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Systematic Reviews for Health: 6. Phrase Searching, Wildcards and Proximity Operators

A guide on how a Research Librarian can help you during a systematic review process

Step 6. Phrase Searching, Truncation, Wildcards and Proximity Operators

These advanced search techniques can help make your search more specific and efficient. The offering of these techniques and their functions differ greatly between databases. It is therefore important to become familiar with them before you search by visiting a database's Search Help menu or see

Advanced Search Techniques


Phrase searching

Phrase searching allows users to search for articles containing a phrase rather than containing a set of keywords in random order. For most databases the phrase needs to placed in double quotation marks; e.g. "skin cancer". This is particularly useful if the words on their own are common.

NOTE!  Ovid databases search for multiple words as a phrase automatically. You do not need to use quotation marks. This is also true for PubMed, IF you search the terms in a particular field, e.g. skin cancer[Title/Abstract]. Therefore, if you do not want to search for multiple words as a phrase, you need to use the AND operator, e.g. skin AND cancer.


Truncation is a technique that broadens your search to include various word endings. To use truncation, enter the root of the word with the truncation symbol at the end.

E.g. genetic* finds genetic, genetics or genetically

WORD OF CAUTION!  Apply truncation with caution. It may cause an excessive number of irrelevant variants, especially if the root of the word is short or common. Also, the search could even be incomplete. PubMed only searches for the first 600 variations; e.g. a search for 'therap*' would not find 'therapy' as it falls outside the first 600 variants.


A wildcard character can be used to substitute for any other character or characters in a string. This is useful if a word is spelled in different ways but has the same meaning, e.g. American/British spell variants.

E.g. in Ovid: wom#n finds woman or women; col?r finds color or colour

Proximity Operators

Proximity operators are sometimes called adjacency operators. They function as precision-maximisers as they enable you to define how closely you want your search terms to be found in relation to one another.


Review all free-text terms in your Concept Table, and decide whether it would be useful to use phrase searching, wildcards and proximity operators.

NOTE!  Not all databases offer proximity operators and the wildcards differ between databases.

This is the Concept Table for Medline via Ovid.

Ovid offers a wider range of wildcards than PubMed and it also uses proximity operators.

Concept 1 Concept 2 Concept 3 Concept 4






exp Dementia/

Animal adj2 therap*3.ab,kf,ti.

Animal adj2 activit*.ab,kf,ti.

Animal adj2 intervention*.ab,kf,ti.

Pet adj2 therap*3.ab,kf,ti.

Dog adj2 therap*3.ab,kf,ti.

Canine adj2 therap*3.ab,kf,ti.


Animal Assisted Therapy/ 





Bonding, Human-Pet/

Animals, Domestic/




Auditory stimulat*.ab,kf,ti.


Music Therapy/

Acoustic Stimulation/




Apathy inventory.ab,kf,ti.

Cornell scale.ab,kf,ti.

Cohen Mansfield.ab,kf,ti.




exp Aggression/

exp Personality Inventory/

Psychomotor Agitation/


Unlimited right-hand truncation
e.g. stimulat* picks up stimulation, stimulated, stimulus

Limited right-hand truncation restricts the number of characters following the word
e.g. therap*3 picks ups therapy and therapies, but not therapeutic

The optional wild card character stands for zero or one characters within a word or at the end of a word. It is useful for retrieving records with British and American spelling variations because it finds words whether or not the extra character is present.
e.g. behavio?r picks up behavior and behaviour

Proximity Operators

ADJn is a positional operator that lets you retrieve records that contain your terms (in any order) within a specified number (n) of words of each other. To apply adjacency, separate your search terms with the ADJ operator and a number from 1 to 99. Adj2
finds terms in any order and with one word (or none) between them.
e.g. animal adj3 therapy picks up animal therapy, animal based therapy, animal assisted play therapy, therapy using animals.

This is the Concept Table for Medline via PubMed.

PubMed allows truncation searching, in which an asterisk can substitute variant endings. Since November 2022 it also allows proximity searching. This has not yet been reflected in the below search strategy.

Concept 1 Concept 2 Concept 3 Concept 4

Dementia [tiab]

Alzheimer [tiab]

Huntington* [tiab]

Kluver [tiab]

Lewy [tiab]

Dementia [mh]

Animal-assisted therapy [tiab]

Animal-assisted activit* [tiab]

Animal-assisted intervention* [tiab]

Animal therapy [tiab]

Pet therapy [tiab]

Dog therapy [tiab]

Dog-assisted therapy [tiab]

Canine-assisted therapy [tiab]

Pet-facilitated therapy [tiab]

Aquarium [tiab]

Animal Assisted Therapy [mh:noexp]

Pets [mh]

Dogs [mh]

Cats [mh]

Birds [mh:noexp]

Bonding, Human-Pet [mh]

Animals, Domestic [mh:noexp]

Music therapy [tiab]

Music* [tiab]

Singing [tiab]

Sing [tiab]

Auditory stimulat* [tiab]

Music [mh]

Music Therapy [mh]

Acoustic Stimulation [mh]

Singing [mh]

Aggression [tiab]

Neuropsychiatric [tiab]

Apathy inventory [tiab]

Cornell scale [tiab]

Cohen Mansfield [tiab]

BEHAVE-AD [tiab]


Behavior* [tiab]

Behaviour* [tiab]

Aggression [mh]

Personality inventory [mh]

Psychomotor agitation [mh]


Unlimited right-hand truncation
e.g. stimulat* picks up stimulation, stimulated, stimulus

Proximity Operators

"search terms"[field:~N]
This syntax allows you to search for multiple terms appearing in any order within a specified distance to one another:

  • Search terms = two or more words enclosed in double quotes
  • Field = search field tag for [ti] or [tiab], no other search field supported
  • N = maximum number of words that may appear between your search terms.

e.g. "animal therapy"[tiab:~2] picks up animal therapy, animal based therapy, animal assisted play therapy, therapy using animals.

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