Hospital Observation Upon Reversal (HOUR) with Naloxone: A Prospective Clinical Prediction Rule Validation Study

Abstract

Objective: St. Paul’s Early Discharge Rule was derived to determine which patients could be safely discharged from the emergency department after a 1-hour observation period following naloxone administration for opiate overdose. The rule suggested that patients could be safely discharged if they could mobilize as usual; had a normal oxygen saturation, respiratory rate, temperature, heart rate, and Glasgow Coma Scale score. Validation of the St. Paul’s Early Discharge Rule is necessary to ensure that these criteria are appropriate to apply to patients presenting after an unintentional presumed opioid overdose in the context of emerging synthetic opioids and expanded naloxone access. Methods: In this prospective, observational validation study, an emergency medicine provider assessed subjects one hour after administration of prehospital naloxone. Unlike in the derivation study the threshold for normal oxygen saturation was set at 95% and subjects were not immediately discharged after a normal one-hour evaluation (1HE). Subjects were judged to have a normal 1HE if all 6 criteria of the rule were met. Patients were judged to have an adverse event (AE) if they were admitted to the hospital or had one of the pre-established adverse events. Results: 583 subjects received at least one administration of prehospital naloxone, were transported to the study hospital and had a one hour evaluation performed by a provider. Adverse events occurred in 82 (15.4%) subjects. The rule exhibited a sensitivity of 84.2% (95% CI: 76.2 – 92.1%), specificity of 62.1% (95% CI: 57.6 – 66.5%) and a negative predictive value of 95.6% (95% CI: 93.3 – 97.9%). Only one subject with a normal one hour evaluation subsequently received additional naloxone following a presumed heroin overdose. Conclusion: This rule may be used to risk stratify patients for early discharge following naloxone administration for suspected opioid overdose.