Acquire

4. How do I search for the evidence?

4.1. A database search strategy

5.1 A database search strategy

A search strategy ensures that a database search will be systematic and comprehensive.

One of the best ways to learn the fundamentals of database searching is to look at an example of a search strategy and see if you can follow the rationale and logic. Once you can do this, it becomes easier to translate the basic principles to your own searches.

Have a look at the search strategy in the table below and work through it line by line to follow the logic. Some of the terms may be unfamiliar: Boolean operators, subject heading, free text. These will be explained in more detail in the next few pages of the course.

This example is based on a search on CAB Abstracts and can be revised for other databases, which may use different subject headings. You can build a similar search using the ‘Advanced’ search in PubMed or VetMed Resource.

Table 6: In [cats with naturally occurring chronic kidney disease] does [a renal prescription diet compared to normal diet] increase the [survival time] of affected cats?

Search number	Search terms used	Type of search	Comments
1	(Cat OR cats)	Free text	A free text search will find ‘cat’ or ‘cats’ anywhere in the bibliographic record (e.g. in the title field, in the journal title, in the abstract, etc.)
2	Feline*	Free text	A truncated () free text search will find any words which begin with the root word ‘feline’ anywhere in the bibliographic record. This will find ‘felines’ as well as ‘feline’. You should be careful when using truncation searches though, as a short word will find more search terms, some of which may not be relevant. For example, ‘cat’ will find ‘cat’ and ‘cats’, but also ‘cattle’, ‘catalysts’ and ‘catastrophe’.
3	Felis	Free text	A free text search will find ‘felis’ anywhere in the bibliographic record.
4	Cats/	Subject heading	Searching for the subject heading ‘cats’ should find all bibliographic records which are about cats. Some databases allow you to ‘explode’ a search – this will include narrower subject headings in your search and will combine them using OR. When searching CAB Abstracts, for example, doing an exploded search for ‘cats’ will also find ‘kittens’ and ‘feral cats’. In CAB Abstracts, the operator ‘exp’ is used before a subject heading to show it is an exploded search (e.g. here this would be ‘exp Cats/’)
5	1 OR 2 OR 3 OR 4	Combination search using ‘OR’	This search combines all the searches used above to find any records about cats, using the Boolean operator ‘OR’. This is a good way of ensuring that your search is comprehensive.
6	Chronic renal adj3 (failure OR disease* OR insufficienc*)	Free text	This free text search will find ‘chronic renal’ within 3 words of ‘failure’, or any word beginning with the root word ‘disease’ (e.g. disease, diseased, diseases), or any word beginning with the root word ‘insufficienc’ (e.g. insufficiency, insufficiencies). The database will find these in any order, anywhere in the bibliographic record. Databases use ‘proximity operators’ to find words within a specified number of words of each other. CAB Abstracts uses ‘adjn’, with 'n' being the maximum number of words apart the terms can be.
7	Chronic kidney adj3 (failure OR disease* OR insufficienc*)	Free text	This free text search will find ‘chronic kidney’ within 3 words of ‘failure’, or any word beginning with the root word ‘disease’ (e.g. disease, diseased, diseases), or any word beginning with the root word ‘insufficienc’ (e.g. insufficiency, insufficiencies). The database will find these in any order, anywhere in the bibliographic record.
8	Kidney diseases/	Subject heading	Searching for the subject heading ‘kidney diseases’ should find all bibliographic records which are about kidney disease. As with ‘cats’, you can explode your subject heading search.
9	Renal failure/	Subject heading	Searching for the subject heading ‘renal failure’ should find all bibliographic records which are about renal failure. As with ‘cats’, you can explode your subject heading search. If you did an exploded search for ‘kidney diseases’ in CAB Abstracts this would also include ‘renal failure’, so you wouldn’t need to include this separate subject heading search.
10	6 OR 7 OR 8 OR 9	Combination search using ‘OR’	This search combines all the searches used to find any records about chronic kidney disease, using the Boolean operator ‘OR’. This is a good way of ensuring that your search is comprehensive.
11	(Renal or kidney or prescription or therapeutic) adj3 diet*	Free text	This free text search will find any of the search terms in brackets within three words of any word beginning with ‘diet’ (e.g. diet, diets, dietary), anywhere in the bibliographic record.
12	Renal diets/	Subject heading	Searching for the subject heading ‘renal diets’ should find all bibliographic records which are about renal diets. As with ‘cats’, you can explode your subject heading search.
13	Therapeutic diets/	Subject heading	Searching for the subject heading ‘therapeutic diets’ should find all bibliographic records which are about therapeutic diets. As with ‘cats’, you can explode your subject heading search.
14	11 OR 12 OR 13	Combination search using ‘OR’	This search combines all the search terms used to find any records about diets, using the Boolean operator ‘OR’.
15	5 AND 10 AND 14	Combination search using ‘AND’	This search combines the previous combination searches, using the Boolean operator ‘AND’. This will now limit results to records about renal diets in cats with chronic kidney disease.