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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