expansive demand reduction approach may transcend the typically perceived boundaries of public health and will un- doubtedly require the engage- ment, efforts, and leadership of individual drug users and communities. Apostolos A. Alexandridis, PhD, MPH Maya Doe-Simkins, MPH Gregory Scott, PhD CONTRIBUTORS All of the authors were involved in the outlining, drafting, and editing of the editorial. M. Doe-Simkins and G. Scott developed specific examples of events in Chicago. ACKNOWLEDGMENTS We thank Nabarun Dasgupta for en- lightening discussions on the topic addressed and Ethan Foote for editorial feedback. Note. A. A. Alexandridis is currently a postdoctoral fellow at the US Food and Drug Administration (FDA). This edito- rial solely reflects the views of the authors and does not necessarily represent FDA’s views or policies, nor is it related to work conducted at the FDA. CONFLICTS OF INTEREST The authors declare no conflicts of interest. REFERENCES 1. Nesoff ED, Branas CC, Martins SS. The geographic distribution of fentanyl-involved overdose deaths in Cook County, Illinois. Am J Public Health. 2020;110(1): 98–105. 2. Scott G, Thomas SD, Pollack HA, Ray B. Observed patterns of illicit opiate overdose deaths in Chicago, 1999–2003. J Urban Health. 2007;84(2): 292–306. 3. Bechteler SS, Kane-Willis K. White- washed: The African American Opioid Epi- demic. Chicago, IL: Chicago Urban League; 2017. 4. Denton JS, Donoghue ER, McRey- nolds J, Kalelkar MB. An epidemic of illicit fentanyl deaths in Cook County, Illinois: September 2005 through April 2007. J Forensic Sci. 2008;53(2):452– 454. 5. Bohnert ASB, Nandi A, Tracy M, et al. Policing and risk of overdose mortality in urban neighborhoods. Drug Alcohol Depend. 2011;113(1):62–68. 6. Carroll JJ, Green TC, Noonan RK. Evidence-Based Strategies for Preventing Opioid Overdose: What’s Working in the United States: An Introduction for Public Heath, Law Enforcement, Local Organiza- tions, and Others Striving to Serve Their Community. Atlanta, GA: Centers for Disease Control and Prevention; 2018. 7. Nikolaides JK, Rizvanolli L, Rozum M, Aks SE. Naloxone access among an urban population of opioid users. Am J Emerg Med. 2018;36(11):2126–2127. Nesoff et al. Comment See also Alexandridis et al., p. 505. In this issue of AJPH, we thank Alexandridis et al. (p. 505) for their thoughtful comments on our work. They assert that “fentanyl-involved opioid overdoses were largely the result of individuals acquiring substances in an inconsistent heroin market,” dissenting with our study’s conclusions. However, our study did not examine the concentration of fentanyl-involved overdoses in isolation; rather, we compared the geographic distribution of fentanyl-involved overdoses rel- ative to the distribution of opioid and polydrug overdoses not in- volving fentanyl. 1 We identified specific neighborhoods where the likelihood that a fatal over- dose involving fentanyl was sig- nificantly elevated compared with fatal overdoses that included other drugs commonly combined with fentanyl (e.g., heroin, cocaine). Heroin was involved in 55% of fentanyl-involved overdoses and 60% of non-fentanyl-involved overdoses. If fentanyl were ran- domly distributed throughout the heroin supply, then we would presumably expect to find no difference in the geographic distributions of the two groups (as demonstrated by the difference in K-functions and the maps of kernel intensity ratio estimates). Our results were consistent across study years (2014–2018), sup- porting our hypothesis that fentanyl-adulterated drugs may not be randomly distributed. Although our study results may be similar to those of studies by Scott et al. 2 and Denton et al. 3 cited by the authors, the evolving nature of the opioid overdose epidemic requires researchers to update data sources and analyses. To base current public health practice and intervention strate- gies on research findings from decades-old data is suboptimal. We agree with Alexandridis et al. that including people who use drugs in research to identify effective overdose prevention strategies is useful and important, but we do not agree that every epidemiological study must in- volve such participation to be a meaningful contribution. Identifying a community of people who use drugs who truly represent the myriad ex- periences and patterns of drug use reflected among people who use drugs is inherently difficult because drug use is a stigma- tized and often hidden behavior. Treatment facilities or harm re- duction services such as needle exchange that have traditionally served as points of contact for engaging people who use drugs in research are not without limitations. One should keep in mind that most people who use drugs do not meet Diagnostic and Sta- tistical Manual of Mental Disorders, Fifth Edition (Washington, DC; American Psychiatric Association; 2013), criteria for substance use disorder and may not need treat- ment, 4 and people who use drugs but do not inject drugs will not be represented in needle-exchange populations. Consequently, a potentially large contingent of people who use drugs at risk for fentanyl-involved overdose from fentanyl-adulterated cocaine; counterfeit medications including benzodiazepines; ketamine; meth- amphetamine; and noninjection heroin use 5 may not be present in much of the research intended to represent their voices. If researchers identify a com- munity by geographic boundaries instead of behaviors, encouraging participation and commitment from a representative group of residents engaged in drug use behavior—as opposed to soliciting community members who are conveniently available and who claim to have witnessed drug use behaviors—much information will be gained. This is unfortunately often not the case with so many “participatory” public health research studies that draw their ABOUT THE AUTHORS The authors are with the Department of Epidemiology, Columbia University Mailman School of Public Health, New York, NY. Correspondence should be sent to Elizabeth D. Nesoff, PhD, MPH, Columbia University Mailman School of Public Health, Department of Epidemiology, 722 W 168th St, 5th Floor, New York, NY 10032 (e-mail: en2408@columbia.edu). Reprints can be ordered at http:// www.ajph.org by clicking the “Reprints” link. This comment was accepted January 11, 2020. doi: 10.2105/AJPH.2020.305574 AJPH SURVEILLANCE April 2020, Vol 110, No. 4 AJPH Nesoff et al. Editorial 507