Nonfatal Overdose and Naloxone Possession Among Homeless Adults in California Who Use Illicit Substances

Objective: To determine the prevalence and factors associated with nonfatal overdose and naloxone possession among homeless adults who use illicit substances. Methods: We used representative cross-sectional data from the California Statewide Study of People Experiencing Homelessness (2021–2022; n=3200), restricting our sample to participants reporting illicit substance use. Our outcomes were recent nonfatal overdose and current naloxone possession. We calculated weighted frequency distributions and conducted separate unadjusted and adjusted Poisson regression models to examine the association between 3 exposures (age of first homelessness, shelter status, and length homeless) and the 2 outcomes. Results: The study population was racially diverse, two-thirds were men, with mean age of 46.1. Half used any illicit substances (49.6%, n=1277), of which 17.8% experienced a nonfatal overdose and 39.2% carried naloxone. In adjusted models, increasing age of first homelessness was associated with lower nonfatal overdose prevalence ratio [PR]=0.88 (95% CI: 0.78–0.99) and naloxone possession (PR=0.92, 95% CI: 0.86–0.99). Those unsheltered outdoors (PR=2.46, 95% CI: 1.56–3.89) and in vehicles (PR=1.66, 95% CI: 0.96–2.86) (reference=sheltered) and those homeless for >1–≤3 years (PR=1.34, 95% CI: 0.74–2.42) and ≥3 years (PR=2.59, 95% CI: 1.79–3.75) (reference= ≤1 year) had a higher prevalence of nonfatal overdose. Those unsheltered outdoors (PR=1.14, 95% CI: 0.96–2.08) and in vehicles (PR=1.62, 95% CI: 1.06–2.49) had a higher prevalence of naloxone possession. Conclusions: Nonfatal overdose is high (<1% in general US population), while naloxone possession was low. Efforts to expand overdose prevention and naloxone access to people experiencing homelessness, particularly racially minoritized groups, those in rural areas, and those unsheltered outdoors and with longer homelessness episodes, may reduce preventable overdoses.