Nocebo and the potential harm of 'high risk' labelling: a scoping review

A discussion of the existence, prevalence and characteristics of the nocebo effect in health care.

There is increasing but inconsistent evidence for nocebo effects (the opposite of placebo). Causal mechanisms are believed to be similar to placebo (negative effects result from suggestions of negative clinical outcomes). Risk screening in health care may produce this unintended effect through labelling some patients as high risk. Given health care's almost universal coverage this potentially affects many people.

Discussion paper following a scoping review of the existence and frequency of nocebo.

Literature databases (PsycINFO, MEDLINE, CCTR, CINAHL and EMBASE) searched from inception dates to 2013.

Significant empirical evidence indicates that negative beliefs may impact on health outcomes (incidence estimates range from 3-27%). The nocebo effect, rooted in the complex interplay between physiological functioning and social factors, appears significantly more common among women and where prior negative knowledge or expectations exist. Pre-existing psychological characteristics (anxiety, neuroses, panic disorder or pessimism) exacerbate it.

While the placebo effect is well documented, there has been no systematic attempt to synthesize primary empirical research on the role of nocebo. It is possible that nocebo outcomes may be preventable through careful consideration of information provision and the prior identification of potentially high risk individuals. This paper summarizes the scale and importance of the nocebo effect, its distribution according to a range of social and clinical variables and its known relation to psychological precursors. It identifies important gaps in the research literature.