2.2 Study selection
All included studies were reviewed independently by two investigators (Z.W. and X.L.), and the results were reviewed by the third investigator (D.Z.). The inclusion criteria were restricted to (1) observational studies (cohort studies, case-control studies and cross-sectional studies); (2) the exposure of interest was hysterectomy; (3) the outcome of interest was CVD or its subordinate diseases; (4) hazard ratio (HR ) or odds ratio (OR ) or risk ratio (RR ) and 95% confidence interval (95% CI ) were available; (5) the controls were women without hysterectomy; (6) the most recent and complete article was adopted when data were duplicated in more than once for the same outcome.