The overall aim of the present study is to compare two different psychological methods, Cognitive Behavioural Therapy (CBT) and Graduated Exposure in vivo (EXP) in the treatment of chronic back pain with regard to effectiveness and improvement of pain related disability.

Exploratory research will also be conducted to identify predictors of which patient groups benefit more from which method. This should optimise treatment options and create effective treatment offers for subgroups of pain patients.

Exposure therapy is an effective and economical treatment modality and was shown in a previous pilot study to be superior to CBT in reducing perceived movement limitation. CBT, on the other hand, appeared to be more effective in establishing coping strategies. With the help of the current study it should be possible to compare the effectiveness of both treatment methods and, in perspective, to identify those patient groups that benefit from exposure therapy and thus create a tailor-made treatment programme for subgroups of pain patients.

A total of 380 patients (age: ≥ 18) with chronic back pain and a sufficient degree of impairment will be included and analysed in the study.

According to a recently published study by the Robert Koch Institute with over 62 000 participants, one in six men (17.1%) and one in four women (24.4%) in Germany reported having suffered from chronic low back pain (CLBP) in the last 12 months. CLBP is a major cause of medical costs, absenteeism and disability. Despite apparent advances in medical care, the prevalence of CLBP continues to rise.

According to current guidelines, most of the commonly offered treatments such as injections or surgery are ineffective; only pharmacotherapy shows small effects but carries a high risk of side effects.

Cognitive behavioural therapy (CBT), multidisciplinary approaches with psychological treatment components such as CBT and exercise, supported by psychological elements, improve pain and condition-related disability in the long term. Disappointingly, however, in most studies the effects of multidisciplinary or psychological treatment approaches are small to moderate, and in the case of multidisciplinary approaches, do not always justify the high costs of inpatient programmes. In outpatient care, specific psychological services in addition to pharmacotherapy and physiotherapy are rare.

EXP treatment for pain is a rarely used psychological treatment that specifically addresses the avoidance of physical activity in people with CLBP. In a previous pilot study with 88 participants, the investigators conducted for the first time a short (10 sessions) and a longer (15 sessions) outpatient EXP therapy programme and compared it with a standard 15-session CBT programme:

• EXP was more effective than CBT in reducing movement-related impairment.
• EXP-short outperformed EXP-long in efficiency after 10 sessions, meaning that individuals improved faster when offered fewer sessions.
• EXP could be safely delivered in the outpatient psychological setting, however CBT was more effective than EXP in improving coping strategies.

A specific behavioural measure, the "BAT-BACK" test, successfully identified participants who benefited from EXP in terms of a reduction in pain-related impairment. Therefore, in the future, EXP therapy could be a tailored treatment option to achieve better treatment outcomes in subgroups of CLBP patients. However, studies with more participants are needed to further clarify whether EXP is successful and for which subgroup of patients. The proposed study would be the first to aim to find out which patient group is more likely to benefit from EXP and which from CBT.

Research question and rationale for the project:

Society is currently faced with the challenge of a widespread disease without being able to offer satisfactory treatment options. A comparison of an already established treatment method (CBT) with a still less known and used treatment method (EXP) should create starting points here. In addition, tailoring chronic pain treatment specifically to subgroups of pain patients could improve care.

In addition, EXP therapy is a promising and cost-effective treatment option that could easily be incorporated into multidisciplinary programmes for inpatients or offered by outpatient psychotherapists as part of the newly established 12-hour brief psychotherapy. In order to validate the preliminary results of the pilot study and to answer open questions, a multicentre study with a larger number of participants is implemented.

The study should also lead to a larger number of therapists trained in EXP therapy in different regions in Germany and to an increase in the visibility of the treatment manuals and could lead to a more frequent use of EXP for the benefit of the CLBP population. By publishing the results, the investigators hope to raise awareness, especially among psychological psychotherapists, that brief, manualised, focused treatments may be sufficient to reduce the burden of chronic pain. The identification of predictors will help all practitioners involved in the treatment of chronic pain to identify those patients who are more likely to benefit from EXP and those who are more likely to benefit from CBT.

Inclusion Criteria:

• Chronic low back pain (duration > 6 months, pain on most days of the week)
• Sufficient level of disability, as defined by QBPDS ≥ 15 (Quebec Back Pain Disability Scale)
• Age 18 and above
• Agreeing to participate, verified by completion of informed consent

Exclusion Criteria:

• Back surgeries during the last six months or planned surgeries
• Red Flags
• inability to read or write in German
• pregnancy
• severe alcohol or drug addiction
• psychotic disorders
• another current psychological treatment
• physical inability to attend sessions
• parallel participation in another intervention study

Depression will be controlled for, medication will be required to stay stable until Follow-up and any changes will be controlled for, on-demand ("rescue") medication will be not allowed.