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. 2019 Mar/Apr;134(2):132-140.
doi: 10.1177/0033354919826562. Epub 2019 Feb 5.

Syndromic Surveillance of Emergency Department Visits for Acute Adverse Effects of Marijuana, Tri-County Health Department, Colorado, 2016-2017

Grace E Marx  1   2 , Yushiuan Chen  1 , Michele Askenazi  1 , Bernadette A Albanese  1
Affiliations

Syndromic Surveillance of Emergency Department Visits for Acute Adverse Effects of Marijuana, Tri-County Health Department, Colorado, 2016-2017

Grace E Marx et al. Public Health Rep. 2019 Mar/Apr.

Abstract

Objectives: In Colorado, legalization of recreational marijuana in 2014 increased public access to marijuana and might also have led to an increase in emergency department (ED) visits. We examined the validity of using syndromic surveillance data to detect marijuana-associated ED visits by comparing the performance of surveillance queries with physician-reviewed medical records.

Methods: We developed queries of combinations of marijuana-specific International Classification of Diseases, Tenth Revision (ICD-10) diagnostic codes or keywords. We applied these queries to ED visit data submitted through the Electronic Surveillance System for the Early Notification of Community-Based Epidemics (ESSENCE) syndromic surveillance system at 3 hospitals during 2016-2017. One physician reviewed the medical records of ED visits identified by ≥1 query and calculated the positive predictive value (PPV) of each query. We defined cases of acute adverse effects of marijuana (AAEM) as determined by the ED provider's clinical impression during the visit.

Results: Of 44 942 total ED visits, ESSENCE queries detected 453 (1%) as potential AAEM cases; a review of 422 (93%) medical records identified 188 (45%) true AAEM cases. Queries using ICD-10 diagnostic codes or keywords in the triage note identified all true AAEM cases; PPV varied by hospital from 36% to 64%. Of the 188 true AAEM cases, 109 (58%) were among men and 178 (95%) reported intentional use of marijuana. Compared with noncases of AAEM, cases were significantly more likely to be among non-Colorado residents than among Colorado residents and were significantly more likely to report edible marijuana use rather than smoked marijuana use ( P < .001).

Conclusions: ICD-10 diagnostic codes and triage note keyword queries in ESSENCE, validated by medical record review, can be used to track ED visits for AAEM.

Keywords: ICD-10; marijuana; surveillance; syndromic.

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Conflict of interest statement

Declaration of Conflicting Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Number of eligible emergency department (ED) visits, number of ED visits identified as suspected cases of acute adverse effects of marijuana (AAEM), and number of true AAEM cases determined by chart review, Denver (Colorado) metropolitan area, 2016-2017. Abbreviation: ESSENCE, Electronic Surveillance System for the Early Notification of Community-Based Epidemics.
Figure 2.
Figure 2.
Number of emergency department (ED) visits possibly due to acute adverse effects of marijuana (AAEM) identified by query 5 in 3 hospital systems, Denver (Colorado) metropolitan area, July 1–December 31, 2017. Query 5 refers to an ED visit identified by having any of 4 International Classification of Diseases, Tenth Revision diagnostic codes—T40.7 (poisoning by cannabis), F12.1 (cannabis abuse), F12.2 (cannabis dependence), and F12.9 (cannabis use, unspecified)—or marijuana-specific keywords in the triage note data field (inclusion terms: marijuana, THC, MJ, edible, cannab, smok and weed, smok and pot, pot and brownie; exclusion terms: denies marijuana, denies MJ, denies THC, denies edible, denies cannab, marijuana and synthetic, marijuana and spice, marijuana and mamba, MJ and synthetic, MJ and spice, MJ and mamba). The code for query 5 is available from the authors on request.
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References

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