OPIOID TOXICITY RECURRENCE AFTER AN INITIAL RESPONSE TO NALOXONE

Objective: To determine the frequency and potential predictors of opio id toxicity recurrence after a response to naloxone in adult Emergency Department patients. Methods: A retrospective case-control study of n aloxone-treated patients with opioid toxicity over an 8-year period. B oth the patient response to naloxone and recurrence of opioid toxicity was determined by an expert Delphi Panel. The frequency of opioid tox icity recurrence was compared by the duration of opioid effect, the ro ute of opioid exposure, and the presence of other CNS depressant drugs . Results: Ninety of 221 (41%) cases with a discharge diagnosis of opi oid toxicity were treated with naloxone; six patients were excluded be cause of a lack of toxicity. There was a response to naloxone in 50% o f the 84 cases, and recurrence of toxicity in 31% (95% CI 17-45%) of n aloxone responders. The most common opioids were codeine, heroin, prop oxyphene, and oxycodone/hydrocodone. Recurrence of toxicity was more c ommon with long-acting opioids (p = 0.04), and was not associated with the route of opioid exposure (p = 0.42), or presence of ethanol and o ther CNS depressants (p greater than or equal to 0.87). Conclusion: Op ioid toxicity recurrence after a response to naloxone occurred in appr oximately 1/3 of adult Emergency Department opioid overdose cases. Rec urrence was more common with long-acting opioids and was not associate d with the route of opioid exposure. Other clinically useful predictor s of toxicity recurrence were not identified.