Table 2: Summary of methodological quality of included studies on the basis of review authors’ judgments.

Included studiesAllocation system Allocation concealmentPatient Blind
AssessorHandling of missing data

Paik et al. 2005 [21]YesYesYesNoNAUnclear
Festi et al. 1993 [25]NoNoYesNoNAUnclear
Bucci and Palmieri 1993 [26]YesYesYesYesNAUnlcear
Massa et al. 1993 [27]NoYesYesYesNAUnclear
Mas et al. 2003 [28]YesYesYesYesNAUnclear
Loguercio et al. 2003 [29]NoNoYesNoNAUnclear
Fera et al. 1993 [30]YesYesYesNoNAUnclear
Song et al. 2000 [31]YesYesYesNoNAUnclear

NA: not available.