The placebo is an integral part of clinical research, helping investigators arrive at the true effect of an experimental treatment.
The mechanisms underlying the placebo effect are not fully understood, but it is clear that if subjects believe they are taking something that could help them, they can experience improvement in signs and symptoms, even by objective measures.
In a recent article about placebos in the May issue of Drug Discovery Today, Professor Edzard Ernst of the Universities of Exeter and Plymouth in Exeter, U.K., reviews some of the recent research into the placebo effect.
He notes that some human ailments seem to respond better to placebo than others. Pain and depression have been noted to respond especially well, he wrote. The article cited a study published last year showing that orally administered glucosamine and chondroitin (which are promoted as a way to ease osteoarthritis pain) are no better than placebo in this regard.
But the study found that 60% of patients receiving placebo indicated at least a 20% decrease in pain score from baseline to week 24 (N Engl J Med.2006;354:795-808). Professsor Ernst also highlighted the findings of eight large acupuncture trials that compared real acupuncture with sham acupuncture (placebo) and no acupuncture. The studies revealed no significant differences between the acupuncture and placebo groups, but did reveal a large and significant difference between the placebo and no-treatment arm.
In concluding remarks, he ironically observed that “no placebos are needed to generate a placebo response in patients; this can also be achieved by active treatments.”
At the 22nd European Association of Urology Congress in Berlin in March, I heard a researcher discuss findings of a study comparing the placebo arms of 16 drug trials to characterize BPH progression. The study confirmed that BPH is a progressive disease based on worsening prostate volume, maximum urinary flow and symptom score, the rate of surgery, and acute urinary retention. Considering how potent the placebo effect can be, I wonder how accurately the study captures the nature of BPH progression.
Placebos generally are thought of in the context of clinical trials, but perhaps rigorous studies of placebos themselves and factors that in-fluence the placebo effect are in order. As Prof. Ernst points out, the knowledge gained might enable researchers to design better clinical trials.