Search Strategies for OVID
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Sensitivity and Specificity
Methodologic Filters

Sensitivity and Specificity:   In searching, these two terms are analogous to the way they are used in diagnosis. Sensitivity is the proportion of all the relevant articles in Medline that your search manages to retrieve. Specificity is the proportion of articles which you retrieve which are relevant.

Put another way:

Sensitivity is the likelihood of retrieving all the relevant articles;
Specificity is the likelihood of excluding all the irrelevant articles.

If you're search yields an unmanageably large number of hits, you need to increase the specificity of your search; conversely, if you get too small a number of hits, you need to increase sensitivity.

To increase sensitivity (ie, to include more relevent articles):

1. Broaden your question,
2. find more search terms from relevant records,
3. try different cobinations of terms,
4. use truncation ($) or wildcard (?) in either Title Word or Keyword  search terms,
5. combine terms of related meaning using OR ,
6. use a combination of Title Word and Keyword  searches,
7. use the explosion feature of Keyword  searches,
8. select All Subheadings with Keyword terms, or
9. search further back in time.

To increase specificity (ie, to exclude irrelevent articles):

1. Narrow your question,
2. use more specific terms in a Title Word search,
3. use a Keyword  search rather than Title Word search,
4. use more specific Keyword  headings,
5. select specific subheadings with the Keyword  headings,
6. add in terms (using AND) to represent other aspects of the question,
7. limit the search to local holdings, publication types, year of publication, or
8. add in (using AND) the Keyword "human".

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Methodologic Filters

Methodologic filters help retrieve the best available evidence by narrowing the search to studies which have the most appropriate and rigorous study design for clinical question at hand (e.g. clinical trials for diagnosis, cohort studies for prognosis, etc.).

Methodologic filters are used in combination with a comprehensive (i.e. sensitive) Keyword or Title Word search strategy which has first been used to retrieve as much information as possible relevant to the topic .

First start with your Keyword and/or Title Word search terms and combine as appropriate. You can then limit your results to a particular methodology using one of the following strategies:

• Use Limit, then Publication Types, and then Randomized Control Trial, or
• Use Limit, then Publication Types, and then Meta Analysis, or
• Use Limit, then Publication Types, and then Controlled Clinical Trial, or
• Use Limit, then Publication Types, and then Clinical Trial.

If these do not help, here are a few advanced strategies. They can bring articles that the above methods might miss:

• Use random$ as a Title Word search term.
• Use meta-anal$ OR metaanaly$ OR meta analy$ as a Title Word search term (this takes a long time to run, but the results can surprise you).
• Use (doubl$ OR singl$) AND blind$ as a Title Word search string.
• Use clinical trials as a Keyword  search term.
• Use crossover as a Title Word search term.

And you can combine any of the above strategies together.

To increase the sensitivity of the above search you may consider adding the following:

• Use clin$ trial$ as a Title Word search term.
• Use control$ AND (trial$ OR stud$) as a Title Word search string.
• Use (singl$ or doubl$) AND blind$as a Title Word search string.
• Use placebo$ as a Title Word search term.
• Use research-design as a Keyword  search term.
• Use comparative study as a Keyword  search term.

And, of course, you can combine any of the above strategies together.

You may limit your results to Systematic Reviews using the following strategy:

• Use Limit, then Publication Types, and then Review, Acedemic.
• Use Limit, then Publication Types, and then Review, Tutorial.
• Use Limit, then Publication Types, and then Meta Analysis.
• Use systematic$ AND (review$ OR overview$) as a Title Word search string.
• Use (meta?analy$ or meta analy$) as a Title Word search term.

Or, as above, you can combine any of the above strategies together.

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