Our aim was to evaluate isolated elements of psychological pain treatments and explore treatment effects on biological stress markers. We employed a single-case experimental design with multiple baselines. Matching pairs of twelve participants (chronic low back pain >6 months; elevated pain-related fear) were randomly assigned to graded in vivo exposure (EXP) or cognitive-behavioral therapy (CBT) in a yoked design. Primary assessments were taken during baseline (7-26 days), treatment (23-44 days) and at 6-months follow-up (11-30 days) including changes in pain symptoms, disability, pain-related fear, acceptance, body confidence, self-efficacy, and positive thoughts. Psycho-educational, behavioral, cognitive, and exposure interventions were compared to baseline. EXP exhibited immediate middle-to-large effects; CBT's small-to-middle effects were delayed. Within the EXP approach, change mainly occurred during exposure but not during psycho-educational sessions. Overall cortisol was lower in EXP than CBT at post-treatment. We recommend integrating exposure elements in the management of CLBP to increase its efficacy. Psycho-educational sessions might not be necessary or should be adapted, e.g. with stronger focus on motivational aspects. Since CBT seemed to produce delayed effects, core CBT interventions such as cognitive restructuring might be added after exposure treatment to sustain therapeutic effects.
Keywords: Alpha-amylase; Biological stress response; Chronic low back pain; Cognitive-behavioral therapy; Cortisol; Exposure therapy; Single-case experimental design; Treatment processes.
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