The Federal Coordinating Council for Comparative Effectiveness Research (FCCCER) definition of Comparative Effectiveness Research focuses on studies in "real world" practice; the study designs used for conducting comparative research in practice settings are evolving and at present there are few studies conducted that have wide applicability beyond the settings in which they are based. The purpose of the search strategies presented here is to help inform discussions on or relating to comparative effectiveness by providing retrieval of a full-range of studies on the efficacy-effectiveness-effectiveness in the "real world" continuum. Conceptual organization of these searches has been based on work undertaken by Holve, E. and P. Pittman. A first look at the volume and cost of comparative effectiveness research in the United States [Internet]. Washington, DC: AcademyHealth; 2009 June [cited 2009 Oct. 14]. 20 p.
Clinical effectiveness studies cover a range of study designs with wide variation in terminology and they may be drawn from a variety of data sources. For this reason, the Randomized Controlled Trials and Systematic Review PubMed search strategies have been designed for sensitivity (that is, searches will retrieve many relevant citations but probably a few less relevant ones, too) while the PubMed Observational Studies search strategies have been designed for specificity (that is, searches will retrieve mostly relevant citations but may not include all citations that could be potentially relevant to a particular topic).