We tested the agreement, reliability, construct validity, and feasibility of AMSTAR through comparisons with OQAQ, the latter was a validated scale (overview quality assessment questionnaire, OQAQ) developed by Oxman and Guyatt in 1991 [6] . The OQAQ scale measures across a continuum using nine questions (items 1-9) designed to assess various aspects of the methodological quality of systematic reviews and the tenth item requires assessors to assign an overall quality score on a seven-point scale [6] .