When Is Evidence Sufficient?

Emerging Lessons From The Drug Effectiveness Review Project

The Drug Effectiveness Review Project (DERP) is an alliance of fifteen states and two private organizations, which have pooled resources to synthesize and judge clinical evidence for drug-class reviews. The experience shines a bright light on challenges involved in implementing an evidence-based medicine process to inform drug formulary decisions: When should evidence reviewers accept surrogate markers and assume therapeutic class effects? How open and participatory should review procedures be? Should reviewers consider cost-effectiveness information? What is the appropriate role of the public sector in judging evidence? The DERP illustrates that attempts to undertake evidence-based reviews, apart from the methods themselves, which continue to evolve, involve questions of organization, process, and leadership.

Evidence-based medicine in pathology: an introduction

Evidence-based medicine (EBM) is a school of thought that has spread rapidly through medicine in the past 2 decades and is eliciting an increasing interest in Anatomic Pathology and Laboratory Medicine. It has been defined as "the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients." The environmental factors that created a need for EBM and basic concepts of this discipline are reviewed. Methods for the accrual and critical appraisal of the validity of available evidence and its impact, applicability and usefulness in pathology practice are discussed. Basic concepts of bayesian data analysis with an emphasis on concepts such as prior and posterior probability and the use of "holdout" or "test" data are introduced. The future of EBM in pathology is discussed and potential applications of these concepts to pathology practice and research are proposed.

The application of special technologies in diagnostic anatomic pathology: is it consistent with the principles of evidence-based medicine?

Proponents of evidence-based medicine (EBM) have emphasized the need to consider the quality of different sources of medical information and have proposed various methods to integrate available "best evidence" into rules, guidelines and other diagnostic, therapeutic and prognostic models. The various factors that can affect the internal validity of studies in anatomic pathology, such as interobserver variability, use of retrospective rather than prospective data and others, are reviewed. The need for testing for the external validity of the results of anatomic pathology studies is introduced, using "test sets" of cases that have not been used to generate the classification or prognostic models. This methodology has been seldom used in anatomic pathology to validate the generalizability of various "entities," usefulness of diagnostic tests under different conditions and other information. Basic concepts of meta-analysis for research synthesis are introduced; these methods have been seldom used in anatomic pathology to integrate information from different studies using quantitative techniques rather than summary tables that merely list the results of various publications. The potential use of decision analysis and value of information analysis for the adoption of new tests is briefly discussed.