Cochrane Summaries

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New treatments versus established treatments in randomized trials

Djulbegovic B, Kumar A, Glasziou PP, Perera R, Reljic T, Dent L, Raftery J, Johansen M, Di Tanna GL, Miladinovic B, Soares HP, Vist GE, Chalmers I
Published Online: 
17 October 2012

Random allocation to different groups to compare the effects of treatments is used in fair tests to find out which among the treatment options is preferable. Random allocation is only ethical, however, if there is genuine uncertainty about which of the treatment options is preferable. If a patient or their healthcare provider is certain which of the treatments being compared is preferable they should not agree to random allocation, because this would involve the risk that they would be assigned to a treatment they believed to be inferior. Decisions about whether to participate in randomized trials are made more difficult because of the widespread belief that new treatments must inevitably be superior to existing (standard) treatments. Indeed, it is understandable that people hope that this will be the case. If this was actually so, however, the ethical precondition of uncertainty would often not apply. This Cochrane methodology review addresses this important question: "What is the likelihood that new treatments being compared to established treatments in randomized trials will be shown to be superior?" Four cohorts of consecutive, publicly funded, randomized trials, which altogether included 743 trials that enrolled 297,744 patients, met our inclusion criteria for this review. We found that, on average, new treatments were very slightly more likely to have favorable results than established treatments, both in terms of the primary outcomes targeted and overall survival. In other words, when new treatments are compared with established treatments in randomized trials we can expect slightly more than half will prove to be better, and slightly less than half will prove to be worse than established treatments. This conclusion applies to publicly funded trials as we did not include studies funded by commercial sponsors in our analysis.The results are consistent with the ethical preconditions for random allocation – when people are enrolled in randomized trials, the results cannot be predicted in advance as there is genuine uncertainty about which of the treatments being compared in randomized trials will prove to be superior. 

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