Introduction:
Increasing the availability of buprenorphine is an important component of the public health response to the opioid epidemic. As a low-barrier point of contact, emergency departments (EDs) represent a critical setting for buprenorphine initiation, although practices are varied, with local disparities in buprenorphine initiation.1-3. The evolution in ED-initiated buprenorphine and existence of disparities in its application remain undetermined at a national level. We evaluated national trends in ED buprenorphine initiation and demographic and socioeconomic factors associated with its initiation.

Methods:
This retrospective cross-sectional study used encounter-level ED buprenorphine administration and prescribing data from January 1, 2013, to December 31, 2022, from Epic Cosmos, a nationally representative research system encompassing over 1100 hospitals and 7.2 billion encounters. We queried Cosmos for ED encounters involving administration or prescribing of any buprenorphine formulation. To account for year-to-year variation, descriptive results were standardized to a denominator of ED encounters containing opioid-related ICD-10 billing codes (eAppendix in Supplement 1). The University of Illinois Chicago institutional review board exempted the study, with a waiver of informed consent, because it was non–human participant research. The study followed the STROBE reporting guideline. To examine disparities, we fit a multivariate binary logistic regression model using sex, ethnicity, race, age, urban or rural designation, insurance, and social vulnerability index to an outcome of buprenorphine administration or prescribing over the most recent 3 years. Python, version 3.12.0 was used for analysis. Two-sided P < .05 was significant.

Results:
Of 1 632 674 opioid-related encounters from 2013 to 2022, 217 832 involved initiation of buprenorphine (mean [SD] age, 49.0 [15.3] years; 44.3% female and 55.7% male; 2.0% American Indian or Alaska Native, 0.6% Asian, 18.5% Black, 0.3% Native Hawaiian or Other Pacific Islander, 74.9% White, and 3.6% other; 6.8% Hispanic, 89.0% non-Hispanic, and 4.1% unspecified). Emergency encounters involving buprenorphine increased from 2.75% of opioid-related encounters in 2013 to 27.3% in 2022, with increases in administration and prescribing (Figure). Of 745 289 opioid-related ED encounters across 452 684 unique patients in the most recent 3 years, 16.1% were administered (14.8%) or prescribed (5.7%) buprenorphine.