Estimating the Need for Naloxone Distribution from United States Emergency Departments

Naloxone is a key intervention for opioid overdose, and emergency departments (EDs) are an important setting for its distribution. Existing estimates rely only on overdose diagnoses, likely missing many patients with an increased risk of opioid overdose (referred to as "at-risk" visits or patients "at risk" throughout this paper), before that point. We sought to create an evidence-based, expanded definition and estimation of at-risk ED visits to better quantify opportunities and volume for naloxone distribution.

We produced an expert-reviewed set of diagnosis codes that identified claims for patients with evidence-based risk factors for opioid overdose, beyond the opioid overdose codes currently in use. Using the 2021 Healthcare Cost and Utilization Project (HCUP) National Emergency Department Sample, we applied linearized survey analysis with stratified weights to quantify the frequency of claims with any matching primary or secondary diagnosis codes and provide a national estimate of qualifying visits. We cross-referenced this estimate with Centers for Disease Control and Prevention (CDC) overdose surveillance data for validation.

We estimate that United States EDs saw at least 3.87 million visits by at-risk patients, compared with 226,000 for treatment of opioid overdose alone. Of these, approximately 3.64 million visits were not classified as overdose cases. Over 900,000 visits involved nonopioid drug use, and more than 40% of visits were covered by Medicaid. At-risk visits represented over 3% of all ED visits nationally.

Our estimate represents a significant increase over previous approaches. We believe this expansion more accurately represents need, can contribute to expanded distribution of naloxone, and will better serve agencies quantifying naloxone in EDs.