The influence of clinical equipoise and patient preferences on outcomes of conservative manual interventions for spinal pain: an experimental study

BACKGROUND Expected pain relief from treatment is associated with positive clinical outcomes in patients with musculoskeletal pain. Less studied is the influence on outcomes related to the preference of patients and providers for a specific treatment. OBJECTIVES We sought to determine how provider and patient preferences for a manual therapy intervention influenced outcomes in individuals with acutely induced low back pain (LBP). PARTICIPANTS AND METHODS Pain-free participants were randomly assigned to one of two manual therapies (joint biased [JB] or constant touch [CT]) 48 hours after completing an exercise protocol to induce LBP. Expectations for pain relief and preferences for treatment were collected at baseline, prior to randomization. Pain relief was assessed using a 100 mm visual analog scale. All study procedures were conducted in a private testing laboratory at the University of Florida campus. RESULTS Sixty participants were included in this study. After controlling for preintervention pain intensity, the multivariate model included only preintervention pain (B=0.12, p=0.07) and provider preference (B=3.05, p<0.0001) and explained 35.8% of the variance in postintervention pain. When determining whether a participant met his or her expected pain relief, receiving an intervention from a provider with a strong preference for that intervention increased the odds of meeting a participant's expected pain relief 68.3 times (p=0.013) compared to receiving any intervention from a provider with no preference. Receiving JB intervention from any provider increased the odds of meeting expected relief 29.7 times (p=0.023). The effect of a participant receiving an intervention they preferred was retained in the model but did not meet the criteria for a significant contribution. CONCLUSION Our primary findings were that participant and provider preferences for treatment positively influence pain outcomes in individuals with acutely induced LBP, and joint-biased interventions resulted in a greater chance of meeting participants' expected outcomes. This is contrary to our hypothesis that the interaction of receiving an intervention for which a participant had a preference would result in the best outcome.