Fatal Opioid Overdose: Military & Non-Military Polysubstance Toxicology Differences

Background: In 2016, 66.4% of fatal overdoses in the U.S. (Seth et al., 2018) and 62.1% among Veterans involved opioids (Peltzman et al., 2020). However, 79.0% of fatal opioid overdoses have been found to involve additional substances (Golladay et al, 2020). Previous research has identified common polysubstance combinations contributing to fatal opioid overdoses in the general population (Jones et al., 2018; National Institute on Drug Abuse, 2021; Hoots et al., 2020) along with fatal and nonfatal in military samples (Park et al 2015; Zedler et al., 2014; Pouget et al., 2017; Bennett et al., 2017). However, no studies have compared opioid-polysubstance toxicology patterns among fatal overdoses in military and non-military samples nor identified the most common opioid-polysubstance pattern among persons with military involvement. Thus, this study asks: What opioid-polysubstance toxicology pattern is most common among persons with military involvement? Are persons with military involvement more or less likely to have opioids and alcohol, opioids and benzodiazepines, opioids and cocaine, and/or opioids and methamphetamines present in their toxicology results than those without military involvement?

Methods: This study used toxicology data on 1,470 individuals, collected from the Marion County Coroner’s Office in Indiana from 2016-2019. Demographics (including military involvement) were obtained from death certificates. Bivariate analyses assessed differences in opioid-polysubstance patterns in fatal overdoses among those with and without military involvement. Four opioid-polysubstance combinations were of focus, based on common patterns identified in previous literature, including opioid-benzodiazepine, opioid-methamphetamine, opioid-cocaine, and opioid-alcohol. A logistic regression model also assessed if these combinations were able to predict military involvement.

Results: The majority of the sample was male (67.8%) and White (74.1%). The mean age was 40.50 years (SD=12.69) and 7.3% of individuals had military involvement (n=108). Regarding toxicology results, those with military involvement most commonly had opioids and alcohol present (27.8%, n=237) while those without military involvement most often had opioids and benzodiazepine present (27.8%, n=379). Bivariate analysis results indicated that persons with military involvement (18.5%, n=20) were significantly less likely to have opioids and benzodiazepine present in their toxicology results than those without military involvement (27.8%, n=379; χ²(1) = 4.384, p<.05, V=.055), along with opioids and methamphetamine (military involvement: 12.0%, n=13; no military involvement: 20.4%, n=278; χ²(1) = 4.420, p<.05, V=.055). However, those with military involvement (27.8%, n=30) were significantly more likely to have opioids and alcohol present (no military involvement: 17.4%, n=237; χ²(1) = 7.249, p<.01, V=.070).

The logistic regression model was significant (χ2(4, N=1,470) =15.073, p<.01, V=.051, Nagelkerke R²=.025). Opioid-alcohol and opioid-benzodiazepine combinations were significant predictors of military involvement. Those with alcohol and opioids present had significantly greater odds of having military involvement (AOR=1.798, p<.05) while those with benzodiazepine and opioids present had significantly lower odds of having military involvement (AOR=.601, p <.05).

Conclusions: Opioid-polysubstance toxicology patterns clearly differ between those with and without military involvement. Thereby, it is crucial to implement policy and programming that addresses the specific polysubstance patterns present within each population to effectively reduce overdose fatalities.