An evaluation of search and selection methods used in dental systematic reviews published in English.

BACKGROUND: Increasing numbers of systematic reviews are published each year, though little has been done to evaluate their search and selection methodology.
METHODS: The authors searched dental systematic reviews published between Jan. 1, 2000, and July 14, 2005, for descriptions of how researchers used multiple electronic databases and secondary searches. They evaluated search and selection methods of identified systematic reviews against the guidelines found in the 2005 Cochrane Handbook for Systematic Reviews of Interventions.
RESULTS: The authors identified 220 unique dental systematic reviews. They found that all aspects of search and selection methodology had improved. In 2005, most systematic reviews documented database names and search dates (90 percent), electronic search terms (95 percent) and inclusion-exclusion criteria (95 percent), and most employed secondary searching (100 percent). Many still failed to search more than MEDLINE (20 percent), document the search strategy (20 percent), use multiple reviewers for selecting studies (25 percent) and include all languages (39 percent). CONCLUSIONS AND CLINICAL IMPLICATIONS: Systematic review methodology is improving, though key components frequently are absent. Reviews should be read critically and in consideration of the methodological flaws.