Systematic review of the emerging literature on the effectiveness of naloxone access laws in the United States

Abstract

Background and aims: Naloxone access laws (NALs) have been suggested to be an important strategy to reduce opioid-related harm. We describe the evolution of NALs across states and over time and review existing evidence of their overall association with naloxone distribution and opioid overdose as well as the potential effects of specific NAL components.

Methods: Descriptive analysis of temporal variation in US regional adoption of NAL components, accompanied by a systematic search of 13 databases for studies (published between 2005 and 20 December 2019) assessing the effects of NALs on naloxone distribution or opioid-related health outcomes. Eleven studies, all published since 2018, met inclusion criteria. Study time-frames spanned 1999-2017. Opioid-related overdose mortality, emergency department episodes and naloxone distribution were correlated with the presence of a NAL and, where data were available, NAL components.

Results: Existing evidence suggests mixed, but generally beneficial, effects for NALs. Nearly all studies show that NALs, particularly those that permit naloxone distribution without patient-specific prescriptions, are associated with increased naloxone access [incidence rate ratios (IRR) range from 1.40, 95% confidence interval (CI) = 1.15-1.66 to 7.75, 95% CI = 1.22-49.35] and increased opioid-related emergency department visits (IRR range from 1.14, 95% CI = 1.07-1.20 to 1.15, 95% CI = 1.02-1.29). Most studies show NALs are associated with reduced overdose mortality, although findings vary depending on the specific NAL components and time-period analyzed (IRR range from 0.66, 95% CI = 0.42-0.90 to 1.27, 95% CI = 1.27-1.27). Few studies account for the variation in opioid environments (i.e. illicit versus prescription) or other policy dimensions that may be correlated with outcomes.

Conclusions: The existing literature on naloxone access laws in the United States supports beneficial effects for increased naloxone distribution, but provides inconclusive evidence for reduced fatal opioid overdose. Mixed findings may reflect variation in the laws' design and implementation, confounding effects of concurrent policy adoption, or differential effectiveness in light of changing opioid environments.

Keywords: Harm reduction; mortality; naloxone; opioids; overdose; pharmacy.

FIGURE 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.

FIGURE 2

Number of states with naloxone access laws (NAL) components 2001–17, by Census Division. Data are to 1 July 2017 from the Prescription Drug Abuse Policy System. US Census Divisions are as follows: East North Central (Wisconsin, Michigan, Illinois, Indiana and Ohio), West North Central (North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa and Missouri), mid-Atlantic (New York, Pennsylvania and New Jersey), New England (Maine, New Hampshire, Vermont, Massachusetts, Connecticut and Rhode Island), East South Central (Kentucky, Tennessee, Mississippi and Alabama), South Atlantic (West Virginia, Maryland, Delaware, Washington DC, Virginia, North Carolina, South Carolina, Georgia and Florida), West South Central (Texas, Oklahoma, Arkansas and Louisiana), Mountain (Montana, Idaho, Wyoming, Utah, Nevada, Colorado, Arizona and New Mexico) and Pacific (Alaska, Washington, Oregon, California and Hawaii).