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Forty years after the introduction of the randomised trial to assess the effectiveness of streptomycin for the treatment of tuberculosis, new drugs cannot gain clinical acceptance or regulatory approval without being tested in randomised trials. This experience has resulted in the general impression that new procedures and techniques must be validated similarly. In regard to coronary bypass surgery Hiatt suggested that “well designed trials should precede widespread dissemination, as is done to a considerable extent for drugs.”1
That recommendation reveals misconceptions about the differences between trials of new drugs and trials of new procedures. Indeed, with interventional procedures becoming ever more important in the treatment of cardiovascular disorders, discussions that once seemed pertinent only to surgical therapy are now pertinent to interventional cardiovascular treatment as well.
Drugs versus procedures
Table 1 lists several obvious differences between drugs and procedures. Drugs have an unchanging composition, but as drug use increases, additional side effects and complications become apparent. When used in a trial, a drug’s effectiveness is unrelated to the physician’s skill; not only are results generally consistent among collaborating institutions, but they are also applicable to non-participating institutions. Finally, a placebo is usually available, and crossover between treatment groups is exceptional.
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Obvious differences between randomised trials for drugs and procedures
In contrast, new procedures are introduced while they are imperfect. The indications are uncertain and the risks are high. As the procedure becomes more widespread, refinements occur and the risks decline, …