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Table 1 Definitions of major placebo reactions (MPR) at DBPCFC with examples

From: Standardization of double blind placebo controlled food challenge with soy within a multicentre trial

Type of major placebo reaction (MPR) Definition according to signs or symptoms elicited by placebo challenge meal Example for reaction elicited by placebo challenge meal Dose level/VASplacebo Example for reaction elicited by
Soy challenge meal
Dose level/VAS
Objective Any ObjS (O1-10, attributable to the DBPCFC) Any Any or none
Any ObjS (O1-10, not clear if being attributable to the DBPCFC
i.e. single wheal) at a lower dose level compared to soy
5 or below 6
Subjective Any single SubjS* (S1–8) at lower dose level compared to soy 5 or below/any VASplacebo * 6/any VASsoy *
Single* Any single SubjS* (S1–8) at same dose level like any single SubjS* to soy 5/any VASplacebo * 5/any VASsoy *
Single** Any single SubjS** (S1–8) at same dose level like any single SubjS to soy and no difference of at least 2 cm in favor of soy 4/any VASplacebo **
(e.g. 0.6 cm)
4/any VASsoy ***
< VAS*** placebo -2 cm
(e.g. 2 cm)
Sum type*** Two or more aggregated SubjS** (S1–10) and two or more aggregated SubjS** (S1–8) to soy (any but same dose level for both)
and no difference between sum VAS values of at least 2 cm in favor of soy
5/any sum VASplacebo ***
(e.g. 4 cm)
5/any sum VASsoy ***
< sum VASplacebo ***-2 cm
(e.g. 5 cm)
  1. ObjS objective signs, SubjS subjective symptoms, VAS soy /VAS placebo visual analogue scale value at soy/placebo challenge in cm
  2. * Single VAS of at least 1.5 cm
  3. ** Single VAS of at least 0.5 cm
  4. *** Sum of VAS values of at least 0.5 cm, e.g.—example given