TABLE 2.

Mediators and moderators of the placebo response in RCT in inflammatory bowel diseases (IBD) and the irritable bowel syndrome (IBS) and other functional gastrointestinal disorders, as evidenced (yes) in this and in previous reviews (e.g. Enck and Klosterhalfen 2020); question marks indicate a lack of knowledge.

IBD	Mediators/Moderators	IBS
Patient Factors
?	age	yes
?	sex/gender	yes
?	personality	yes
?	race/culture	?
?	proxies	?
Disease Factors
yes	severity of disease	yes
yes	duration of disease	yes
yes	previous treatments	yes
yes	concomintant therapies	?
yes	route of administration	?
Design Factors
yes	No of study visits	yes
yes	No of study centers	yes
?	No of patients	yes
yes	Duration of RCT	yes
Therapist Factors
?	Therapist (age, sex)	?
?	Clinical setting	yes
?	Health care system	?
yes	Nationality	yes
?	Culture	yes