A key component to a successful systematic review involves conducting a comprehensive, thorough literature search. The idea behind doing a methodical search is to be as comprehensive as possible when looking for relevant literature. This helps ensure you don’t miss any potentially useful articles.
Depending on your topic, you may need to search a number of different databases, trials registries, websites, and so on. Other methods include citation tracking, contacting study investigators, experts, and manufacturers. You may also engage in something called, “hand-searching”, which requires you to comb through the reference lists of selected journals for articles that may have been missed in your original database search.
How Many Results are Enough?
This question is frequently asked when conducting searches in support of systematic review topics.
As can be seen in the table below, the numbers of resulting search citations is completely topic dependent, and cannot be established prior to the searching.
| Systematic Review Article | Search Results | Total Used |
| Atenstaedt and Jones 2011 | 68 | 0 |
| Dennis, Hawken et al. 2011 | 365 | 38 |
| Leufkens, van den Bosch et al. 2011 | 779 | 11 |
| Carroll, Papaioannou et al. 2011 | 1,444 | 4 |
| Ford, Khan et al. 2011 | 3,061 | 44 |
| Evans, Watson et al. 2011 | 4,142 | 40 |
| McGinn, Grenier et al. 2011 | 5,695 | 117 |
| Neelam, Garg et al. 2011 | 8,678 | 7 |
| Irwin, Yoon et al. 2011 | 9,760 | 19 |
| Dickens and Picchioni 2012 | 13,765 | 11 |
| Clegg and Young 2011 | 18,767 | 14 |
| Chowdhury, Dagash et al. 2007 | 55,391 | 163 |
| do Prado, Piovesan et al. 2010 | 68,528 | 12 |
Please see the following link to a brief document that highlights guidance methodologies that recommend the involvement of information specialists or librarians in systematic reviews:
