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Table 1 Enhanced placebo effect and nocebo effect

From: Do randomized clinical trials with inadequate blinding report enhanced placebo effects for intervention groups and nocebo effects for placebo groups? A protocol for a meta-epidemiological study of PDE-5 inhibitors

IIEF-EF change scores   Placebo effects     Treatment effects     
Risk-of-bias domain Number of trials Studies with low risk of bias Studies with unclear or high risk of bias Difference(A) P value (t test) Studies with low risk of bias Studies with unclear or high risk of bias Difference(B) P value (t test) Variability in bias (P value)
Allocation concealment n/N a (95% CI) (IV) b (95% CI) (IV) ba (95% CI)   c (95% CI) (IV) d (95% CI) (IV) dc (95% CI)   
Blinding: participant    
Blinding: caregiver    
Blinding: outcome assessor    
Summary of four risk of bias domains    
  1. CI, confidence interval; IV, inverse variance.