Searching for high-quality articles about intervention studies in occupational health - what is really missed when using only the Medline database?

Objective Most occupational health physicians access electronic databases to obtain reliable medical information. Although it has been demonstrated that the use of Medline alone does not ensure comprehensiveness, many experts rely solely on this database. Our study aimed to discover to what extent the physician who limits his/her search to Medline misses studies of high quality. Methods We constructed a "gold standard" database of high-quality intervention studies gathering all the references included in the systematic reviews of the Cochrane Library and indexed under the topic "occupational health field". We then searched all these references, one by one, in Medline. Results Overall, 88.8% [95% confidence interval (95% CI) 86.1-91.5] of the high quality studies included in our gold standard database were indexed in Medline. References included in reviews on psychiatric or psychological topics were significantly less often indexed in Medline [81.7% (95% CI 75.9-88.5)] than references included in reviews on other topics [92.2% (95% CI 89.5-95.0)] (P=0.001). Conclusion The recall ratio of Medline for high-quality intervention studies is close to 90%. For occupational health practitioners who aim to find reliable answers to their daily practice questions, searching Medline only is more cost-effective than previously thought.