Develop Case Definitions
Emergency Department Case Definition
An emergency department case definition for overdose involves identifying encounters related to drug toxicity, often using a combination of keywords in the chief complaint or discharge diagnosis fields, including terms like “overdose” or “poisoning” with an unspecified or specified drug, and may also incorporate the administration and response to naloxone in the patient’s record. Utilize ICD-10-CM codes (CDC’s 2018 Annual Surveillance Report of Drug-Related Risks and Outcomes) when possible.
Most ED visits classified as overdose are not lab-confirmed by toxicology and will differ from syndromic definitions.
ICD-10-CM Injury Codes for drug-related poisonings are available in CDC’s 2018 Annual Surveillance Report of Drug-Related Risks and Outcomes. Hospital discharge ICD-10-CM definitions used will differ from syndromic definitions, which include additional unstandardized text to assist in the identification of an overdose.
EMS Nonfatal Opioid Overdose Case Definition
An EMS nonfatal overdose case definition often incorporates elements like the administration of naloxone and documented improvement, or specific mentions of overdose-related symptoms or keywords in the patient narrative.
Most jurisdictions already use definitions built on standard EMS fields, and CSTE has worked with national partners to develop a Nonfatal Opioid Overdose Standardized Surveillance Case Definition. This definition uses six validated EMS fields (Provider’s Primary Impression; Provider’s Secondary Impression; Primary Symptom; Other Associated Symptoms; Medication Administered; Response to Medication Administered) along with free-text narrative fields to identify a nonfatal opioid overdose.
The following table highlights NEMSIS data elements that may be useful for developing your own case definition. It is not exhaustive in nature and should not replace any standing jurisdictional guidance.
| Data Source | NEMSIS v3 Variable | NEMSIS v3 Variable Definition | NEMSIS v3 Variable Options |
|---|---|---|---|
| Patient Care Report Narrative | eNarrative.01 - Patient Care Report Narrative | The narrative of the patient care report (PCR). | State, E, 0:1 String values 1-10000 characters |
| Medication Administered by EMS | eMedications.03 - Medication Given | The medication given to the patient. | National, State, R, 1:1 String based on RxNorm (RXCUI) codes Pertinent Negatives (PN): 8801001 – Contraindication Noted 8801003 – Denied By Order 8801007 – Medication Allergy 8801009 – Medication Already Taken 8801019 – Refused 8801023 – Unable to Complete |
| Response to Medication | eMedications.01 - Medication Given | The patient’s response to the medication. | National, State, R, 1:1 Code Description: 9916001 – Improved 9916003 – Unchanged 9916005 - Worse |
| Primary Impression (including ICD-10-CM codes) | eSituation.11 - Provider’s Primary Impression | The EMS personnel’s impression of the patient’s primary problem or most significant condition which led to the management given to the patient (treatments, medications, or procedures). | National, State, R, 1:1 ICD-10-CM codes: (R[0-6][0-9](\.[0-9]{1,4})?|(R73\.9)| (R99))|([A-QSTZ][0-9][0-9A-Z])((\.[0-9A-Z]{1,4})?) |
| Secondary Impression | ESituation.12 - Provider’s Secondary Impressions | The EMS personnel’s impression of the patient’s secondary problem or most significant condition which led to the management given to the patient (treatments, medications, or procedures). | National, State, R, 1:M String values based on ICD-10-CM codes, 1-255 characters |
NSSP Syndrome Definitions for Nonfatal Drug Overdose
In collaboration with NSSP, CDC’s Division of Overdose Prevention (DOP) has developed standardized syndrome definitions tomonitor ED visit-level data for suspected nonfatal overdoses as part of the Drug Overdose Surveillance and EpidemiologySyndromic Surveillance (DOSE-SYS) system. These include eight suspected nonfatal drug overdose-related queries (all drugs,all stimulants, cocaine, methamphetamine, all opioids, heroin, fentanyl, and benzodiazepines).
The queries are updated regularly by the CDC DOP team in partnership with state health departments participating inDOSE and the NSSP Community of Practic.
1. CDC All Drug Overdose v3 Parsed
2. CDC All Stimulant Overdose v4 Parsed
3. CDC Cocaine Overdose v2 Parsed
4. CDC Methamphetamine Overdose v1 Parsed
5. CDC All Opioid Overdose v4 Parsed
6. CDC Fentanyl Overdose v2 Parsed
7. CDC Heroin Overdose v5
8. CDC Benzodiazepine Overdose v2 Parsed
Additional information about how to use and build ESSENCE queries is located on the CDC NSSP website and the CSTE Knowledge Repository.
Connecting the Dots at the Rhode Island Department of Health (RIDOH)
RIDOH created an Opioid Overdose Integrated Surveillance System (ISS) that pairs Emergency Medical Services (EMS) runs with Emergency Department (ED) visits to track non-fatal overdoses statewide. By merging records using name, date of birth, and de-duplicating to one person per day, the system catches cases that one dataset alone might miss. EMS data arrive within an hour of an overdose and ED data within 48 hours, giving RIDOH a near real-time view of overdose trends. Triangulating data sources helps RIDOH identify hot spots to ensure a more complete picture of opioid overdose, improve early detection of anomalies, and inform tailored response strategies in Rhode Island.
For more information: https://ridoh-drug-overdose-surveillance-iss-rihealth.hub.arcgis.com/
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