohort study of adults with at least 1 ED visit for opioid overdose between January 1, 2010, and December 31, 2011, derived from population-based data of State Emergency Department Databases and State Inpatient Databases for 2 large and diverse states: California and Florida. Main outcome measures were hospitalizations for opioid overdose, near-fatal events (overdose involving mechanical ventilation), and hospital charges during the year after the first ED visit.
  
  
  RESULTS
  The analytic cohort comprised 19,831 unique patients with 21,609 ED visits for opioid overdose. During a 1-year period, 7% (95% CI, 7%-7%; n=1389 patients) of the patients had frequent (2 or more) ED visits, accounting for 15% (95% CI, 14%-15%; n=3167) of all opioid overdose ED visits. Middle age, male sex, public insurance, lower household income, and comorbidities (such as chronic pulmonary disease and neurological diseases) were associated with frequent ED visits (all P<.01). Overall, 53% (95% CI, 52%-54%; n=11,412) of the ED visits for opioid overdose resulted in hospitalizations; patients with frequent ED visits for opioid overdose had a higher likelihood of hospitalization (adjusted odds ratio, 3.98; 95% CI, 3.38-4.69). In addition, 10.0% (95% CI, 10%-10%; n=2161) of the ED visits led to near-fatal events; patients with frequent ED visits had a higher likelihood of a near-fatal event (adjusted odds ratio, 2.27; 95% CI, 1.96-2.66). Total charges in Florida were $208 million (95% CI, $200-$219 million).
  
  
  CONCLUSIONS
  In this population-based cohort, we found that frequent ED visits for opioid overdose were associated with a higher likelihood of future hospitalizations and near-fatal events.
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA. Electronic address: khasegawa1@partners.org.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: David F M
authors.initials: DF
authors.lastname: Brown
authors.affiliation: Harvard Interfaculty Initiative in Health Policy, Cambridge, MA.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsugawa
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000701:Analgesics, Opioid / Q000009:adverse effects* / Q000506:poisoning; D002140:California; D002423:Cause of Death; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual; D062787:Drug Overdose / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005431:Florida; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009293:Opioid-Related Disorders / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D011159:Population Surveillance; D015995:Prevalence; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid