Emergency department visits: Opioid overdoses

Syndromic Surveillance Situation Awareness 4/19/2020 - 4/17/2021

  • Surveillance in Oregon (called Oregon ESSENCE - Electronic Surveillance System for the Early Notification of Community-Based Epidemics) provides real-time data to monitor what is happening in emergency departments and participating urgent care clinics in the Tri-County area. The queries include visits among Clackamas, Multnomah, and Washington County residents to an emergency department or urgent care clinic. Note that the facilities can be outside of the Tri-County area. There is a 24-hour reporting delay. For weekly reports, we report on the week prior to the report's release.


  • Using ESSENCE Data will allow us to monitor opioid overdoses that are severe enough to be seen in emergency departments and urgent care settings. We will use these data to monitor trends and to detect geographic and temporal clusters rather than conduct individual case finding.



  • Visit counts for each week are color-coded in the charts below. Blue dots indicate normal visit counts, and yellow or red dots mean the counts for that day are higher than expected. We are looking for sudden and sustained increases in visits.


  • Syndrome queries are based on patient ICD-10 codes, that is the diagnosis at discharge. It is important to note that counts may be unstable and that a warning or alert dose not necessarily indicate an event of public health significance. Depending on the query, some of the visits may be false positives, meaning that the visits were not related to opioid overdoses.



Week 15 ESSENCE overdose visits


Discharge Diagnosis codes include:
Poisoning by and adverse effect of: opium, heroin, other opioids, methadone, synthetic narcotics, or other/unspecified narcotics. ICD-10 codes: T40.0, T40.1, T40.2X (excluding T40.2X6), T40.3, T40.4 (excluding T40.0X6), T40.6 (excluding T40.606 and T40.696)

Between April 19, 2020 - April 17, 2021 the opioid-related visits ranged from 10-33 visits per week, with an average of 24 opioid overdose visits per week. 



Week 15 ESSENCE heroin overdose visits


Discharge Diagnosis codes include:
Poisoning by and adverse effects of: heroin. ICD-10 code: T40.1

Between April 19, 2020 - April 17, 2021, heroin overdose visits ranged from 1-9 visits per week, with an average of 5 heroin visits per week.



Syndromic surveillance uses existing clinical data for the purposes of near real-time surveillance. The primary use of emergency department and urgent care clinic visit information is for clinical care and not for surveillance purposes. This secondary use is subject to limitations that should be conidered when interpreting these data.

Both the opioid and heroin queries have high positive predictive values (85% and 98%, respectively). These data should be considered preliminary, there may be gaps in data entry, and the weekly counts may change as the data are entered into ESSENCE.

These data represent counts and not rates; fluctuations in population demographics may influence visits. When comparing jurisdictions these considerations should be taken into account.