FORMULATING QUESTIONS AND LOCATING PRIMARY STUDIES FOR INCLUSION IN SYSTEMATIC REVIEWS

Much time and effort are spent on designing primary research studies. Similar care must be given to planning systematic reviews. The review should be based on an important, well-focused question that is relevan t to patient care. By formulating the question properly, the criteria that primary studies must meet to be included in the review become cle ar. These criteria, which comprise the types of persons involved, expo sure, control group, outcomes, and study designs of interest, can then be refined so that they are clinically relevant, sensible, and workab le. Inclusion criteria that are too narrow will limit the amount of da ta in the review, thereby increasing the risk for chance results and m aking the review less useful for the reader. Reviews should include st udies whose designs offer the least biased answer to the question bein g asked. To maximize available data and reduce the risk for bias, as m any relevant studies as possible need to be identified, regardless of publication status or language. Multiple overlapping search strategies should therefore be used and must be carefully planned. Strategies in clude searching the many electronic databases available (after careful consideration of which terms to enter), manually searching journals a nd conference proceedings, searching bibliographies of articles, searc hing existing registers of studies, and contacting companies or resear chers. The time taken to formulate the question adequately and develop appropriate searches will increase the chance of producing a high-qua lity, meaningful review.