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Letters |

Evaluating Clinical Studies of Drug Efficacy—Reply

Finlay McAlister, MD; Andreas Laupacis, MD, MSc; George Wells, MSc, PhD; David Sackett, MD
JAMA. 2000;283(9):1139-1140. doi:10.1001/jama.283.9.1137.
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In Reply: The levels of evidence we proposed were designed to help inform debates about class effects, not censor them, and as such we did not define any cutoff between "acceptable" and "unacceptable" evidence. In doing so, we recognize that reasonable individuals may disagree about how to interpret the same evidence; however, at least our proposed hierarchy would provide a framework for the debate.

Although we are aware of the recent innovations in observational study designs alluded to by Dr Donnan and colleagues, we are concerned about the progressive distortions in efficacy estimates that occur as we move from RCTs with concealed allocation to RCTs with open allocation to observational studies.1 As such, we believe that RCTs (and particularly head-to-head RCTs) remain the evidentiary standard by which interventions should be evaluated and compared.


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