Outcomes in Distressed Patients With Chronic Low Back Pain: Subgroup Analysis of a Clinical Trial. 
Study Design Subgroup analysis of a controlled clinical trial.  Background Current evidence suggests that people with chronic low back pain who are distressed may require different interventions than do those who are not distressed.  Recently, the enhanced transtheoretical model intervention (ETMI) reported significant improvements in disability and pain and increased physical activity in patients with chronic low back pain compared to physical therapy as usual.  Objectives To compare outcomes between ETMI and physical therapy interventions for participants with and without self-reported distress.  Methods We tested the interaction between intervention (ETMI versus physical therapy) and distress status (using the Medical Outcomes Study 12-Item Short-Form Health Survey cut point), and performed between-group comparisons on 3 separate outcomes (disability, pain, and physical activity) at 3 and 12 months.  Results In the ETMI group, 57 of 108 participants were considered distressed, versus 62 of 106 participants in the physical therapy group.  The interaction between intervention and distress at 12 months was significant.  Participants improved with both interventions, but the magnitude of change in distressed participants who received ETMI was larger than that in distressed participants who received physical therapy (mean ± SD difference from baseline in disability of 6.1 ± 6.1 in the ETMI group, compared with 3.4 ± 6.7 in the physical therapy group).  Conclusion The enhanced transtheoretical model intervention was significantly more effective than physical therapy in participants with distress.  The trial was registered in ClinicalTrials.gov (NCT01631344).  Level of Evidence Therapy, level 2b.  J Orthop Sports Phys Ther 2018;48(6):491-495.  Epub 27 Mar 2018.  doi:10.2519/jospt.2018.7670.