Statement of purpose The 21st-century surge in national drug-intoxication deaths has been associated with a growing problem of suicide misclassification. Prevention of suicide and lethal drug intoxications depends upon accurate classification of manner of death. This study evaluated interstate variation in reporting drug-intoxication suicides and their potential misclassification according to type of medicolegal death investigation system.

Methods/approach An observational mortality study of all 111,583 drug-intoxication decedents from the 50 states for the period 2008–2010, whose manner of death was suicide, accident, or undetermined intent. Data derived from CDC’s Web-based Injury Statistics Query and Reporting System (WISQARS). The main outcome measure was the rate ratio of combined accident plus undetermined intent to suicide drug-intoxication deaths (indexing potential suicide misclassification), and percentage of intoxication deaths specifying at least one drug (indexing fastidiousness of the death investigation process).

Results Drug-intoxication suicide rates ranged from a high of 3.68 deaths per 100,000 persons in New Mexico to 0.65 per 100,000 in North Dakota. The rate ratio of combined accident and undetermined intent to suicide drug-intoxication deaths ranged from 16.11 in Louisiana (drug-intoxication suicide rate = 0.79 per 100,000) to 2.49 in South Dakota (drug-intoxication suicide rate = 1.74 per 100,000). Adjusting for drug-specification, states with a decentralised coroner system were 46 times more likely to have a high rate ratio (>7.00) of the combined accident plus undetermined intent to suicide drug-intoxication deaths as states with a centralised medical examiner system (95% CI, 3.14–1750.22).

Conclusions Results suggest that the numerous jurisdictions not meeting rigorous standards for conducting medicolegal death investigations are excessively prone to differentially undercounting drug-intoxication suicides.

Significance and contributions There is a national urgency to have uniform state and local death investigation and reporting systems that meet high standards in ascertaining manner of death and providing appropriate surveillance data for evidence-based interventions.