To the Editor As addiction medicine physicians providing treatment for individuals using fentanyl, we appreciate the recent publication of a randomized clinical trial evaluating short-term treatment retention associated with a weekly extended-release buprenorphine injection initiated in the emergency department (ED). We were surprised by the very low rates of precipitated withdrawal reported in the trial (0.7% of all patients). This result may be partly explained by the high proportion of patients with buprenorphine present in their urine prior to receiving either study intervention.