Table 1.

Adapted SIGN checklist.

(1)	The study addresses an appropriate and clearly focused question.
(2)	The assignment of subjects to treatment groups is randomized.
(3)	An adequate concealment method is used.
(4)	The design keeps subjects and investigators “blind” about treatment allocation.
(5)	The treatment and control groups are similar at the start of the trial.
(6)	The only difference between groups is the treatment under investigation.
(7)	All relevant outcomes are measured in a standard, valid, and reliable way.
(8)	Were the statistical tests used to assess the main outcomes appropriate?
(9)	Were those subjects who were prepared to participate representative of the entire population from which they were recruited?
(10)	What percentage of the individuals recruited into each treatment arm of the study dropped out before the study was completed?
(11)	Are all the subjects analyzed in the groups to which they were randomly allocated (application of an intention-to-treat analysis)?
(12)	Where the study is carried out at more than one site, results are comparable for all sites.
(13)	Are the distributions of principal confounders in each group of subjects to be compared clearly described?
(14)	How well was the study done to minimize bias?
(15)	Is the overall effect due to the study intervention?

Note. During the assessment of noncontrolled studies, items from (2) to (6) were not considered.