Fentanyl-associated fatalities among illicit drug users in Wayne County, Michigan (July 2005-May 2006)

During the summer of 2005, multiple cities in the United States began to report outbreaks of fentanyl-associated fatalities among illicit drug users. The objectives of this study were to (1) determine if an outbreak of fentanyl-associated fatalities occurred in mid-2005 to mid-2006 and (2) to examine trends and compare features of fentanyl-contaminated heroin-associated fatalities (FHFs) with non-fentanyl, heroin-associated fatalities (NFHFs) among illicit drug users.

Baseline prevalence of fentanyl- and heroin-associated deaths was estimated from January to May 2005 based on recorded cause of death (determined by the medical examiner (ME)) using the Wayne County, MI, USA toxicology database. The database was then queried for both FHFs and NFHFs between July 1, 2005 and May 12, 2006. A FHF was defined as having fentanyl or norfentanyl (metabolite) detected in any postmortem biological sample and either (1) detection of heroin or its metabolite (6-acetylmorphine) and/or cocaine or its metabolite (benzoylecgonine) in a postmortem biological specimen or (2) confirmation of fentanyl abuse as the cause of death by the ME or a medical history available sufficient enough to exclude prescription fentanyl or other therapeutic opioid use. A NFHF was defined as detection of heroin, 6-acetylmorphine (heroin metabolite) or morphine in any postmortem biological specimen, heroin overdose listed as the cause of death by the ME, and absence of fentanyl detection on postmortem laboratory testing. Information was systematically collected, trended for each group and then compared between the two groups with regard to demographic, exposure, autopsy, and toxicology data. Logistic regression was performed using SAS v 9.1 examining the effects of age, gender, and marital status with fentanyl group status.

Monthly prevalence of fentanyl-associated fatalities among illicit drug users increased from an average of two in early 2005 to a peak of 24 in May, 2006. In total, 101 FHFs and 90 NFHFs were analyzed. The median age of decedents was 46 and 45 years for the fentanyl and non-fentanyl groups, respectively. Fentanyl-contaminated heroin-associated fatalities (FHFs) were more likely to be female (p = 0.003). Women aged over 44 years (OR = 4.67;95 % CI = 1.29-16.96) and divorced/widowed women (OR = 14.18;95 % CI = 1.59-127.01) were more likely to be FHFs when compared to women aged less than 44 years and single, respectively. A significant interaction occurred between gender and age, and gender and marital status. Most FHFs had central (heart) blood samples available for fentanyl testing (n = 96; 95 %): fentanyl was detected in most (n = 91; 95 %). Of these, close to half had no detectable heroin (or 6-acetylmorphine) concentrations (n = 37; 40.7 %). About half of these samples had detectable cocaine concentrations (n = 20; 54 %). Median fentanyl concentration in central blood samples was 0.02 μg/ml (n = 91, range <0.002-0.051 μg/ml) and 0.02 μg/ml (n = 32, range <0.004-0.069 μg/ml) in peripheral blood samples. The geometric mean of the ratio of central to peripheral values was 2.10 (median C/P = 1.75). At autopsy, pulmonary edema was the most frequently encountered finding for both groups (77 %).

Illicit drugs may contain undeclared ingredients that may increase the likelihood of fatality in users. Gender differences in fentanyl-related mortality may be modified by age and/or marital status. These findings may help inform public health and prevention activities if fatalities associated with fentanyl-contaminated illicit drugs reoccur.