Читать книгу Randomised Clinical Trials - David Machin - Страница 53

In a randomised controlled trial conducted by Chow, Tai, Tan, et al. (2002) in advanced liver cancer, patients were randomised to receive either placebo (P) or tamoxifen (T). Tamoxifen, although not anticipated to influence survival outcome, was often used to palliate symptoms in such patients although no randomised trial had been conducted to measure its effectiveness, and this provided the rationale for the use of a placebo.

However, placebo controls and no‐treatment controls are not possible in many circumstances. In which case, the control group may comprise those receiving current best practice. For example, in patients receiving surgery for the primary treatment of head and neck cancer followed by best supportive care, a randomised controlled trial may be assessing the value of adding postoperative chemotherapy to this standard (best supportive care only) approach. In this case, the control group are those who receive the current standard of no adjuvant treatment, whilst the test group receive chemotherapy in addition. In some situations, the no intervention control may be a watch‐and‐wait policy, whilst the comparator group receives an immediate intervention.