title: Searching one or two databases was insufficient for meta-analysis of observational studies.
abstract: OBJECTIVE
  To address methodologic issues in searching for observational studies by presenting database search methods and results.
  
  
  METHODS
  Results of two literature searches for publications reporting on observational studies of alcohol consumption and the risk of breast cancer and large bowel cancer were compared, to evaluate the sensitivity of various bibliographic databases and search strategies, including hand-searching reviews and meta-analyses.
  
  
  RESULTS
  The target sensitivity of 90% of publications in the breast cancer search was achieved by starting with Medline, then adding Biosis, Embase, and SCI EXPANDED-SSCI, which provided a total of 72 (91%) of the 79 relevant publications. To reach a similar 89% sensitivity for large bowel cancer, at least Biosis, Dissertation Abstracts Online, Embase, ETOH, and Medline had to be searched, with the addition of hand search of reviews and meta-analyses.
  
  
  CONCLUSIONS
  Limiting a search to one or two databases when conducting meta-analyses of observational studies will not provide a thorough summary of the existing literature. The findings support recommendations to implement a comprehensive search of electronic databases and the reference lists of recent review articles and meta-analyses.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Adina R
authors.initials: AR
authors.lastname: Lemeshow
authors.forename: Robin E
authors.initials: RE
authors.lastname: Blum
authors.forename: Jesse A
authors.initials: JA
authors.lastname: Berlin
authors.forename: Michael A
authors.initials: MA
authors.lastname: Stoto
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
mesh_terms: D000428:Alcohol Drinking / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology; D016206:Databases, Bibliographic; D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000453:epidemiology; D007420:Intestine, Large; D016239:MEDLINE; D015201:Meta-Analysis as Topic; D011642:Publications; D012307:Risk Factors