Assessment of a novel blinding device for nerve catheter studies: a randomised ex vivo study

Editor—Unblinded studies overestimate treatment effects compared with blinded studies. 1 Schulz K.F. Chalmers I. Hayes R.J. Altman D.G. Empirical evidence of bias: dimensions of methodological quality associated with estimates of treatment effect in controlled trials. JAMA. 1995; 273: 408-412 Google Scholar , 2 Poolman R.W. Struijs P.A.A. Krips R. et al. Reporting of outcomes in orthopaedic randomized trials: does blinding of outcome assessors matter?. J Bone Joint Surg Am. 2007; 89: 550-558 Google Scholar , 3 Furberg C.D. Soliman E.Z. Double-blindness protects scientific validity. J Thromb Haemost. 2008; 6: 230-231 Google Scholar Therefore, blinding participants and outcome assessors is an important aspect of study design to minimise potential bias. Blinding is particularly important for studies involving subjective outcomes such as pain, satisfaction, or quality of recovery, which are commonly assessed outcomes in studies investigating the efficacy of regional anaesthesia techniques. However, blinding is particularly difficult to achieve in procedure-related research when compared with pharmaceutical research. 4 Monaghan T.F. Agudelo C.W. Rahman S.N. et al. Blinding in clinical trials: seeing the big picture. Medicina. 2021; 57: 647 Google Scholar ,5 Karanicolas P.J. Farrokhyar F. Bhandari M. Blinding: who, what, when, why, how?. Can J Surg. 2010; 53: 345-348 Google Scholar Despite its importance as a scientific principle, the success or failure of blinding is frequently not assessed. Furthermore, when it is assessed, it has been consistently demonstrated that blinding is often not achieved in practice. 1 Schulz K.F. Chalmers I. Hayes R.J. Altman D.G. Empirical evidence of bias: dimensions of methodological quality associated with estimates of treatment effect in controlled trials. JAMA. 1995; 273: 408-412 Google Scholar ,2 Poolman R.W. Struijs P.A.A. Krips R. et al. Reporting of outcomes in orthopaedic randomized trials: does blinding of outcome assessors matter?. J Bone Joint Surg Am. 2007; 89: 550-558 Google Scholar ,6 Fergusson D. Cranley K.C. Wating D. Shapiro S. Turning a blind eye: the success of blinding reported in a random sample of randomised, placebo controlled trials. BMJ. 2004; 21: 328-432 Google Scholar ,7 Webster R.K. Bishop F. Collins G.S. et al. Measuring the success of blinding in placebo-controlled trials: should we be so quick to dismiss it?. J Clin Epidemiol. 2021; 135: 176-181 Google Scholar