Increasing Placebo Responses in the USA Save

A recent analysis of randomized clincal trials (RCT) for the treatment of neuropathic pain has shown in increase in placebo responses. (Citation source http://buff.ly/1LL8yAi)

Published data from RCTs done between 1990-2013, finds that placebo responses have increased considerably, but drug responses have remained stable, thus leading to diminished treatment advantage for the active drug.

These findings are germane to rheumatology where it appears the same phenomenon has evolved.  In recent years it has become harder to prove clinical efficacy and radiographic benefit, largely because of an unexpectedly high placebo response. 

The data is fairly clear. The only real question is what is causing this trend. Is this due to changing trial design?  Or the influence of direct-to-consumer advertising on patient expectations?  Lastly, such trends underscore the problems inherent in RCT comparisons over time.