Placebo effects in musculoskeletal radiology procedures
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PERSPECTIVE
Placebo effects in musculoskeletal radiology procedures Charles J. Sullivan 1
&
Stephen J. Eustace 1,2 & Eoin C. Kavanagh 1,2
Received: 21 April 2020 / Revised: 29 June 2020 / Accepted: 5 July 2020 # ISS 2020
The word placebo translates from Latin as “I will please” and was originally defined in 1811 as “a medicine given more to please than to benefit the patient” [1]. Placebo use was widespread by the early twentieth century, thought to appease patients without affecting pathophysiology [2]. Studies of angina treatments in the 1930s used the word placebo to describe the inert agent given to control groups [3]. Subsequent research acknowledged therapeutic potential of inert agents in controls, such as Beecher’s quantification of placebo effect magnitude [4]. Revised definitions included the following by Shapiro in the 1960s: “any therapeutic procedure which has an effect on a patient, symptom, syndrome or disease, but which is objectively without specific activity for the condition being treated” [5]. Nocebo effects are adverse effects or worsening of a condition after placebo administration. We hypothesized that placebo analgesia could account for a proportion of the therapeutic effect of analgesic procedures performed by musculoskeletal radiologists and reviewed the relevant literature. The complex mechanisms of placebo effect were described by Goffaux in a triphasic model [6]. The first phase, induction, involves conditions that favor placebo effects, such as therapeutic message and alliance, administration method, the patient’s beliefs and history, and sociocultural factors. Much of patient expectation is formed from the explanation of a procedure in advance by the practitioner, which can influence the placebo effect [7]. Lack of empathy and negative non-verbal behavior such as lack of eye contact contribute to nocebo effects and lessen placebo effects [8]. The second phase of the model involves psychological variables, including conditioning from previous experience, motivation and desire for relief, and emotional state [6]. An optimistic disposition has
been shown to promote focus on recovery and lower pain scores in post-operative patients [9]. The psychological mediators are linked to neurochemical responses: associations have been demonstrated between placebo effects and release of endogenous opioids [10] and endocannabinoids [11]. Following the biological responses, the third phase of actualization involves expression of placebo responses such as subjective changes in pain, emotions, quality of life, and need for additional analgesia and other objective clinical indicators [6]. Placebos are integral to controlled trials, including those involving analgesics. Participants in blinded trials are unsure whether they receive the treatment or placebo; therefore, the placebo effect in such trials is weaker than in clinical practice where the patient may have higher expectation of analgesic effect. A meta-analysis by Vase found a significantly higher placebo mean effect size (0.95) in studies in
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