Commentary: Should Preregistration of Epidemiologic Study Protocols Become Compulsory? Reflections and a Counterproposal

There is an ongoing debate regarding preregistration of epidemiologic study protocols. We examine the basic idea that preregistration of study protocols and their associated hypotheses would enhance the reliability of observational research. We define instances in which preregistration would be useful, and we support a counter-proposal: a public registry containing descriptions of collected epidemiologic data. A decision to institute compulsory preregistration of protocols for observational studies—to be enforced by editors and reviewers as sometimes suggested—is not to be taken lightly, and should not be endorsed solely on the basis of an analogous system instituted for randomized trials. Negative reactions toward compulsory registration have been published elsewhere. Note that it is the compulsory preregistration of protocols that is most at issue. There are already mechanisms by which epidemiologists can voluntarily preregister their protocols, if they feel preregistration is advantageous. The open question is whether such preregistration should be required in order for observational research to be published in leading journals (assuming the same “enforcement” mechanism would be adopted as for clinical trials). We examine the validity of the analogy between randomized trials and observational studies with regard to the value of preregistering protocols. We then examine the idea that prespecification of a hypothesis enhances the credibility of results, and that avoidance of “false positives” should always be a primary concern. We discuss research settings when preregistration of an observational study protocol might be of value. Finally, as a counter-proposal, we support the establishment of a public registry of collected epidemiologic data, to include descriptions of the study sample, data elements, and the methods by which the data were collected. Such a registry would better accomplish some of the stated goals of protocol preregistration, such as securing public knowledge about ongoing epidemiologic research and providing a means to identify all potentially available evidence about a research topic.