Aim The aim is to test whether a short psychotherapeutic intervention targeting Post Traumatic Stress Disorder (PTSD) symptoms will have an additional positive effect on the outcomes of the Standard Multidisciplinary Program (SMP) against chronic back pain development.

Focus Patients with back pain often demonstrate symptoms of PTSD measured via the Harvard Trauma Questionnaire Scale (HTQ). It has been found that PTSD and pain may maintain each other.

Methods Thousand consecutive patients with Low Back Pain (LBP) referred to the Spine Center are screened for PTSD. It is expected that 100 patients will meet the inclusion criteria and be randomized to SMP or to SMP plus 10 psychotherapeutic sessions, that will include the shock-trauma method 'Somatic Experiencing'.

Conclusion The project started in 2013, so there have not yet been any results. Currently total reached 65 back pain patients; 34 patients in the SMP + sessions intervention arm.

Effect parameters are: Pain, daily function, EuroQOL and (HTQ), anxiety and depression, fear avoidance (Tampa Scale for Kinesiophobia) on entry, and at 6/12 months.

This "Nested Randomized Trial in a Cohort Design" is one of the very first studies targeting both PTSD and chronic pain-related symptomatology.

Inclusion Criteria:

• Back pain: from 1/2 Y duration or longer
• Trauma according to HTQ

Exclusion Criteria:

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