MasterclassEnhance placebo, avoid nocebo: How contextual factors affect physiotherapy outcomes
Introduction
Every day physiotherapists (PTs) use different tools, such as manual techniques and exercises, to achieve their main professional goals: the improvement of pain, disability and patient's self-perceived health condition. The management of placebo and avoidance of nocebo responses have recently been suggested as promising additional clinical strategies (Gay and Bishop, 2014), generating a wide debate in manual therapy research (Benz and Flynn, 2013, Ingram et al., 2013, Kamper and Williams, 2013).
Placebo and nocebo represent complex and distinct psychoneurobiological phenomena in which behavioural and neurophysiological modifications occur following application of a treatment. The placebo (Latin “I shall please”) is created by the positive psychosocial context that is capable of influencing the patient's brain (Benedetti, 2013). Instead, the nocebo (Latin “I shall harm”) is the result of the negative ritual and therapeutic act on the patient's mind and body (Benedetti et al., 2007, Colloca and Benedetti, 2007, Colloca and Miller, 2011c).
From a psychobiological perspective (Fig. 1), conscious expectation and the unconscious classical conditioning, reward-learning, observational and social learning, modulation of anxiety, desire, motivation, memory and prior experience, somatic focus, personality traits and genetics work as facilitators of placebo or nocebo (Benedetti et al., 2011, Colloca and Miller, 2011b, Colloca, 2014) and modulate different responses across several diseases, illnesses, and treatment methods (Benedetti, 2008, Enck et al., 2013, Schedlowski et al., 2015). Although some attempts to identify (Michener et al., 2013) and to measure (Michener et al., 2015) the placebo response induced by sham techniques have been reported, to date the role of placebo response seems to be poorly recognized and applied by PTs in the clinical setting (Bialosky et al., 2011) and nocebo is still scarcely considered as a possible variable negatively influencing rehabilitation outcome. Agreeing that the conscious reinforcement of placebo strategies could represent an additional opportunity for every PT to improve their clinical outcomes, this masterclass aims to:
- a)
Synthesize the neurobiological mechanisms underlying the placebo and nocebo responses;
- b)
Describe the contextual factors as modulators of clinical outcomes in musculoskeletal rehabilitation;
- c)
Provide guidance for the clinical implementation of placebo enhancement and/or nocebo avoidance;
- d)
Identify possible new lines of investigation in manual therapy research.
Section snippets
The neurobiological mechanisms behind placebo and nocebo responses
Pain and motor performance are the most frequently used models to describe the neural network involved during the placebo and nocebo responses (Tracey, 2010, Carlino et al., 2011, Colloca et al., 2013, Colagiuri et al., 2015).
The contextual factors optimize the rehabilitation outcomes
The psychosocial context and the therapeutic ritual around the patient can also influence the patient's brain activity and the therapeutic outcome such as satisfaction and perceived effect (Colloca and Benedetti, 2005, Benedetti, 2013, Carlino et al., 2014a). As reported in Fig. 3, the physiotherapist's and patient's features, the patient–physiotherapist relationship, the characteristics of the treatment and the overall healthcare setting are the most relevant categories of contextual factors
Implications for clinicians: maximise placebo, minimize nocebo
In therapeutic settings, placebo and nocebo effects are commonly detected. Various systematic reviews have observed placebo when continuous subjective measures of disease are adopted, but not when binary subjective or objective measures are applied (Hróbjartsson and Gøtzsche, 2001, Hróbjartsson and Gøtzsche, 2004, Hróbjartsson and Gøtzsche, 2010). This advocates that placebo does not influence the disease but affects the illness as subjective perceptions of the patient experience (Miller and
Implications for research: design placebo and nocebo trials
The creation of an adequate trial design remains a challenge in placebo and nocebo research (Enck et al., 2011, Vase et al., 2015). Researchers should be aware that the management of the contextual factors is linked to their goals. Limiting the therapeutic relationship and the ritual around the treatment favours immersion of the specific effect of the therapy (Haas et al., 2010, Haas et al., 2014, Salsbury et al., 2014). In contrast, the administration of an active therapy increases the
Conclusion
The difference in clinical success between two different PTs, both practicing with reference to the scientific evidence and application of the clinical guidelines lies in the different level of implementation of the “art” component of the profession. This is probably mostly due to behaviours that have relevant effects on the clinical outcome through placebo or nocebo phenomenon. The possibility of adopting knowledgeable, expert and ethical strategies to enhance placebo and avoid nocebo offers a
Acknowledgements
The authors want to thank Luana Colloca, Elisa Carlino and Alberto Gallace for their valuable advice during the advancement of this manuscript.
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