Beyond MEDLINE for literature searches

Purpose: To describe strategies for a comprehensive literature search. Organizing Construct: MEDLINE searches result in limited numbers of studies that are often biased toward statistically significant findings. Diversified search strategies are needed. Methods: Empirical evidence about the recall and precision of diverse search strategies is presented. Challenges and strengths of each search strategy are identified. Findings: Search strategies vary in recall and precision. Often sensitivity and specificity are inversely related. Valuable search strategies include examination of multiple diverse computerized databases, ancestry searches, citation index searches, examination of research registries, journal band searching, contact with the "invisible college," examination of abstracts, Internet searches, and contact with sources of synthesized information. Conclusions: Extending searches beyond MEDLINE enables researchers to conduct more systematic comprehensive searches.