Drug Overdose Case Definitions - Surveillance and Investigation

VDH uses case definitions to identify suspected unintentional drug overdose emergency department (ED) visits. These definitions rely on discharge diagnosis codes and chief complaint (reason for visit) to classify a visit as overdose-related.

Discharge Diagnosis: Suspected overdose-related ED visits are identified using standard medical codes for clinical diagnosis and insurance billing purposes (ICD-9-CM, ICD-10-CM and SNOMED CT). In syndromic surveillance data these codes may be preliminary and may not specify the substance(s) involved in the suspected overdose.
Chief Complaint: Chief complaint is a text field describing why the patient came to the ED. The amount of information in the chief complaint can vary. Definitions include key terms and possible misspellings.

Additional notes:

Intent: The case definitions aim to capture suspect overdose ED visits of unintentional or undetermined intent. However, syndromic surveillance data do not include complete intent information. Some intentional overdose visits may be included.
Disposition: Disposition refers to the patient status at the end of the ED visit (e.g., discharged, admitted, deceased). Although ED visit data is sometimes referred to as “non-fatal” data, the case definitions do not include disposition status. It is possible that some overdose ED visits result in death.

All Drug

VDH All Drug Overdose v5

Automatic Inclusion Criteria (Chief Complaint or Discharge Diagnosis):

Terms: Narcan, naloxone
ICD-9 codes: 965.00, 965.01, 965.02, 965.09, E850.0, E850.1, E850.2
ICD-10 codes (unintentional or undetermined poisoning, initial encounter): T36.0-T36.9, T37.0-T37.9, T38.0-T38.9, T39.0-T39.9, T40.0-T40.9, T41.0-T41.9, T42.0-T42.9, T43.0-T43.9, T44.0-T44.9, T45.0-T45.9, T46.0-T46.9, T47.0-T47.9, T48.0-T48.9, T49.0-T49.9, T50.0-T50.9, T50.A, T50.B, T50.Z, T51.0-T51.9, T52.0-T52.9, T53.0-T53.9, T54.0-T54.9, T55.0-T55.9, T56.0-T56.9, T57.0-T57.9, T58.0-T58.9, T59.0-T59.9, F11.12, F11.22, F11.92
SNOMED CT codes: 295174006, 295175007, 295176008, 295165009, 242253008, 297199006, 295213004, 296321004, 9982009, 27956007, 296325008, 241761001, 296317006, 20260003, 296290006, 61803000, 296291005, 45775001, 45421006, 296329002, 296330007, 57005003

Conditional Inclusion Criteria (Chief Complaint or Discharge Diagnosis). Must have an overdose term and a drug-related term or code and no exclusion terms or codes.

- At least one overdose related term: overdose, poison, ingest, intoxication, unresponsive, loss of consciousness, syncope, altered mental status, shortness of breath

AND

- At least one drug-related term or ICD-10 code: opioid, opiate, opium, morphine, hydrocodone, oxycodone, hydromorphone, oxymorphone, codeine, buprenorphine, fentanyl, methadone, naloxone, tramadol, suboxone, or medication and drug brand names (Dilaudid, Narcan, OxyContin, Percocet, Vicodin, lisdexamfetamine, biphetamine, Adderall, dexedrine, vyvanse, concerta, methylin, ritalin), narcotics, heroin, speed ball, dope, cannabis, lysergide, psychodysleptics, barbiturates, amphetamine, cocaine, pills, benzo, cathinone, cocaine, coke, crack, meth, stimulant, crystal meth, bath salt, MDMA, ecstasy, molly, F11.10, F11.20, F11.90, F14.12, F14.22, F14.92, F15.12, F15.22, F15.92, 269688005, 290222000

AND NO Exclusion Criteria (Chief Complaint or Discharge Diagnosis):

- Terms: withdrawal, detox, suicide, intentional, self-harm, denies drug, denies heroin, denies loss of consciousness, crack and coke references unrelated to overdose (i.e. diet coke, crack tooth, back crack)
- ICD-9 codes: E95-97, V62.84, 965.01
- ICD-10 codes: R45.851, T40.1X1A, T40.1X4A, F14.10, F14.11, F14.13, F14.14, F14.15, F14.18, F14.19, F14.20, F14.21, F14.23, F14.24, F14.25, F14.28, F14.29, F14.90, F14.91, F14.93, F14.94, F14.95, F14.98, F14.99, F15.10, F15.11, F15.13, F15.14, F15.15, F15.18, F15.19, F15.20, F15.21, F15.23, F15.24, F15.25, F15.28, F15.29, F15.90, F15.91, F15.93, F15.94, F15.95, F15.98, F15.99

Opioid or Unspecified (Excluding Heroin)

VDH Opioid and Unspecified Overdose (excluding Heroin) v3

This definition includes visits involving illicit or prescription opioids (except heroin) and visits where the substance is not specified. Visits can meet either the automatic inclusion criteria or the conditional inclusion criteria but are excluded if they have heroin terms or codes.

Automatic Inclusion Criteria (Chief Complaint or Discharge Diagnosis):

Terms: Narcan, naloxone
ICD-9 codes: 965.00, 965.02, 965.09, E850.1, E850.2
ICD-10 codes: T40.0X1A, T40.0X4A, T40.2X1A, T40.2X4A, T40.3X1A, T40.3X4A, T40.4X1A, T40.4X4A, T40.411A, T40.414A, T40.421A, T40.424A, T40.491A, T40.494A, T40.601A, T40.604A, T40.691A, T40.694A, F11.120, F11.121, F11.122, F11.129, F11.220, F11.221, F11.222, F11.229, F11.920, F11.921, F11.922, F11.929
SNOMED CT codes: 295165009, 242253008, 297199006, 295213004

Conditional Inclusion Criteria (Chief Complaint or Discharge Diagnosis). Must have the key term “overdose”, or an overdose related term with a drug-related term or code. Visits must not contain exclusion terms or codes.

- “Overdose” OR

- At least one overdose-related term: poison, ingest, intoxication, unresponsive, loss of consciousness, syncope, altered mental status WITH
- At least one drug-related term or ICD-10 code: opioid, opiate, opium, morphine, hydrocodone, oxycodone, hydromorphone, oxymorphone, codeine, buprenorphine, fentanyl, methadone, naloxone, tramadol, suboxone, or medication and drug brand names (Dilaudid, Narcan, OxyContin, Percocet, Vicodin), F11.10, F11.20, F11.90, AND NO

- Exclusion terms: withdrawal, detox, suicide, intentional, self-harm, on purpose, any specified non-opioid medication or drug, dope, speed ball, denies drug, denies loss of consciousness,

AND NO heroin terms or codes:

ICD-9 codes: E95-97, V62.84, 965.01
ICD-10 codes: R45.851, T40.1X1A, T40.1X4A
SNOMED CT code: 295174006

Heroin

Stimulant

VDH Stimulant Overdose v1

Automatic Inclusion Criteria (Chief Complaint or Discharge Diagnosis):

ICD-9 codes: 969.70, 969.71, 969.72, 969.73, 969.79, 970.0, 970.9, E854.2, E854.3
ICD-10 codes (unintentional or undetermined poisoning, initial encounter): T40.5X1A, T40.5X4A, T43.601A, T43.604A, T43.611A, T43.614A, T43.621A, T43.624A, T43.631A, T43.634A, T43.641A, T43.644A, T43.691A, T43.694A
SNOMED CT codes: 296321004, 9982009, 27956007, 296325008, 241761001, 296317006, 20260003, 296290006, 61803000, 296291005, 45775001, 45421006, 296329002, 296330007, 57005003

Conditional Inclusion Criteria (Chief Complaint or Discharge Diagnosis). Must have an overdose term and a drug-related term or code and no exclusion terms or codes.

At least one overdose related term: overdose, poison, ingest, intoxication, unresponsive, loss of consciousness, syncope, altered mental status, shortness of breath, snort, nod/nodding off

AND

At least one drug-related term or ICD-10 code: amphetamine, medication and drug brand names (lisdexamfetamine, biphetamine, Adderall, dexedrine, vyvanse, concerta, methylin, ritalin), cathinone, speed ball, cocaine, coke, crack, meth, stimulant, crystal meth, bath salt, MDMA, ecstasy, molly, F14.12, F14.22, F14.92, F15.12, F15.22, F15.92

AND NO

Exclusion terms or codes (Chief Complaint or Discharge Diagnosis):
- Terms: withdrawal, detoxification, suicide, intentional, self-harm, denies drug, denies loss of consciousness, cardiac stimulant, crack and coke references unrelated to overdose (i.e. diet coke, crack tooth, back crack), alcohol intoxication
- ICD-9 codes: E95-97, V62.84
- ICD-10 codes: R45.851, T47.2X1A, F14.10, F14.11, F14.13, F14.14, F14.15, F14.18, F14.19, F14.20, F14.21, F14.23, F14.24, F14.25, F14.28, F14.29, F14.90, F14.91, F14.93, F14.94, F14.95, F14.98, F14.99, F15.10, F15.11, F15.13, F15.14, F15.15, F15.18, F15.19, F15.20, F15.21, F15.23, F15.24, F15.25, F15.28, F15.29, F15.90, F15.91, F15.93, F15.94, F15.95, F15.98, F15.99

History of Case Definition Changes

The table below provides a summary of changes made to the drug overdose case definitions by VDH since September 2016.

Month	Description
September 2016	The "Monthly Emergency Department Visits for Overdose by Opioid, Unspecified Substance and Heroin among Virginia Residents" report was first published in September 2016.
July 2017	Three new exclusion terms were added to the Unintentional Overdose by Opioid or Unspecified Substance definition to improve specificity and make it mutually exclusive from the Unintentional Overdose by Heroin definition beginning in the July 2017 report. The exclusion revisions include: “heron” (misspelling of heroin), International Classification of Diseases 9^th Revision (ICD-9) code “965.01” and ICD 10^th Revision (ICD-10) code “T40.1” referencing heroin overdose. This change resulted in a small decrease in the number of ED visits for unintentional overdose by opioid or unspecified substance than previously reported.
May 2018	Case definition revisions were required beginning in the May 2018 report because of submission of SNOMED Clinical Terms (CT) codes by EDs for discharge diagnosis. Reporting of SNOMED CT codes to VDH began in March 2018. One new exclusion term was added to the Unintentional Overdose by Opioid or Unspecified Substance definition to make it mutually exclusive from the Unintentional Overdose by Heroin definition: SNOMED CT code “295174006” for heroin overdose.
June 2018	VDH revised the case definitions based on guidance from the Centers for Disease Control and Prevention (CDC) as well as findings from a data quality evaluation conducted by VDH. While the revised case definitions have increased the sensitivity of capturing valid unintentional overdoses among ED visits reported to VDH, the interpretation of the overdose trends and data found in this report are not impacted. Unintentional Overdose by Opioid or Unspecified Substance definition revisions: Inclusion of F11 category ICD-10 codes for opioid use, abuse and dependence, SNOMED CT codes for opioid and opiate overdose, as well as medication and drug brand names referencing opioid analgesics. Exclusion of terms referencing heroin or denial of drug use. The following exclusion terms used in previous versions of the case definition were removed: alcohol, mental health and addiction. Unintentional Overdose by Heroin definition revisions: Inclusion of common street names referencing heroin and SNOMED CT codes for heroin overdose. Exclusion of discharge diagnosis codes and terms referencing suicide ideation and self-harm to match the Opioid and Unspecified Substance case definition. The following exclusion terms used in previous versions of the case definition were removed: alcohol, mental health and addiction.
August 2018	Three exclusion terms were added to the Unintentional Overdose by Opioid or Unspecified Substance definition to improve specificity and make it mutually exclusive from the Unintentional Overdose by Heroin definition beginning in the August 2018 report. The exclusion revisions were: International Classification of Diseases 9^th Revision (ICD-9) code “965.01” and ICD 10^th Revision (ICD-10) code “T40.1X1A” and "T40.1X4A" referencing heroin overdose. This change resulted in a very small decrease in the number of ED visits for Unintentional Overdose by Opioid or Unspecified Substance for historic data in 2015 and 2016.
November 2018	Three exclusion terms were added to the Unintentional Overdose by Opioid or Unspecified Substance definition to improve specificity and make it mutually exclusive from the Unintentional Overdose by Heroin definition. The exclusions were: "dope", "speed ball", and "speedball". This change resulted in a very small decrease (N=3 visits) in the number of ED visits for Unintentional Overdose by Opioid or Unspecified Substance in historic data.
January 2019	A new case definition was added for All Drug overdose. This case definition includes opioids, heroin, stimulants and other narcotics as well as unspecified overdose where no substance is mentioned.
February 2021	Unintentional Overdose by Opioid or Unspecified Substance case definition updates: Addition of new ICD-10 codes released October 2020 for poisoning by fentanyl or fentanyl analogs, tramadol, and other synthetic narcotics. All Drug Overdose case definition updates: Inclusion of T50.A/B/Z ICD-10 codes for poisoning by bacterial vaccines, viral vaccines, or other vaccines and biological substances. Addition of new ICD-10 codes released October 2020 for poisoning by fentanyl or fentanyl analogs, tramadol, and other synthetic narcotics.
February 2022	A new case definition was added for Stimulant overdose. This case definition includes cocaine (including crack), methamphetamine, ecstasy (MDMA), caffeine, or unspecified stimulants. Stimulant overdoses co-occurring with other substances (e.g., opioids and stimulants) are included.
June 2022	All Drug Overdose case definition updates: Addition of SNOMED codes, drug terms, medication and drug brand names referencing stimulant overdose missing from previous versions along with exclusions for crack and coke references unrelated to overdose. ICD-10 and SNOMED codes for poisonings by anterior pituitary hormones, aspirin or propionic acid derivatives were also added.
October 2025	Edits on this date were to the wording and layout of the webpage. No changes were made to the case definitions.

Last Updated: October 20, 2025