IDEAL framework for surgical innovation 2: observational studies in the exploration and assessment stages

The IDEAL framework describes the stages of evaluation for surgical innovations. This paper considers the role of observational studies in the exploration and assessment stages. At the exploration stage, the surgical intervention is usually more widely used, and observational studies should collect prospective data from multiple surgeons, deal with factors such as case mix and learning, and prepare for a de nitive evaluation at the next stage of assessment. Although a randomised controlled trial is preferable, a high quality observational study would be acceptable if a randomised trial is not feasible or, on rare occasions, deemed unnecessary. Introduction The evaluation of new innovations, from idea developed to accepted practice, has been less orderly in surgery and other interventional therapies than in clinical pharma-cology. The IDEAL framework for surgical innovations and recommendations has been designed to describe the stages of evaluation for these interventional therapies (idea, development, exploration, assessment, and long term study), and to highlight the study designs and reporting standards that are likely to prove most useful at each stage. The rst two IDEAL stages are covered in the rst paper in this series. This second article focuses on the IDEAL recommendations for the use of observational studies in the exploration and assessment stages, and discusses the options for observational study designs and reporting protocols (box), using examples of surgical innovations. The nal paper in the series covers the undertaking of a de nitive randomised controlled trial, mainly in the assessment stage, as well as the long term stage.