“…Of the 16 studies that were evaluated with the NIH assessment tool (NHBLI, NIH) for prestudies and poststudies with no control group, 18,19,21,22,26,29,33,34,36,38,47,49,53–56 more than half were assessed to be at low risk for bias (n = 9/16, 56%) 21,26,29,33,34,36,38,47,54 . Twenty-eight studies additionally were evaluated using the appropriate CASP tools 17,20,23,25,27,30–32,35,37,39,40,43,44,46,48,50–52,55,57–64 . Eleven of these studies (11/28; 39%) were found to have a low risk of bias 17,23,31,32,37,40,43,46,48,51,55 .…”