There are regional differences in the English language, and, while Cochrane reviews use both British (i.e. UK) and American (i.e. US) English, individual reviews must be consistent and use only UK or US English throughout.

The ‘-ize’ suffix (e.g. randomize) is often associated with US English and ‘-ise’ (e.g. randomise) with British English, when in fact ‘-ize’ is also commonly used in British English. Cochrane reviews can use either spelling but the choice should be applied consistently within a single Cochrane review or document.

Note that the Cochrane brand guidelines state a preference for UK English with '-ize' spelling.