Generalizability of systematic reviews of the effectiveness of health care interventions to primary health care: Concepts, methods and future research

Background: There is a push to make clinical decision making more evidence based and patient oriented. However, current systematic reviews are limited by the lack of consideration of generalizability. Objective: To develop a guide for investigators (systematic reviewers) on how to adapt the methodology of a systematic review to facilitate the exploration of the results to primary care. Methods: We reviewed the method guidelines of five organizations and working groups. Then, we conducted a search of literature in PubMed for articles on external validity of systematic. Based on the literature, we developed general steps to incorporate generalizability in systematic reviews and then integrated main primary care themes as outlined in WONCA definition of primary care and the definition of person-centred medicine across those steps. Results.: We identified a wide variety of approaches to address the issue of generalizability in systematic reviews. We extracted four major primary care themes from the two definitions of primary care and person-centred medicine that we mapped across the methods of generalizability. We suggested a two-step approach: Step 1 planning the scope of a review using four-layer schematic model and Step 2 to follow four steps to incorporate the concept of generalizability to primary care in the review. Conclusions: Systematic reviewers can take several steps to improve the generalizability of their review to primary care. However, more research is needed to determine which approach provides better results than others.