| Evidence classification method： |
GRADE method will be used to evaluate certainty (quality) of evidence associated with the risk of gastric cancer. According to GRADE method, the quality of evidence is classified into four grades: high, moderate, low and very low. Five downgrading factors (risk of bias, inconsistency, indirectness, imprecision, and publication bias) and three escalation factors (large effect, plausible confounding, and dose response gradient) are considered in the evidence grading process. After grading the evidence, the evidence will be presented through the "summary of findings" table. |
