Fatal Overdose in the Fourth Wave: Statewide Patterns of Fentanyl, Heroin, and Cocaine

Fatal overdoses involving illicit opioids co-involved with a stimulant, such as cocaine, have become the hallmark of the fourth wave of the overdose crisis. Yet, contemporary demographic patterns and trends remain poorly characterized. This study evaluated Connecticut overdose fatalities for illicit opioids with and without cocaine involvement to identify demographic differences and quantify shifts in drug use over time.

We conducted a retrospective analysis of all confirmed overdose fatalities from 2015–2024 using statewide medical examiner data. Overdose fatalities were grouped as fentanyl/heroin co-involved with cocaine (co-involved), heroin/fentanyl without cocaine (opioid only), or cocaine without heroin/fentanyl (cocaine only). Fatalities from other drugs were excluded. Demographic data included age, race and sex. Fatality group differences were assessed using chi-square tests, multivariate regression models identified demographic predictors of fatality group and annual changes in deaths.

There were 10,317 fatalities over the 10-year period (opioid only - 53.6%, cocaine only - 7.6%, co-involved - 38.8%). Age distribution differed significantly by group (p<0.001): opioid-only deaths were higher among younger individuals (73.3% at ages 18–24; 60.6% at ages 25–34), co-involved deaths peaked in middle adulthood (43.0% at ages 35–44; 42.4% at ages 45–54), and cocaine-only deaths increased with age, comprising 16.6% of fatalities among those aged ≥65. Females had a higher proportion of cocaine-only (9.9% vs 6.8%) and co-involved deaths (40.7% vs 38.2%), whereas opioid-only deaths higher among males (54.9% vs 49.4%; p<0.001). In adjusted multinomial regression, each additional calendar year was associated with a 14% increase in the relative risk of a co-involved fatal overdose compared with opioid-only overdose (aRRR 1.14; 95% CI 1.12–1.16).

Fatal overdoses involving opioid–stimulant co-involvement are increasing and now account for a substantial proportion of overdose mortality in Connecticut. Distinct demographic patterns associated with these fatalities highlight the need for targeted harm-reduction and treatment strategies that address risks related to both opioid and stimulant use.