Fig 1.
Flow diagram of patient’s enrollment.
Table 1.
Demographic and clinical characteristics for different groups.
Table 2.
Results of the ANOVA (factors time: Pre/post treatment, placebo pills: Yes/no, expectancy briefing: Detailed information on placebos / no detailed information; depending variables: Composite symptom scores, physical and mental sum scores of the SF-36) significant results in bold, no other significant results were found).
Fig 2.
Changes of allergic symptoms for open-label placebo and control group (mean and standard error).
Patients indicated their response on a seven-point scale ranging from ‘never’ (1) to ‘always’ (7) (composite score of all symptoms). Results demonstrate significantly stronger improvement for the open-label placebo group relative to the control group. * p = 0.02.
Fig 3.
Data of the allergic diary demonstrate improvement of the open-label placebo group over time.
Table 3.
Treatment outcomes (pre, post, and change scores).
Fig 4.
Changes of allergic symptoms for open-label placebo and control group for single symptom groups (mean and standard error).
Results show significant improvements for the open-label placebo group but not for the control group. * p < 0.05, (*) p = 0.06.
Fig 5.
Change of mental or emotional quality of life (mental sum score of the SF-36) when receiving detailed information on placebos (raising positive expectancies) compared with no detailed information about the power of placebos.
Results revealed stronger improvement of mental or emotional quality of life when being told that placebos are powerful (irrespective of receiving open-label placebos).