Kaptchuk et al. are surely correct in asserting the important contribution of warmth, attention,empathy and confidence to the placebo effect they demonstrate. But the converse must also be true: witholding these items is likely to have negative or deleterious effects on symptoms. Unfortunately this negative element was introduced into group 2 patients who were told: "practitioners introduced themselves and stated they had reviewed the patient’s questionnaire and "knew what to do." They then explained that this was "a scientific study" for which they had been "instructed not to converse with patients." This is likely to have falsely exaggerated the benefits of group 3 patients . Their results are therefore difficult to interpret.
It is worth emphasizing that the commonly held view that a placebo response is determined by psychological genesis is false. The placebo effect is highly complex, but evidence suggests it is effected via organic, possibly neuro- humoral mechanisms. The great error is to regard responders as sham, or fake, or to interpret symptoms that do respond as being psychogenic or non-organic.
Competing interests: None declared
Competing interests: No competing interests