The clinical relevance of observational research.

In recent years there has been much discussion of evidence based medicine and of the importance of randomised controlled trials. It may appear that observational research is a lesser method of inquiry, belonging to darker times before the dawn of this new paradigm. In this review we aim to describe to the practising emergency physician the current relevance of observational research within an evidence based medicine framework. This will be done by defining the meaning of the term "observa- tional study" and examining the nomenclature of observational methodologies (excepting qualitative research). The types of information provided by the different methodologies will be identified by using, where possible, examples from published studies in emergency medi- cine. There will be a particular emphasis on how observational studies can describe the performance of diagnostic tests. Finally we will discuss the limitations of observational research before concluding how this form of study can inform the clinical management of accident and emergency (A&E) patients