Fig. 2

The search results and selection procedure. Two hundred thirty-five relevant citations were identified from the databases according to the literature search strategy described earlier. After deleting 180 duplicates, we obtained 55 studies. Based on screening titles and abstracts of the 55 remaining articles, 38 irrelevant clinical studies were excluded. By reading the 17 full-text articles, we excluded another 5 articles. Finally, we identified 1231 patients assessed in 12 articles