The Centers for Disease Control and Prevention (CDC) erroneously reported prescription opioid overdose deaths in 2016 and for more than a decade before.

The error was traced to miscoding of illicitly manufactured fentanyl as prescribed fentanyl, using defined T-codes of the International Classification of Diseases.

Systemic errors begin with error-prone death certificate information provided to the CDC by state registrars of vital statistics.

Besides the fentanyl error, similar limitations were noted for other controlled substances, notably benzodiazepines, cocaine, and methadone.

Most methadone today is used for treating opioid use disorder for which it must be administered or dispensed but not prescribed, according to federal law.

Yet, the CDC characterizes all methadone-related overdose deaths as involving the prescribed version used to treat pain; thus the integrity of the CDC’s prescription drug mortality data remains in question.

The CDC was aware of the error involving fentanyl coding as early as 2005–2007 when illicitly manufactured fentanyl was noted by the CDC in more than a thousand overdose deaths in the U.S.

Yet, the CDC ignored the problem until 2016 data showed serious inconsistencies with other, more reputable, data for prescribing volumes of opioids.

In 2018, the U.S. Congress mandated the CDC to “modernize” its system for reporting drug overdose deaths but this has not yet occurred.