Two-hundred and sixty-one military veterans with chronic low back pain who were prescribed long-term opioid treatment were randomized to receive a nurse care manager-administered medication optimization program (n=131) or psychologist-delivered cognitive behavioural therapy (CBT; n=130). The primary outcome of interest was the Brief Pain Inventory (BPI) score and BPI intensity and interference subscores. Secondary outcomes of interest included disability, pain catastrophizing, substance misuse, quality of life, depression, and anxiety measures. Outcomes were assessed up to 12 months follow-up. Results revealed significantly better improvement in BPI total scores in the medication optimization group vs. the CBT group at 12 months, however, this difference was not clinically important. No differences in secondary outcomes were observed between the two groups.