Intended for healthcare professionals


Optimal search strategies for retrieving scientifically strong studies of diagnosis from Medline: analytical survey

BMJ 2004; 328 doi: (Published 29 April 2004) Cite this as: BMJ 2004;328:1040
  1. R Brian Haynes, professor (bhaynes{at},
  2. Nancy L Wilczynski, research associate

    Hedges Team

  1. 1Health Information Research Unit, Department of Clinical Epidemiology and Biostatistics, McMasterUniversity Faculty of Health Sciences, 1200 Main Street West, Hamilton, ON, L8N 3Z5, Canada
  1. Correspondence to: R B Haynes
  • Accepted 18 March 2004


Objective To develop optimal search strategies in Medline for retrieving sound clinical studies on the diagnosis of health disorders.

Design Analytical survey.

Setting Medline, 2000.

Participants 170 journals for 2000 of which 161 were indexed in Medline.

Main outcome measures The sensitivity, specificity, precision (“positive predictive value”), and accuracy of 4862 unique terms in 17 287 combinations were determined by comparison with a hand search of all articles (the “gold standard”) in 161 journals published during 2000 (49 028 articles).

Results Only 147 (18.9%) of 778 articles about diagnostic tests met basic criteria for scientific merit. Combinations of search terms reached peak sensitivities of 98.6% at a specificity of 74.3%. Compared with best single terms, best multiple terms increased sensitivity forsound studies by 6.8% (absolute increase), while also increasing specificity (absolute increase 6.0%) when sensitivity was maximised. When terms were combined to maximise specificity, the singleterm, (98.4%), outperformed combinations of terms. The strategies newly reported in this paper outperformed other validated search strategies except for one strategy that had slightly higher sensitivity (99.3% v 98.6%) but lower specificity (54.7% v 74.3%).

Conclusion New empirical search strategies in Medline can optimise retrieval of articles reporting high quality clinical studies of diagnosis.


  • Contributors RBH planned the study, designed the protocol, and interpreted the data; he will act as guarantor. NLW supervised the research staff, and collected, analysed, and interpreted thedata. The Hedges Team conducted the study: AE, SM, AM, CW-D, S Werre, and S Wong collected the data. DM programmed the data set and analysed the data. S Walter and S Werre provided statistical advice, and S Werre did supplementary analyses. The manuscript was prepared by NLW and RBH.

  • Funding This study was funded by the US National Institutes of Health (grant No 1 RO1 LM06866).

  • Competing interests None declared.

  • Ethical approval: Not required.

  • Accepted 18 March 2004
View Full Text