Table 1.

Search terms used in the primary literature search.

Databases	Specific search terms used
MEDLINE using Pubmeda; EMBASEb; Cochrane Database of Systematic Reviews	Protocol violation
	Recruitment violation
	Enrolment violation
	Recruitment error
	Protocol error
	Enrolment error
	Protocol adherence
	Protocol compliance
	Recruitment adherence

^aEach of the terms were crossed (Boolean AND) with the Medline strategy described by Haynes et al. [4] for detecting RCTs. In addition, each was also crossed with the MeSH term 'clinical trials as topic'.

^bEach of the terms were crossed (Boolean AND) with the EMBASE strategy described by Wong et al. [5] for detecting RCTs.