Based on a critical review checklist of the Dutch Cochrane Centre proposed by MOOSE, we
systematically assessed the quality of all the studies included [28]. The key points of a qualified
study include: (i) Detailed information regarding the study population and country of origin;
(ii) a clear description of the study design; (iii) a clear description of outcome assessment; (iv)
an adequate description of miR-21 measurement; (v) a clear description of the cut-off value ofmiR-21; and (vi) a sufficient follow-up period.We excluded the studies that did not meet all six
of these points.