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# Deep Dive: Overdose mortality data caveats
- URL: https://www.opioiddata.org/deep-dive-overdose-mortality-data-caveats/
- Published: 2024-08-17T23:46:00.000Z
- Updated: 2024-09-18T06:17:44.000Z
- Description: Caveats to consider when looking at overdose death data in the United States.
- Author: Nabarun Dasgupta
- Tags: Overdose, Data

- There is no local or national source that accurately quantifies drugs entering or circulating in terms of absolute volume. Overdose mortality data are a useful metric because it's the outcome that matters most to most people. But it is at best a proxy for the drug supply.
- Specific substances identified in mortality data are limited by what is assayed for and how they are named in death records.
- Death records in many, but not all, states are public information.
- Causal emphasis on what substance was involved in an overdose can vary by coroner or medical examiner, a [longstanding](https://journals.sagepub.com/doi/full/10.23907/2013.010) problem that has made considerable strides.
- Death certificates are limited by what is measured and recorded. They often contain little/no mental health and social antecedents.
- We cannot systematically distinguish intentional vs. accidental polysubstance use from mortality data.
- Most models do not account for if people moved or died of other causes.
- ICD-10 coding using T-codes [lumps](https://doi.org/10.1007/s40122-021-00254-z) illicitly manufactured fentanyl with pharmaceutical fentanyl.
- Most data dashboards include unintentional deaths and suicides.
- Presence of a substance in post-mortem body fluids doesn't automatically mean that that substance was involved in the fatal event.
- Stimulant-related toxicity has a lot of variation in how it is ascribed in a death.
- There is a 4-18 month delay in cause of death investigations, varying by state resources. Not all states have the same resources for these investigations.
- Coroner-based systems (in contrast to medical examiners) may have [less specific](https://doi.org/10.1080/00952990.2022.2072223) causes of death. Some states have coroners, others do not.
- Incomplete death records are an issue, and missingness is [not distributed uniformly](https://doi.org/10.1016/j.annepidem.2019.08.006).
- There are know differences between urban and rural areas, so a state's average is inherently heterogeneous. Same goes for age, sex, and race.
- Spikes in overdose happen, often based on street drug potency (at the current time). Single month comparisons need to be interpreted in this context.
- Declines in opioid overdose may be offset by increases in other types of substances.