Placebo and nocebo effects in transfusion medicine.

BACKGROUND:Our own observations suggested that placebo and nocebo effects may occur with transfusions. However these effects seem to have been poorly studied. OBJECTIVES:To examine published information on, and draw attention to the possibility of, placebo and nocebo effects with transfusion. METHODS:Focused literature review. RESULTS:There is some information on placebo effects with clotting factors and this effect appears modest at best. There is very little published information on this regarding other fresh blood components. Although unknown biologic effects cannot be ruled out, there are hints that placebo effects might operate - especially with red blood cell transfusions. There is practically no information on nocebo effects with transfusions. CONCLUSIONS:There are ways of surmounting the practical and ethical difficulties involved, and obtaining better information on both types of effects. Individualised, contextualised, informed consenting of transfusion recipients may help to enhance placebo, and reduce nocebo, effects. This may be supportable ethically, and desirable clinically, and financially.