The way in which a placebo is delivered makes a difference to how patients respond, new research reveals. 

Using knee osteoarthritis as an example the systematic review of 149 randomised controlled trials found intra-articular and topical placebo interventions were associated with greater responses than oral placebo.

According to the authors of the study the findings support the notion that placebo treatments can exert clinically relevant effects.

“The method of treatment delivery might influence treatment outcome,” they wrote.

The possibility of different placebo effects need to be considered when assessing the relative efficacies and rankings of active treatments versus different placebos, say the authors in the paper published in the Annals of Internal Medicine.