Case Definition

The CDC ESOOS program draws from multiple fields within ED data to classify visits as overdose-related.

First, we use diagnostic codes medical professionals use for clinical diagnosis and insurance billing purposes, for example, International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes or SNOMED (Systematized Nomenclature of Medicine — Clinical Termsexternal icon) codes. Only ICD-10-CM diagnosis codes for “unintentional” or “undetermined” intent drug poisoning are included in the ESOOS definition.

Second, in situations where diagnosis codes are not present, we use the free text field called “chief complaint,” which represents the purpose of an ED visit, for example, “Patient was found unresponsive. EMS provided Narcan and patient said took heroin.” To be included as an overdose-related ED visit based on chief complaint, records must include two components: 1) Text indicating an overdose or poisoning and 2) Text indicating the involvement of a drug. Common misspellings of key search terms, for example, “herion” instead of “heroin,” are also included. Below are samples of overdose / poisoning and drug terms included by the CDC ESOOS program:

Sample Overdose / Poisoning Terms: overdose, ingestion, intoxication, poisoning, loss of consciousness, shortness of breath, altered mental status, unresponsive, snort, nodding off

Sample Drug Terms:

  • Heroin-specific terms: heroin, dope, speedball
  • Opioid-specific terms: opioid, opium, codeine, oxycodone, fentanyl, morphine, tramadol, dilaudid, methadone, buprenorphine, suboxone, opioid brand names (such as Opana, Percocet, and Vicodin), and all heroin-specific terms
  • All drug terms: Drug, poly drug/substance, stimulants (e.g., cocaine, methamphetamine), benzodiazepines (e.g., Xanax), hallucinogens (e.g., PCP or LSD), marijuana, cannabinoids and synthetic cannabinoids, cathinones, and all opioid-specific terms
CDC Guideline for Prescribing Opioids for Chronic Pain