Placebo effect in the treatment of angina pectoris

The interference of placebo effect in the treatment of angina pectoris has been studied in a group of patients with stable angina pectoris, selected on the basis of normal electrocardiogram at rest and a pathologic ergometric electrocardiographic test. It was found that the patients could be divided, according to the results of the exercise test, into two groups: placebo responders and place-bo-non-responders. The anti-anginal effect of beta-blocking agents has been clearly demonstrated only in the placebo-non-responders group. No statistically significant effect of beta-blocking agents was observed in the placebo-responders group. This result shows that it is necessary, in double blind trials, at first to separate placebo-responders from placebo-non responders. Otherwise the correct evaluation of a drug can be modified by the placebo-responders group.