The relationship between quality scores and publish year was explored too, reviews published after 2005 had similar AMSTAR scores comparing to earlier reviews (5.98±1.51 versus 6.18 ± 1.76, P = 0.70). As the methodological quality and the reporting quality were not mutually exclusive addressing in AMSTAR [8] , we explored whether the number of pages had a positive or negative effect on the AMSTAR score, the result showed there was a statistical association between AMSTAR score and the number of pages (Spearman's rho = 0.67, P < 0.001).