Do patients' pre-treatment expectations about acupuncture effectiveness predict treatment outcome in patients with chronic low back pain? A secondary analysis of data from a randomised controlled clinical trial.

OBJECTIVE: This secondary analysis of a randomised controlled patient-blinded trial comparing effectiveness and side effect briefings in patients with chronic low back pain (CLBP) investigated the association between patients' pre-treatment expectations about minimal acupuncture treatment and pain intensity as outcome during and after the end of the treatment. METHODS: Chronic low back pain patients with a pain intensity of at least 4 on a numeric rating scale from 0 to 10 received eight sessions of minimal acupuncture treatment over 4 weeks. The primary outcome was change in pain intensity rated on a Numerical Rating Scale (NRS 0-10) from inclusion visit to treatment session 4 and to the end of the treatment. Patients' expectations about the effectiveness of acupuncture were assessed using the Expectation for Treatment Scale (ETS) before randomization. Linear regression was applied to investigate whether patients' pre-treatment expectations predicted changes in pain intensity during and after treatment. RESULTS: A total of 142 CLBP patients (40.1 ± 12.5 years; 65.5% female) were included in our analysis. Patients' pre-treatment expectations about acupuncture treatment were associated with changes in pain intensity after four sessions of minimal acupuncture treatment (b = -0.264, p = 0.002), but not after the end of the treatment. This association was found in females and males. CONCLUSIONS: Our results imply that higher pre-treatment expectations only lead to larger reductions in pain intensity in the initial phase of a treatment, with a similar magnitude for both females and males. As the treatment progresses in the second half of the treatment, adapted expectations or other non-specific effects might play a more important role in predicting treatment outcome.

Effect of Briefing on Acupuncture Treatment Outcome Expectations, Pain, and Adverse Side Effects Among Patients With Chronic Low Back Pain: A Randomized Clinical Trial.

Importance: In observational studies, patients' treatment outcome expectations have been associated with better outcomes (ie, a placebo response), whereas concerns about adverse side effects have been associated with an in increase in the negative effects of treatments (ie, a nocebo response). Some randomized trials have suggested that communication from clinicians could affect the treatment outcomes by changing patients' expectations. Objective: To investigate whether treatment outcome expectations and reported adverse side effects could be affected by different briefing contents before a minimal acupuncture treatment in patients with chronic low back pain (CLBP). Design, Setting, and Participants: This randomized single-blinded clinical trial was conducted among patients with CLBP at 1 outpatient clinic in Switzerland who had a pain intensity of at least 4 on a numeric rating scale from 0 to 10. Different recruitment channels were used to enroll patients. Data were collected from May 2016 to December 2017 and were analyzed from June to November 2018. Interventions: Patients were randomized to receive either a regular expectation briefing or a high expectation briefing (effectiveness) and either a regular adverse side effect briefing or an intense adverse side effect briefing (adverse side effect) in a 2 × 2 factorial design. The intervention (briefing sessions and written materials) was standardized and delivered before the acupuncture treatment, with additional booster informative emails provided during the 4-week, 8-session acupuncture course. Main Outcomes and Measures: The primary end point was the patients' expectations regarding the effectiveness of the acupuncture treatment (Expectation for Treatment Scale [ETS]) after the briefing and the subsequent pain intensity (numeric rating scale). The primary end point for the adverse side effect briefing was the adverse side effect score at the end of the acupuncture treatment, derived from session-by-session assessments of adverse side effects. Results: A total of 152 patients with CLBP (mean [SD] age, 39.54 [12.52] years; 100 [65.8%] women) were included. The estimated group difference (regular vs high) for the ETS was -0.16 (95% CI -0.81 to 0.50, P = .64), indicating no evidence for a difference between intervention groups. There was also no evidence for a difference in pain intensity at the end of the acupuncture treatment between the groups with different expectation briefings. The adverse side effects score in the group with the intense adverse side effect briefing were estimated to be 1.31 times higher (95% CI, 0.94 to 1.82; P = .11) than after a regular adverse side effect briefing, but the finding was not statistically significant. Conclusions and Relevance: In this study, suggestions regarding treatment benefits (placebo) and adverse side effects (nocebo) did not affect treatment expectations or adverse side effects. Information regarding adverse side effects might require more research to understand nocebo responses. Trial Registration: German Clinical Trials Register Identifier: DRKS00010191.