To the Editor.
—In contrast to the view of Drs Freemantle and Drummond,1 I have never seen a distinction between "efficacy" and "effectiveness" trials that holds up to "realworld" testing. The ideal world—real world dichotomy seems initially attractive, but classifying actual trials by this criterion has been difficult. The same is true for the distinction that Schwartz and Lellouch2 make between explanatory and pragmatic trial designs. These notions become little more than mere assertions of how someone would like things to be.Many trials designed to demonstrate treatment differences in efficacy also have successfully simulated the real world of therapeutics. Trials with only clinical end points could arbitrarily be called "efficacy trials," and those that also use economic end points could be called "effectiveness trials," but then why not simply call these studies "clinical" and "clinical/ economic" trials? However, no trial will attain 100% fidelity with the real
Johnson K. Blinding of Clinical Trials With Concurrent Economic Analysis. JAMA. 1997;277(21):1677. doi:10.1001/jama.1997.03540450033017