A 45-year-old male with a history of major depressive disorder and chronic low back pain is referred to the psychiatric clinic by his primary care provider due to concerns about his opioid use. He has been prescribed oxycodone 10 mg every 6 hours for three years following a work injury. He reports that his pain has worsened despite stable dosing and requests an increase. He describes using his medication earlier than prescribed on some occasions, has obtained opioids from a friend twice when he ran out early, and missed his last two follow-up appointments with his PCP. He denies any illicit drug use. He continues to work full-time but reports decreased concentration and irritability. Urine drug screen is positive for oxycodone and negative for other substances. Which assessment finding most reliably distinguishes opioid use disorder from physiological tolerance and pseudoaddiction in this presentation?