Generalizability of harm and pain expectations after exposure in chronic low back pain patients.

BACKGROUND Exposure treatments are shown to be effective in reducing pain-related fear and the perceived harmfulness of physical activities. However, due to the fragility of extinction its stability is questionable. We investigated the generalizability of exposure effects in chronic low back pain (CLBP) patients by integrating a behavioral test in the context of an intervention study. METHODS The study is an additional analysis of a randomized controlled trial investigating the efficacy of exposure in vivo. A total of 67 CLBP patients were randomly assigned to one of the three groups: Exposure-short (EXP-S); exposure-long (EXP-L) and cognitive behavioral therapy (CBT). Participants rated the expected harmfulness of daily activities (Photograph Series of Daily Activities) before and after therapy. Post-treatment participants were confronted with an individually tailored, threatening movement in a new context. Harm and pain expectations before the exposure were compared to the actual experience after exposure. RESULTS We found that EXP leads to more strongly reduced harm expectations (F(2,50) = 11.37, p < .001, η2  = 0.31) compared to CBT, regardless of the duration of EXP. After therapy, patients expected less harm (F(2,50) = 3.61, p = .034, η2  = 0.13) but not less pain (F(2,50) = 3.61, p = .034, η2  = 0.13) when confronted with a novel movement. CONCLUSIONS Exposure successfully reduced harm but not pain expectations in patients with CLBP. Further, preliminary results showed that these specific exposure effects were generalized to a novel activity in a different context outside therapy. SIGNIFICANCE This study investigats the generalizability and stability of exposure effects in patients with CLBP by combining a behavioral test with an intervention study. We found strong and stable effects on harm expectations but not on pain expectations. Results show promising preliminary evidence that reduced harm expectations can be generalized to a novel threatening activity in a new context. Clinical implications of our findings suggest that exposure treatment would benefit from a clear focus on harm expectations.