Use of invasive placebos in research on local anaesthetic interventions

摘要

Placebos play a vital role in clinical research, but their invasive use in the context of local anaesthetic blocks is controversial. We assessed whether recently published randomised controlled trials of local anaesthetic blocks risked harming control group patients in contravention of the Declaration of Helsinki. We developed the ‘SHAM’ (Serious Harm and Morbidity) scale to assess risk: grade 0?=?no risk (no intervention); grade 1?=?minimal risk (for example, skin allergy to dressing); grade 2?=?minor risk (for example, subcutaneous haematoma, infection); grade 3?=?moderate risk (with or without placebo injection) (for example, neuropraxia); and grade 4?=?major risk (such as blindness, pneumothorax, or liver laceration). Placebo interventions of the 59 included trials were given a SHAM grade. Nine hundred and nineteen patients in 31 studies, including six studies with 183 children, received an invasive placebo assessed as SHAM grade ≥?3. A high level of agreement (78%, κ?=?0.80, p?