Boosting the hypoalgesic effects of spinal manipulative therapy using conditioning and positive expectancy: a placebo study

• Grant number: 19/22924-6
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2021
• End date: January 31, 2024
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Thaís Cristina Chaves
• Grantee: Thaís Cristina Chaves
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 23/03419-4 - Boosting the hypoalgesic effects of spinal manipulative therapy using conditioning and positive expectation: a placebo study, BP.TT; 21/14406-5 - Boosting the hypoalgesic effects of spinal manipulative therapy using conditioning and positive expectation: a placebo study, BP.TT; 21/01842-1 - Boosting the hypoalgesic effects of spinal manipulative therapy using conditioning and positive expectation: a placebo study, BP.TT; 21/02052-4 - Boosting the hypoalgesic effects of spinal manipulative therapy using conditioning and positive expectation: a placebo study, BP.TT

Abstract

The term "contextual effect" has been used to reinforce the view that the placebo effect should be understood as an effect related to the therapeutic context, and not restricted to the use of inert treatments. Thus, the placebo effect is inherent to any therapeutic context and also can be used to enhance the effects of treatment with active components. There is evidence of the effectiveness of manipulative therapy in the treatment of chronic low back pain (CLBP), however, for most physical therapy interventions, its effect is small. Thus, strategies to enhance the effects of this therapy, such as through the use of context factors, may contribute to better therapeutic outcomes. The literature describes conditioning or positive induced expectation models to favor the placebo effect. Although some previous studies have shown that expectation alone or associated with conditioning procedures may intensify hypoalgesic effects of therapies, no previous work has verified the isolated or associated hypoalgesic effect of conditioning and induction of expectancy on treatment in patients with CLBP undergoing manipulative therapy. Thus, the objective of this study will be to identify whether a conditioning procedure through surreptitiously downgrade of nociceptive stimulus intensity associated with positive induced expectation about treatment will result in greater hypoalgesic effects when compared to positive verbal suggestions (expectations) induced or expectation alone regarding the effects of Manipulative Therapy intervention in patients with CLBP. Methods: 222 patients with nonspecific CLBP aged 18 to 65 years will participate in this study. The following primary outcomes will be assessed: pain intensity and overall perception of improvement. All patients will undergo 4 sessions of Manipulative Therapy in the lumbar spine, except the no treatment group (G3). In the first session, patients will be subjected to the inclusion and exclusion criteria and the calibration test to determine the thermal pain threshold, using the Q-sense equipment (Medoc), for the conditioning procedure. In the second treatment session, the groups will initially receive the pre-conditioning test (heat pain) and will be allocated to the following subgroups: hidden conditioning + expectations (G1); positive expectations only (G2) and neutral expectation group (G3). Following, participants will receive specific instructions to induce expectation in G1 and G2, and for the other groups, neutral instructions. Afterwards, patients will receive Manipulative Therapy and again undergo heat-conditioning post-testing. However, G1 will receive hidden conditioning (surreptitiously downgrade of nociceptive stimulus intensity) to reinforce the association between manipulative therapy and pain intensity reduction. The main hypothesis of this study is that the group undergoing hidden conditioning associated with positive induced expectation will have a higher hypoalgesic effect than the other groups. (AU)