Table 1.

Sign 50 checklist for RCT study design  [23]

Section 1: Internal validity 1
Item	Criteria
1.1	The study addresses an appropriate and clearly focused question.
1.2	The assignment of subjects to treatment groups is randomized.
1.3	An adequate concealment method is used.
1.4	Subjects and investigators are kept blind about treatment allocation.
1.5	The treatment and control groups are similar at the start of the trial.
1.6	The only difference between groups is the treatment under investigation.
1.7	All relevant outcomes are measured in a standard, valid and reliable way.
1.8	What percentage of subjects in each treatment arm dropped out before the study was completed?
1.9	All subjects are analyzed in the groups to which they were randomly allocated (intention-treat analysis).
1.10	Where the study is carried out at more than one site, results are comparable for all sites.
Section 2. Overall Assessment
Quality Score	Criteria
++	All or most of the criteria have been fulfilled adequately or well. Where they have not been fulfilled the conclusions of the study are thought very unlikely to alter. An article receives this score if there are 0 criteria scored as poorly addressed.
+	Some of the criteria have been fulfilled adequately or well. Those criteria that have not been fulfilled or not adequately described are thought unlikely to alter the conclusions. An article receives this score if 1-3 criteria are scored as poorly addressed.
-	Few or no criteria fulfilled adequately or well (3 or more poorly addressed criteria). The conclusions of the study are thought likely or very likely to alter. An article receives this score if more than 3 criteria are scored as poorly addressed.

¹Each item is evaluated as well covered, adequately addressed or poorly addressed. Item 1.10 can also be marked as not applicable.