The idea of lying to patients in order to improve the prognosis of their treatment raises all sorts of moral questions. There is a lot of literature discussing these moral dilemmas; this entry is not part of that discourse. I try to avoid writing about morality except in cases where I want to. However, one can imagine how a potentially powerful positive effector that just happens to be a great excuse to lie gathers more support than a simple treatment that does not encourage untruth. Some of that collection of untruth concerns claims of the effectiveness of placebo treatments.
The idea of a strong placebo effect has survived for decades with only sporadic targeted examination. Placebos are typically used as negative controls in medical tests; there are rarely placebo negative controls. The placebo effect is usually examined relative to a generalized out-of-test population. Over the past decade the placebo effect has been more carefully examined. The results are interesting.
1) Placebos do not cure cancer or set broken legs.
2) They are generally ineffective in situations where a clear binary (either cured or not cured) outcome is clearly defined.
3) They are good pain relievers, causing an almost 7% decrease in perceived pain.
4) They only work against pain in 35%-40% of most populations.
5) They are wildly effective in some people.
6) They are effective anti-depressants.
7) They are much better than no treatment for many psychological illnesses.
These data suggest that claims of disappearing kidney stones and vanishing brain tumors are no more common after lying to a patient than giving them the straight dope. On the other hand the severity of the pain caused by passing the kidney stone can be reduced with lies.
The conditions most demonstratively affected by placebo use are those with a neurologic component. That the brain can change itself is a repeating motif of this blog.
The questions of how the benefits of a placebo effect can be more robustly applied to susceptible conditions is worthy of more intense examination.