Risk of bias of included studies.

<p>The responses for each question in this risk of bias tool are represented by different colors, segmented along a horizontal bar. Light gray depicts the percent of studies responding with the smallest risk of bias. Medium gray depicts the percent of studies responding with a moderate or unclear risk of bias. Dark gray indicates the greatest risk of bias. The responses to “Concealed treatment allocation?” are adequate, inadequate and unclear. The responses to “Double-blinded?”, “Intention-to-treat?” and “Interim/preliminary analysis not done?” are yes, unclear and no. The responses to “Withdrawals/dropouts described” are yes, no or partial. The responses to “Total lost to follow up <10%” are yes, no or not reported. The responses to “Funding?” are government, private or mixed/other funding sources.