Our results suggest that some types of placebo treatments can be, on average, associated with greater improvements than others. Although our study cannot prove that this association is causal, the results support the notion that some placebo treatments can trigger clinically relevant responses. Our findings warrant further studies testing different types of placebo as well as active treatments directly against each other. We also suggest that treatment options whose contexts vary strongly should be investigated in placebo-controlled trials and head-to- head comparisons. Otherwise, treatments with small specific effects greater than those of their sham controls are withheld from patients even though they work better than standard treatment. Clinicians who treat patients with migraine should be aware that a relevant part of the overall effect they observe in practice might be the result of nonspecific effects and that the size of such effects might differ between treatment modalities. In other words, the method of treatment delivery might have an important influence on outcome. Although our analyses focused on migraine, the same conclusion could well be true for other conditions.
–Karin Meissner and colleagues, JAMA Internal Medicine