ISDS Annual Conference Proceedings 2019. This is an Open Access article distributed under the terms of the Creative Commons AttributionNoncommercial 4.0 Unported License (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Online Journal of Public Health Informatics * ISSN 1947-2579 * http://ojphi.org * 11(1): e262, 2019 ISDS 2019 Conference Abstracts Syndrome definitions for drug overdose: How far down the rabbit hole do we go? Alana M. Vivolo-Kantor, Brooke Hoots Division of Unintentional Injury Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States Objective To discuss the process for developing and revising suspected drug overdose queries in syndromic surveillance (SyS) systems. Introduction State and local jurisdictions have been exploring the use of SyS data to monitor suspected drug overdose outbreaks in their communities. With the increasing awareness and use of SyS systems, staff from the Centers for Disease Control and Prevention (CDC) worked to develop several queries that jurisdictions could use to better capture suspected drug overdose visits. In 2017, CDC released their first two queries on heroin overdose and opioid overdose, followed in 2018 by stimulant and all drug overd ose queries. Over time, and with the assistance from the SyS community and the CDC-funded Enhanced State Opioid Overdose Surveillance (ESOOS) state health departments, CDC has revised the queries to address suggestions from jurisdictions. However, it’s not clear how often and in what way the syndrome definitions are updated over time. This is particularly true as new drugs emerge and the names of those drugs are integrated into syndrome definitions (e.g., recent “Spice” and “K2” synthetic cannabi noid outbreaks). Description This roundtable will provide a forum for national, state, and local users of SyS and drug overdose syndrome queries to discuss the process of query development, with an eye towards determining when a definition is “good enough.” CDC staff will facilitate t he discussion and present the current portfolio of drug-related overdose queries. Participants will be encouraged to provide feedback on the queries, share what has been/has not been working in their jurisdiction with regard to syndrome query development, and discuss the process for revising queries as the epidemic evolves. The focus of this roundtable will be on suspected drug overdose query development and revision with emergency department SyS data. http://ojphi.org/