Precipitated withdrawal induced by prehospital naloxone administration.

Objectives: Buprenorphine is becoming a key component of prehospital management of opioid use disorder (OUD). It is unclear how many prehospital patients might be eligible for buprenorphine induction, as traditional induction requires that patients first have some degree of opioid withdrawal. The primary aim of this study was to quantify how many patients developed precipitated withdrawal after receiving prehospital naloxone for suspected overdose, as they could be candidates for prehospital buprenorphine. The secondary objective was to identify associated factors contributing to precipitated withdrawal, including dose of naloxone administered, and identify rate of subsequent transport.

Methods: A retrospective cohort study reviewing electronic patient care reports (ePCRs) from March 2019 to April 2023 in a single Emergency Medical Services (EMS) system was performed. Cases were included if naloxone was administered during the prehospital interval and excluded if the patient was in cardiac arrest upon arrival and died on scene. Precipitated opioid withdrawal was defined using reliably available ePCR data points measured by the Clinical Opiate Withdrawal Scale (COWS): administration of an antiemetic or sedative, persistent tachycardia, or new tachycardia after naloxone. Descriptive statistics were calculated to quantify the incidence of precipitated withdrawal. Risk RATIOs were calculated to identify variables associated with outcomes of interest. A subgroup analysis was performed examining patients explicitly diagnosed with an overdose by EMS.

Results: During the study period, 4561 individuals were given naloxone, and 2124 (46.2%) met our proxy criteria for precipitated withdrawal. Patients who received multiple doses of naloxone were more likely to meet our precipitated withdrawal definition versus those who received a single dose (RR 1.2, 95% CI 1.12-1.28). Patients who experienced precipitated withdrawal were more likely to accept transportation than those who did not experience withdrawal (RR 1.08 95% CI 1.04-1.12). Persistent tachycardia (80.3%) was the most common criterion met for our definition of precipitated withdrawal.

Conclusions: Almost half of patients who received a dose of prehospital naloxone for suspected overdose met our proxy criteria for precipitated withdrawal. Patients who met our precipitated withdrawal definition were more likely to have received greater doses of naloxone and were more likely to accept transport to an emergency department.