3.3.7 Study limitations
The main limitations for randomised controlled trials are listed in Table 4.
The GDG accepted that investigator blinding in surgical intervention studies was impossible and participant blinding was also impossible to achieve in most situations. In these instances blinding was not downgraded for objective outcomes (such as mortality or re-bleeding) in quality ratings across the guideline. However, in case of subjective outcomes (for instance Quality of Life scores if reported) evidence from non-blinded trials was downgraded for study limitation since subjective scores would be prone to be influenced by blinding regardless of whether or not the study design made blinding possible or not.