Clinical Trials

❘❙❚■ Chapter 8 | BlindingAssessing trial blindnessThe degree to which the blinding was maintained in a study can be estimated byasking the patients to guess which group they were assigned to. If the mean resultof the guesses is close to being 50% correct, the study was well blinded. A similarenquiry could be made of the patients’ study investigators also.ConclusionThe blinding of studies requires careful planning and constant monitoring toensure that blinding is maintained, whilst also ensuring that patient safety and thevalidity of trial results are not compromised. Furthermore, it is vital that all studyprotocols clearly document who was blinded in the study and how they wereblinded, as this can have a significant impact on the value of the study results.References1. Pocock SJ. Clinical Trials: A Practical Approach. New York: John Wiley & Sons, 1983.2. Chow SC, Liu JP. Design and Analysis of Clinical Trials: Concepts and Methodologies.New York: John Wiley & Sons, 1998.3. Friedman LM, Furberg CD, DeMets DL. Blindness. In: Fundamentals of Clinical Trials.New York: Springer-Verlag, 1998:82–92.4. Matthews JNS. Assessment, blinding and placebos. In: An Introduction to RandomisedControlled Trials. London: Arnold, 2000:53–9.80