摘要：The evaluation of risk of bias of individual studies is a critical step in the systematic review process (Bero et al., 2018). Risk of bias is com- monly defined as characteristics of the design, conduct or analysis of a study related to systematic error, or deviation from the truth, in results that assess the risk of a study over- or underestimating outcome effects (Boutron et al., 2019; Viswanathan et al., 2013) (see Box 1). Although significant progress has been made in developing tools to assess risk of bias for a variety of study types (Higgins et al., 2011; Juni et al., 2001; Katrak et al., 2004; Sanderson et al., 2007; Sterne et al., 2016), there is no consensus on optimal tools for assessing risk of bias in observational studies (Bero et al., 2018).
