The impact of treatment confidence on pain and related disability among patients with low-back pain : results from the University of California, Los Angeles, low-back pain study

BACKGROUND CONTEXT: Although many researchers and practitioners believe that patients' positive expectations of their treatment favorably influence clinical outcomes, there is little scientific evidence to support this belief. PURPOSE: To describe the level of patients' initial confidence in the success of their assigned treatment, by treatment group and other factors; and to estimate the effects of treatment confidence on subsequent changes in low-back pain and related disability. STUDY DESIGN AND PATIENT SAMPLE: Randomized clinical trial involving 681 patients treated for low-back pain in a managed-care facility in Southern California. OUTCOME MEASURES: Treatment confidence; and changes in three clinical measures of low-back pain: average pain, most severe pain and back-pain-related disability. METHODS: Patients were randomly assigned to one of four treatment groups: medical care with and without physical therapy, and chiropractic care with and without physical modalities. Information was collected by questionnaires at baseline, 2 weeks, 6 weeks and 6 months. Treatment confidence was measured just after randomization on a scale of 0 to 10. RESULTS: Treatment confidence was lowest, on average, for patients assigned to medical care only and highest for patients assigned to medical care plus physical therapy. Other predictors of high treatment confidence were having acute pain and being older, female and nonwhite. Although treatment confidence was only weakly associated with subsequent changes in low-back pain or disability in the total sample, high treatment confidence was associated with greater improvement among patients assigned to medical care plus physical therapy. CONCLUSIONS: Initial confidence in treatment for low-back pain varies by type of care and other factors. Higher confidence may have some beneficial effect on the course of low-back pain in certain patients, but this effect may depend on the type of interaction between client and provider.