Participants
mental illness, Pain, back pain, pain, chronic back pain, leg pain, metastasizing cancer
Participants aged 21 to 70 years with back pain for at least half the days of the last 6 months and 1-week pain intensity averaging 4 or higher on the 10-point Brief Pain Inventory were recruited from the Boulder, Colorado, area via printed and digital advertisements. We targeted primary (nociplastic) chronic back pain (CBP), excluding patients with leg pain worse than back pain, a history of metastasizing cancer, pain-related compensation or litigation, or severe mental illness. Participants provided written informed consent as approved by the University of Colorado institutional review board. Race (including American Indian or Alaskan Native, Asian and Pacific Islander, Black, White, and other or unknown), ethnicity, and gender were self-reported by participants; sex assigned at birth was not collected. Participants were randomized to PRT, placebo, or usual care, with equal probability using an imbalance minimization algorithm. No major changes to study protocol occurred after trial commencement, and sample size was determined by power analyses (eMethods in 