Search tips

ISRCTN search
Phrasing, and keywords containing punctuation
Search operators
"Stem" searching using the "%" operator
Grouping

Searching the International Standard Randomised Controlled Trial Number Register – ISRCTN search
The content of all the trial records in the ISRCTN Register has been indexed so that they can be searched efficiently.

In order to search the ISRCTN Register:

1. Enter a keyword or phrase into the SEARCH FOR text box.
2. You may select the results to be ordered by relevance (i.e. frequency of keyword or phrase), alphabetically by trial title, by sponsor, by ISRCTN or by date. You may select 10, 20 or 50 records to appear on each results page by selecting from the MAX RESULTS pull-down box.
3. Click the SUBMIT button.

Check out the FIND TRIALS boxes (to the left of the ISRCTN pages) for additional features, such as BROWSE TRIALS BY TITLE.

General note: Certain short words such as "the", "in" and "of" are too common to be indexed and are not sought unless they are part of a phrase.

Phrasing, and keywords containing punctuation
In order to search for an exact combination of words, e.g. heart attack, the phrase should be enclosed within quotation marks: "heart attack" OR 'heart attack'.

Quotation marks are also extremely useful when attempting to search using keywords that contain punctuation, for example: hyphens, apostrophes ("beta-blockers", "Alzheimer's"). If the word or words containing the punctuation are placed between quotation marks, records containing them will be retrieved, and the keywords will be highlighted in the retrieved trial record.

Search operators
Boolean operators (AND, OR, NOT)*
Search terms may be linked using the following logical search filters or operators:

• AND: when used between two words or phrases the AND operator will retrieve all trial records containing both the words or phrases,

e.g. cancer AND radiotherapy

• OR: when used between two terms the OR operator will retrieve all trial records containing either word or phrase (or both),

e.g. aspirin OR paracetamol

• NOT: when entered before a search word or phrase, the NOT operator will not retrieve records containing that word or phrase

e.g. diabetes NOT cancer

"Stem" searching using the "%" operator
A percentage (%) operator may be used after the root of a word, so expanding the query to include all words "stemming" from that root.

For example:
random% would also find randomize(d), randomise(d), randomisation(s), randomization(s)
schizo% or schizophren% would find schizophrenia and schizophrenic
diab% would find diabetes and diabetic
encephal% would find encephalitis and encephalopathy

Grouping
Brackets (parentheses) may be used to keep together logical groupings and to ensure that the search is processed in a logical sequence, e.g. (cat OR feline) AND health.

September 2006