In evidence-based medicine, research questions or objectives are often constructed and defined according to the PICOS principle as the beginning of a study, in which the outcome is one of the key elements. However, even in the study of the same health problem, the selection and reporting of outcome measures by different researchers are often inconsistent and incomplete. Irregular reporting of outcome indicators will affect the horizontal comparison of results between studies, and also increase the risk of selective reporting bias and heterogeneity of results, thus affecting the quality of evidence and bringing difficulties to systematic review and meta-analysis.