The Influence of Treatment Expectations on Clinical Outcomes and Cortisol Levels in Patients With Chronic Neck Pain: An Experimental Study.

BACKGROUND

The role of contextual factors like pre-existing treatment expectations has been established. However, the effect of verbally delivered treatment expectations in patient-therapist communication has not been considered, nor has the role of cortisol changes within the placebo/nocebo response in people with chronic neck pain.

OBJECTIVE

To examine the effect of verbally delivered treatment expectations on clinical outcomes in physical therapy practice and to determine if changes in cortisol levels are associated with changes in neck pain and disability.

METHODS

Eighty-three patients with chronic neck pain were randomly allocated to 3 different verbally delivered expectations (positive, negative, neutral) during physical therapy interventions.

MAIN OUTCOME MEASURES

salivary cortisol, pain and disability, and cervical range of motion.

RESULTS

Pain significantly improved in the positive (P < 0.001) and neutral (P < 0.001) expectations groups. For salivary cortisol levels, a significant increase was observed in response to treatment in the neutral (P = 0.045) and negative (P < 0.001) expectations groups. No significant correlations were found between changes in salivary cortisol levels and the change in pain in the neutral and negative expectations groups.

CONCLUSIONS

Physical therapists treating people with chronic neck pain should be attentive when communicating the expected treatment effects to their patients. Whereas verbally delivered positive or neutral expectations may be beneficial for pain-related measures, giving negative expectations may result in a lack of a treatment response on pain. Cortisol levels increased in response to verbally delivered neutral and negative expectations, in the absence of a nocebo effect. This questions the presumed role of cortisol in the nocebo effect.