No-Trickery Placebo

To harness the power of the placebo effect with an inert pill, doctors must take the morally dubious step of tricking their patients into thinking the pill has an active ingredient. Or must they? The first study of its kind, led by Ted Kaptchuk at Harvard Medical School, suggests not, at least not when dealing with patients with irritable bowel syndrome (PLOS One: tinyurl.com/2et68az).

Kaptchuk and his colleagues randomly allocated 37 patients with IBS to receive two inert pills twice daily and 43 to act as no-treatment controls. The former group were told the pills had no active ingredient and were further informed that: 'placebo pills, something like sugar pills, have been shown in rigorous clinical testing to produce significant mind - body self-healing processes'. Before the group allocation, all patients were talked through the benefits and power of the placebo effect by a physician, including the fact that taking the pills is critical for the effect to work.

The researchers took care to ensure that patient - physician contact time and quality was similar across the two groups. Amazingly, the placebo group, even though they knew they were taking inert pills, reported improved symptoms relative to the control group, both at the 11-day mid-point and at the study conclusion after 21 days. The size of this difference was described by the researchers as clinically meaningful (and comparable to active drug treatments), reaching an effect size of .79, which is conventionally considered large. The placebo group also showed greater increases in quality-of-life measures.

'Our results suggest that the placebo response is not necessarily neutralized when placebos are administered openly,' the researchers said. 'Thus our study points to a potential novel strategy that might allow the ethical use of placebos consistent with evidence-based medicine.'

The strength of the results are undermined by the small sample size, the short study length and the possibility that patients were giving the researchers the answers they wanted (a double-blind paradigm was a logical impossibility). For these reasons, the researchers said their work could be considered as a 'proof-of-principle pilot study'.

--Christian Jarrett