Study selection
A total of 1579 records were initially retrieved, of them 107 duplicate publications were removed. The flow diagram of detailed steps of the literature search process is illustrated in Fig1. After screening, we included 43 articles for further examination of full texts. Of these articles, 36 studies were excluded because of the following reasons: due to lack of sufficient data(n=3), duplicate of already included trial (n=2), review study(n=4), outcome of interest was not reported (n=19), not a trial of active agent of interest (n=5), nonrandomized or uncontrolled (n=2), animal study (n=1).Seven eligible trials were included in the final quantitative analysis [20-26].