A “main intoxicant” category in a fatal-poisoning table may partly reflect a classification rule rather than proof that one drug acted alone. In the 2017 Nordic survey, cases without a uniquely identifiable causal drug were assigned using a group hierarchy. The authors explicitly warned that this rule could conceal contributions from other drugs, particularly buprenorphine.
Which deaths were included?
Simonsen and colleagues studied fatal poisonings in a historically defined drug-use population across Denmark, Finland, Iceland, Norway and Sweden during 2017. The country totals were 162, 202, 15, 203 and 408 cases, respectively, totaling 990.
The study’s inclusion definition relied on police or autopsy information about intravenous drug misuse or misuse of substances within specified historical convention schedules. It was not a contemporary clinical diagnostic assessment of every resident. Most cases had medicolegal autopsy and toxicology, with a few medical autopsies included.
Detection and causal assignment were separate steps
Laboratories used screening procedures covering common illicit and medicinal drugs, with additional testing as indicated and routine blood alcohol measurement. Primary findings were confirmed and quantified by specific chromatographic methods. The report did not provide one uniform blood collection site, postmortem interval, storage protocol or analyte-specific detection limit for all five countries.
Cause-of-death assessment incorporated the autopsy report, toxicology, police information and circumstances. A substance’s appearance in the analytical-findings table therefore differed from its assignment as the main intoxicant.
How did the hierarchy operate?
Four groups organized the substances. Group I included heroin/morphine, methadone and several other opioids, as well as cocaine. Group II included various stimulants and other substances. Group III included buprenorphine and benzodiazepines. Group IV covered other drugs and poisons, including ethanol.
Normally, the main intoxicant was the drug judged responsible by the forensic pathologist. If multiple drugs were involved and no single substance could be selected, the drug in the lowest-numbered group was designated the main intoxicant. When multiple drugs belonged to the same group, the substance judged the main contributor was chosen.
Consequently, a Group I drug could receive the primary label in an unresolved mixed-drug death involving a Group III drug. That did not establish that the latter had no causal role. The hierarchy was the study’s historical coding method, not a validated ranking of pharmacological importance for every mixture.
Why buprenorphine exposed the limitation
Buprenorphine is an opioid but appeared in Group III rather than Group I. The authors stated that the hierarchy could camouflage its influence on cause-of-death classification and suggested reorganizing the groups in future work. They separately included buprenorphine when comparing opioid deaths.
The survey found a median of four to six detected drugs per case, excluding ethanol. Such co-detection made a single main category useful for tabulation but potentially incomplete as a description of the toxicological evidence.
What the historical statistics cannot decide
The study did not experimentally measure the toxicity of every detected combination. Nor could one selected category establish an individual’s impairment, dose or isolated mechanism of death. Its 2017 findings also should not be presented as today’s drug-market distribution.
When reading surveillance tables, preserve the distinction between drugs detected, drugs considered contributory and the single category selected for counting. Different coding rules can change that last count without changing the underlying specimens. Related record-based distinctions appear in death certificates versus integrated forensic poisoning assessments.
Primary source
Simonsen KW, Kriikku P, Thelander G, et al. Fatal poisoning in drug addicts in the Nordic countries in 2017. Forensic Science International. 2020;313:110343. doi:10.1016/j.forsciint.2020.110343.
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