Risk factors of opioid-related overdose among opioid users in an acute care setting: a prospective cohort study

Thesis (Master's)--University of Washington, 2017-06Objective: Opioid-related overdoses cause substantial morbidity and mortality in the United States. This prospective cohort analysis investigated the associations between demographics, overdose history, and drug use and future medically attended opioid overdose events (both fatal and non-fatal). Methods: Baseline data from 241 high-risk opioid users were collected from 2013-2015 in Washington State. These data were linked with medical and death records and analyzed using a Cox proportional hazards model using time to first opioid-related overdose as the outcome of interest. A secondary analysis of all-cause mortality was included. Results: Participants were mostly male (71.4%), white (52.7%), heroin users not on opioid agonist therapy (58.5%), and homeless (52.5%). Heroin use without opiate agonist therapy (OAT) was associated with future opioid overdose, compared to those who used pharmaceutical opioids or were enrolled in OAT, adjusting for intervention status, age, sex, race, and housing status (adjusted Hazard Ratio (aHR) 1.95; 95% CI 1.07, 3.53). Separate models of lifetime history of a previous opioid overdose (aHR, 3.55; 95% CI 1.71, 6.08), poly drug use with depressants when controlling for uppers, (aHR, 2.99; 95% CI 1.47, 6.08), and proportion of days of opioid use alone when comparing the lowest tertile to the highest tertile (aHR, 1.96; 95% CI 1.03, 3.71) were associated with future opioid overdose while adjusting for intervention status, age, sex, race, housing status, and opioid use type. Conclusions: For patients seen in an acute care setting, questions pertaining to one’s opioid agonist therapy status, lifetime opioid overdose history, poly drug use with depressants, and proportion of days using opioids alone were most predictive of one’s future overdose risk. Drug use habits and enrollment in opiate agonist therapy should be discussed with opioid patients in an effort to intervene, educate, and reduce opioid overdoses