Editorial :: VIEWPOINT: Randomised controlled trials using invasive ‘placebo’ controls are unethical and should be excluded from Cochrane Reviews - The Cochrane Library

"Placebo controls are frequently used to ‘blind’ participants, trial personnel and outcome assessors to intervention and control in clinical trials. Effective blinding of treatment reduces the risk of performance bias (differences between groups in the care provided apart from the intervention being evaluated) and detection bias (differences between groups in how outcomes are ascertained, diagnosed or verified). A placebo has traditionally been defined as an “inert or innocuous substance”,[1] such as a ‘sugar pill’. However, some randomised controlled trials (RCTs) have been shown to erroneously use the term ‘placebo’ to describe an invasive intervention that exposes participants, allocated to a control group, to risks of serious harm.[2,3] In this context therefore, the term ‘placebo’ describes an invasive intervention which is neither inert nor innocuous.
In a recent study of local anaesthesia RCTs, over half the RCTs used an invasive ‘placebo’ control.[2] The ‘placebo’ interventions mostly involved deep-needle insertion through body tissues with potential damage to nerves, vessels and other structures such as liver and bowel. These interventions exposed control group participants to risks of serious morbidity.[2,3].......