Searching for systematic reviews of the effects of social and environmental interventions: a case study of children and obesity.

SETTING: Although an important part of the evidence base in health, systematic reviews are not always easy to find. Difficulties are compounded when interventions under review are "social and environmental" (that is, targeting wider determinants of health). The authors explored searches from a descriptive map containing thirty-two systematic reviews evaluating the effectiveness of social and environmental interventions for childhood obesity. QUESTIONS: Which sources give the highest yield of relevant reviews per 100 records? What is the value of searching databases that index literature beyond the "health" arena when looking for data on the effectiveness of social and environmental interventions? METHODS: The authors analyzed search results from nineteen databases and calculated the precision and the relative and unique contribution of each source. RESULTS: Searches of specialist systematic review databases-Database of Abstracts of Reviews of Effects (DARE), Database of Promoting Health Effectiveness Reviews (DoPHER), and Health Technology Assessment (HTA)-had the highest precision, although MEDLINE, CINAHL, and PsycINFO located many additional reviews. The Cochrane Database of Systematic Reviews should be searched for health-related reviews. Searches of education, transportation, social policy, and social sciences databases did not identify additional reviews. Searching websites and bibliographies was important. CONCLUSIONS: Searches for review-level evidence could profitably start with the specialist review databases. Searches of the major health-related databases are essential, but database searching beyond them may not identify much additional evidence. Internet and hand-search remain important sources of reviews not found elsewhere. Comparison of the results with previous research suggests that appropriate sources for locating primary and secondary evidence may be different.