In this essay, we defend the design of the Salk polio vaccine trial and try to put some limits on the role schemata should play in designing clinical research studies. Our presentation is structured as a response to de Freitas and Pietrobon who identified the CONSORT statement as a schema that would have, had it existed at the time, ruled out the design of the Salk polio vaccine trial of 1954 in favor of a completely randomized controlled clinical trial. We (...) argue that large-scale public health interventions often require evidence beyond simple efficacy, the limit of what an RCT can provide, and that the design actually adopted for the Salk trial represented a reasonable—albeit imperfect—compromise. This is of more than historical interest in that many contemporary studies are of the scale and scope to require a more pragmatic, rather than explanatory, approach to study design. (shrink)

Introduction: Clinical practice guidelines (CPGs) are an important source of justification for clinical decisions in modern evidence-based practice. Yet, we have given little attention to how they argue their evidence. In particular, how do CPGs argue for treatment with long-term medications that are increasingly prescribed to older patients? Approach and rationale: I selected six disease-specific guidelines recommending treatment with five of the medication classes most commonly prescribed for seniors in Ontario, Canada. I considered the stated aims of these CPGs and (...) the techniques employed towards those aims. Finally, I reconstructed and logically analysed the arguments supporting recommendations for pharmacotherapy. Analysis: The primary function of CPGs is rhetorical, or persuasive, and their means of persuasion include both a display of their credibility and their argumentation. Arguments supporting pharmacotherapy recommendations for the target population follow a common inductive pattern: statistical generalization from randomized controlled trial (RCT) and meta-analysis evidence. Two of the CPGs also argue their treatment recommendations for older patients in this style, while three fail to justify pharmacotherapy specifically for the older population. Discussion: The arguments analysed lack the auxiliary assumptions that would warrant making a generalization about the clinical effectiveness of medications for the older population. Guidelines reason using simple induction, while ignoring important inferential gaps. Future guidelines should aspire to be well-reasoned rather than simply evidence-based; argue from a plurality of evidence; be wary of hasty inductions; appropriately limit the scope of their recommendations; and avoid making law-like, prescriptive generalizations. (shrink)