Treatment expectations and preferences as predictors of outcome of acupuncture for chronic back pain

Study Design. Preplanned secondary analysis of data from participants receiving acupuncture in a randomized clinical trial. Objective. To determine whether patients expectations of and preferences for acupuncture predict short and long-term treatment outcomes for persons with chronic back pain. Summary of Background Data. Although accumulating evidence suggests that patient expectations and treatment preferences may predict treatment outcomes, few studies have examined this relationship for acupuncture. Methods. Four hundred seventy-seven acupuncture-naïve participants with chronic low back pain who were randomized to 1 of 3 acupuncture or simulated acupuncture treatments were the focus of this analysis. Ten treatments were provided during a 7-week period, and participants were masked to treatment assignment. Before randomization, participants provided expectations regarding treatment success, impressions, and knowledge about acupuncture and treatment preferences. Outcomes of interest were functional status (Roland score) and symptom bothersomeness at 8 and 52 weeks postrandomization, obtained by telephone interviewers masked to treatment assignment. Results. Persons with high pretreatment expectations for the success of acupuncture were more likely to report greater general expectations for improvement, a preference for acupuncture, having heard acupuncture was a very effective treatment and having a very or moderately positive impression of acupuncture. However, none of these variables was a significant predictor of improvement in back-related symptoms or function at 8 or 52 weeks. After 1 treatment, participants revised expectations of treatment success were only associated with back-symptoms at the end of treatment. After 5 treatments, revised expectation of success was predictive of both symptoms and function at 8 and 52 weeks. Conclusion. Pretreatment expectations and preferences for acupuncture were not found predictive of treatment outcomes for patients with chronic back pain. These results differ from previous studies evaluating acupuncture for chronic back pain. These inconsistent results suggest that the relationship between expectations and outcomes may be more complex than previously believed.