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%, j = 0.80, p < 0.001) for SHAM grades 0-4 increased to 100% following discussion between assessors. More than half of the randomised controlled study designs subjected patients in control groups to risks of serious or irreversible harm. A debate on whether it is justifiable to expose control group patients to risks of serious harm is overdue.

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Williams syndrome is a genetic disorder associated with cardiac pathology, including supravalvular aortic stenosis and coronary artery stenosis. Sudden cardiac death has been reported in the perioperative period and attributed to cardiovascular pathology. In this retrospective audit, case note and anaesthetic records were reviewed for all confirmed Williams syndrome patients who had received an anaesthetic in our institution between July 1974 and November 2009. There were a total of 108 anaesthetics administered in 29 patients. Twelve of the anaesthetics (11.1%) were associated with cardiac complications including cardiac arrest in two cases (1.85%). Of the two cardiac arrests, one patient died within the first 24 hours postanaesthetic and the other patient survived, giving an overall mortality of 0.9% (3.4%). We conclude that Williams syndrome confers a significant anaesthetic risk, which should be recognised and considered by clinicians planning procedures requiring general anaesthesia.

SummaryThe SHAM (Serious Harm and Morbidity) scale was developed to categorise the severity of potential complications of placebo control interventions in the context of local anaesthesia research. A convenience sample of 43 anaesthetists used the SHAM scale to grade ten published randomised controlled trials investigating local anaesthesia nerve blocks. The Fleiss j statistic assessed agreement between these anaesthetists and probability of random agreement (Pr(e)) when using the SHAM scale; a j > 0 shows concordance between assessors above random agreement. Overall j was 0.50 (95% CI 0.49-0.51, p < 0.001), Pr(e) = 0.21. There was moderate agreement between assessors in determining whether studies were low-risk (SHAM score 0-2) or high-risk (SHAM score 3-4) (j 0.60 (95% CI 0.58-0.62), Pr(e) = 0.51). Compared with anaesthetists given clinical examples of interventions when applying the SHAM score, anaesthetists who were not given examples showed significantly less inter-individual agreement (j 0.76 (95% CI 0.72-0.81), Pr(e) = 0.5 vs 0.45 (95% CI 0.41-0.49), Pr(e) = 0.52, p < 0.0001). These results suggest that the SHAM score can be successfully used to grade the severity of potential complications of placebo-controlled interventions in local anaesthesia research and represent a first step towards the score's validation.