PACBACK Trial Tests Prevention Strategy for Chronic Low Back Pain

Key Takeaways

• Supported self-management was associated with lower mean low back pain impact than medical care at 10 to 12 months.
• Spinal manipulation did not differ from medical care, and adding it to supported self-management did not improve outcomes further.
• Responder analyses and most secondary outcomes favored supported self-management, although investigators described the mean difference as small.

Among adults with acute or subacute low back pain and moderate to high risk of chronicity, the PACBACK randomized clinical trial found lower mean pain impact at 10 to 12 months with clinician-supported biopsychosocial self-management than with medical care. The mean difference for supported self-management versus medical care was -1.7, with a 95% CI from -2.7 to -0.6.

This 2 × 2 factorial randomized clinical trial was conducted in research clinics at the University of Minnesota and the University of Pittsburgh, Pennsylvania. Enrollment ran from November 2018 to May 2023, and follow-up concluded in June 2024. The trial randomized 1000 adults with acute or subacute low back pain and moderate to high risk of chronicity, and 928 completed follow-up. Participants received one of four 8-week strategies: spinal manipulation therapy, supported self-management, the combination, or guideline-based medical care. The primary endpoint was the low back pain impact score on the NIH Task Force on Chronic LBP scale, which ranges from 8 to 50, during months 10 to 12.

The omnibus test for the primary outcome was statistically significant (p = .006). Compared with medical care, mean low back pain impact scores were lower with supported self-management by -1.7, with a 95% CI from -2.7 to -0.6. The combined self-management and spinal manipulation group showed a mean difference of -1.3, with a 95% CI from -2.5 to 0, while spinal manipulation therapy alone showed -0.3, with a 95% CI from -1.5 to 1.0. In responder analyses, 64% of the supported self-management group and 55% of the medical care group achieved at least a 50% reduction in pain impact. Adding spinal manipulation to supported self-management did not provide additional benefit.

Supported self-management also outperformed medical care on most secondary outcomes, including chronicity and low back pain burden, health care and medication use, productivity, patient-reported outcomes, biopsychosocial measures, and potential mediating psychosocial measures. The supported self-management group also had 12% fewer participants who reported chronic pain that frequently interfered with regular activities. Mediation analyses showed that changes in psychosocial factors at 6 months explained 76% of supported self-management effects at 1 year.