Definitions Matter

In healthcare, the use of appropriate definitions is imperative. I was recently part of an international nominal group technique (a qualitative study that is used to build consensus) that harmonized a definition for contextual factors [1]. Within the literature, contextual factors have been variably described as sociodemographic variables, person-related factors (race, age, patient beliefs and characteristics), physical and social environments, therapeutic alliance, treatment characteristics, healthcare processes, placebo or nocebo, government agencies, and/or cultural beliefs. Our job was to determine which of these characteristics most accurately reflected a contextual factor. Our harmonization (the paper is currently in review), should improve the ability of two clinicians, researchers or laypersons to communicate what they mean by this critical concept.

Manual therapy is the name provided to a heterogeneous group of treatments, many of which involve credible interventions that are grounded in specific therapeutic mechanisms (e.g., ascending and descending pain modulation) [2-4]. There are numerous examples of terminology variations in manual therapy that have created discourse in communication across clinicians, researchers, and policy makers. In 2008, Flynn and colleagues [5] wrote a paper titled “Manual Therapy; we Speak Gibberish”, which outlined the fact that clinicians and researchers use many different terms to define similar constructs. Often, incorrectly.

Incorrect use of terms occurs outside of manual therapy as well. The term, the placebo effect is imprecisely presented in the literature. It is generally introduced with great negativety, with an assumption that it is the same thing as a “placebo”. This erroneous assumption commonly intersects with manual therapy, and is the focus of this blog.

Placebo and Sham

A “placebo” is a substance or an intervention that has no specific therapeutic effect. It is often used as a control in testing new drugs or treatments to better understand the specific effects of the comparator [6]. Examples include a sugar pill, or any other form of treatment that has no specific mechanism [7]. A true placebo study is tailored to mimic an intervention under investigation without producing of any of its characterized mechanistic benefits. Ideally, placebos should also be administered double-blind, alongside other socio-emotional cues (contextual cues) in the patient-practitioner encounter—with the aim of eliciting comparable contextual effects.

In situations in which a placebo cannot be incorporated, a sham treatment is the appropriate substitute [6]. A sham is an inactive procedure that is designed to mimic as closely as possible the active procedure being studied in a clinical trial. The sham procedure should be absent of the active therapeutic effect of the treatment it mimics. Examples include sham saline injections or sham surgery. Shams should still involve blinding (single at least). Both placebo and sham studies provide great insight to our understanding of treatments.

The Placebo Effect

The placebo effect is distinct from a placebo or a sham. A placebo effect is “a generic name for beneficial effects that derive from the context of the clinical encounter, including the ritual of treatment and the clinician-patient relationship, as distinct from therapeutic benefits produced by the specific or characteristic pharmacological or physiological effects of medical interventions” [7]. Another name for the placebo effect could be a catalytic effect or a booster effect. Placebo effects are consistently identified in research studies and may involve reduced activity in selected brain areas associated with pain and negative emotion, and increased activity in the lateral and medial prefrontal cortex, ventral striatum and brainstem [8].

The Placebo Effect-It’s Not a Bad Thing

It is important to note that a placebo effect can elevate a treatment that has no therapeutic mechanism to the point where it demonstrates a therapeutic effect. But perhaps most importantly, “the placebo effect may accompany and enhance the effectiveness of medical interventions with demonstrated specific treatment efficacy” [7]. This suggests the placebo effect can make an effective treatment even more effective. The placebo effect is specifically elevated by patient expectations, the ceremony around the treatment, and selected contextual factors that are important to the patient. A nocebo effect influences effects in the opposite manner to placebo effects and is also an important concept to consider [9].

Why is this Important?

The first reason this is important is because we have the capacity to enhance the placebo effect to boost our credible treatments’ clinical therapeutic effect. Using strategies to build on the patients’ expectations, we can maximize the benefit of our treatments of choice. Second, understanding the placebo effect improves how we frame our interventions to clinical colleagues, policy makers, and patients. It reduces the risk of false characterization (degrading) of selected credible treatments that are more likely influenced by the placebo effect, because they involve a greater amount of patient-clinician interaction.

What does this have to do with Manual Therapy?

Manual therapy approaches are commonly influenced by the placebo and the nocebo effect. Because many clinicians don’t understand the difference between the term’s “placebo” and “the placebo effect”, they denigrate manual therapy, and assume it is a placebo; suggesting is has no specific therapeutic effect (which is incorrect). Hopefully, improved understanding of the terms’ appropriate definitions and careful evaluation of the mechanism’s literature will correct this common assumption.

Key Points

  1. A placebo and the placebo effect are not the same thing.
  2. The placebo effect may enhance the effectiveness of a placebo treatment AND a treatment with known credible treatment effectiveness.

References

  1. Cook C, Balliard A, Bent J, et al. An International Consensus Definition for Contextual Factors. Frontiers in Psychology. In Review.
  2. Ellingsen DM, Napadow V, Protsenko E, Mawla I, Kowalski MH, Swensen D, O’Dwyer-Swensen D, Edwards RR, Kettner N, Loggia ML. Brain Mechanisms of Anticipated Painful Movements and Their Modulation by Manual Therapy in Chronic Low Back Pain. J Pain. 2018 Nov;19(11):1352-1365.
  3. Lascurain-Aguirrebeña I, Newham D, Critchley DJ. Mechanism of Action of Spinal Mobilizations: A Systematic Review. Spine (Phila Pa 1976). 2016 Jan;41(2):159-72.
  4. Schmid A, Brunner F, Wright A, Bachmann LM. Paradigm shift in manual therapy? Evidence for a central nervous system component in the response to passive cervical joint mobilisation. Man Ther. 2008 Oct;13(5):387-96.
  5. Flynn TW, Childs JD, Bell S, Magel JS, Rowe RH, Plock H. Manual physical therapy: we speak gibberish. J Orthop Sports Phys Ther. 2008 Mar;38(3):97-8.
  6. Birch S. A review and analysis of placebo treatments, placebo effects, and placebo controls in trials of medical procedures when sham is not inert. J Altern Complement Med. 2006 Apr;12(3):303-10.
  7. Miller FG, Colloca L, Kaptchuk TJ. The placebo effect: illness and interpersonal healing. Perspect Biol Med. 2009 Autumn;52(4):518-39.
  8. Wager T, Atlas L. The neuroscience of placebo effects: connecting context, learning and health. Nat Rev Neurosci. 2015;16:403–418.
  9. Colloca L, Miller FG. The nocebo effect and its relevance for clinical practice. Psychosom Med. 2011 Sep;73(7):598-603.