Evidence-based research.

In recent years, increasing emphasis has been placed on improving the quality of medical literature. Many journals in otolaryngology and other medical disciplines are skewing their editorial-selection process toward reporting evidence-based research classified as "strong." In addition, many journals are moving toward publishing evidence classification of articles, and of references cited in articles, to help the reader evaluate the information. Therefore, to better assess and improve the quality of published manuscripts, otolaryngologists should be familiar with the current standards and classification of research.

Evidence-based research is rated from Class I to Class IV. In Class I clinical research, evidence is provided through a blinded, prospective study including a broad spectrum of patients with a suspected condition and using a "gold standard" for case definition. Class II evidence may be provided through a prospective study that includes a narrower spectrum of subjects with the suspected condition, or through a well-designed retrospective study including a broad spectrum of subjects with a condition established by a "gold standard." These subjects are compared with a broad spectrum of controls, with the test that is being evaluated applied in a blinded fashion.

In Class III studies, evidence is acquired retrospectively, either using a narrow spectrum of subjects who have the established condition or retrospective controls, but in which the test or topic under investigation is still applied in a blinded fashion. Class IV includes any study design in which the test under investigation is not applied in a blinded evaluation, or in which evidence is provided by descriptive case series without controls or by expert opinion alone.

Although the value of scientifically valid and reliable publications is self-evident, this editor believes that there is still a place for papers that do not meet the criteria for Class I or II evidence-based research. For example, case reports, qualitative research, scholarly reviews, and other similar articles may be extremely valuable educational contributions to the literature. Nevertheless, high-quality, evidence-based research provides a desirably high level of comfort for the reader and editorial board with regard to a paper's validity. Often, it is almost as easy to perform high-quality, evidence-based research as it is to perform a study that does not meet such rigorous standards; but, too often, investigators do not consider research design carefully enough before performing a study.

Clearly, articles that achieve a Class I or II rating are more credible than many other articles. While we should not exclude from publication articles that do not meet these criteria, the increased rigor they ensure is compelling; and we should make every effort to increase the percentage of articles published in the otolaryngology literature that meet the highest standards of validity and reliability.