Using medical examiner case narratives to improve opioid overdose surveillance

Current opioid overdose mortality surveillance methods do not capture the complexity of the overdose epidemic. Most rely on death certificates, which may underestimate both opioid analgesic and heroin deaths. Categorizing deaths using other characteristics from the death record including route of drug administration may provide useful information to design and evaluate overdose prevention interventions.

We reviewed California Electronic Death Reporting System records and San Francisco Office of the Chief Medical Examiner (OCME) toxicology reports and investigative case narratives for all unintentional opioid overdose deaths in San Francisco County from 2006 to 2012. We chose this time period because it encompassed a period of evolution in local opioid use patterns and expansion of overdose prevention efforts. We created a classification system for heroin-related and injection-related opioid overdose deaths and compared demographic, death scene, and toxicology characteristics among these groups.

We identified 816 unintentional opioid overdose deaths. One hundred fifty-two (19%) were standard heroin deaths, as designated by the OCME or by the presence of 6-monoacetylmorphine. An "expanded" classification for heroin deaths incorporating information from toxicology reports and case narratives added 20 additional heroin deaths (13% increase), accounting for 21% of all opioid deaths. Two hundred five deaths (25%) were injection-related, 60% of which were attributed to heroin. A combined classification of expanded heroin and injection-related deaths accounted for 31% of opioid overdose deaths during this period.

Using additional sources of information to classify opioid overdose cases resulted in a modest increase in the count of heroin overdose deaths but identified a substantial number of non-heroin injection-related opioid analgesic deaths. Including the route of administration in the characterization of opioid overdose deaths can identify meaningful subgroups of opioid users to enhance surveillance efforts and inform targeted public health programming including overdose prevention programs.