The death certificate has always been the primary source data for tracking and measuring what was known per years as an epidemic of prescription drug abuse. Ambiguous or incomplete cause of death entries in death certificates of drug overdose cases are common. Mortality data in most countries are reported using a taxonomy called the International Classification of Diseases (ICD), managed by the World Health Organization (WHO). In this paper, the authors show how the ICD is ill-suited for classifying drug-involved deaths, many of which involve polysubstance abuse and/or illicitly manufactured fentanyl (IMF). In fact, CDC’s methodology for identifying drug overdose deaths lacks precision and sensitivity for properly characterising polysubstance abuse.

Opioids identified in death certificates are categorised according to six ICD T-codes: opium (T40.0), heroin (T40.1), methadone (T40.3), other synthetic narcotics (T40.4), and other and unspecified narcotics (T40.6). Except for opium, heroin, and methadone, all other opioids except those that are unspecified are aggregated in two T-codes (T40.2 & T40.4), depending upon whether they are natural/semisynthetic or synthetic opioids other than methadone. The result is a system that obscures the actual cause of most drug overdose deaths and, instead, just tallies the number of times each drug is mentioned in an overdose situation.

Thanks to a deep analysis of the literature, the authors show how the CDC was at fault for failing to correct the miscoding of IMF since at least 2008 when the CDC initially reported that IMF had caused more than a thousand overdose deaths in 2006-2007. For a decade or more, as the opioid abuse crisis unfolded, the CDC’s annual tally of prescription opioid overdose deaths was overstated each year because of IMF-involved deaths that should not have been coded or counted as prescription opioid overdose deaths. In just one year, 2016, by the CDC’s own reckoning, this error may have skewed the number of prescription opioid overdose deaths by almost half (47.3%, from 32,445 to 17,087). Finally, the authors discuss some of the public policy consequences of this error, the misguided focus by public health and safety officials on pharmaceutical opioids, their prescribers and users, and the pressing necessity for the CDC to reassess how it measures and reports drug-involved mortality.