Placebo for Osteoarthritis Pain

SOURCE: Dieppe P, Goldingay S, Greville-Harris M. The power and value of placebo and nocebo in painful osteoarthritis. Osteoarthritis Cartilage 2016;24:1850-1857.

Terminology about placebo, according to Dieppe et al, might be more useful if divided into placebo response (“a change seen in response to a sham intervention”) and placebo effect (“the difference between doing nothing ... and giving a sham treatment”). The authors chose to focus on the symptomatic improvements that can occur for patients simply as a result of an encounter with a health professional.

By comparing pain reduction achieved in placebo groups of randomized, controlled osteoarthritis trials with treatment arms that received no treatment (not even placebo), the authors determined that an effect size of about 0.5 is seen with placebo, comparable to that seen with many “active” interventions. Context also may be important. For instance, injection placebos were particularly powerful.

The physiologic underpinnings of placebo response for pain indicate it is not “imaginary.” For instance, the pain reduction of placebo can be blocked by pre-administration of naloxone, suggesting that such responses may be reflective of activation of endogenous endorphins.

The authors concluded that positive placebo response from patients occurs most fruitfully when patients feel safe, calm, and validated by their clinician.