1 Introduction
Hysterectomy is a common surgery in women especially for benign gynecological diseases owing to its low perioperative morbidity and definite therapeutic effect.1, 2 Although in recent years, endometrial ablation has become mature gradually, it cannot completely replace hysterectomy because the re-operation rates after endometrial ablation including repeat ablation and hysterectomy increase progressively over time.2 Studies have shown that hysterectomy is associated with increased risks of many diseases, such as bipolar disorder3, fallopian tube prolapse4, osteoporosis5, dementia6 and colorectal cancer7. In addition, the association between hysterectomy and the risk of cardiovascular disease (CVD) was found.8-16
In the 19th century, the incidence of coronary artery disease (CAD) was found higher in male than female.17-19 Researchers later confirmed that male predominance depended on age20 and it disappeared in people over 60. Meanwhile, it was found that the serum cholesterol of women over 50 years old was significantly higher than that of young women.21, 22 It was speculated that this phenomenon was due to the ovarian involution after menopause. Therefore, many observational studies assessing the association between oophorectomy and CAD were conducted, regardless of the influence of hysterectomy.23 In the process of exploring this problem, negative effects of hysterectomy on CAD and other cardiovascular diseases were recognized.17, 23
Although a lot of researches were conducted, the epidemiological evidence of the relationship between hysterectomy and CVD is controversial.10-14, 16, 24-27 Since hysterectomy leads to ovarian failure by interfering with blood and nerve supply of the ovaries, some studies showed hysterectomy would increase the risk of CVD.10-14, 16, 28-30 However, Some researchers found hysterectomy was not associated with risk of CVD.24-27They considered that the increased CVD risk may because of the more adverse initial risk of CVD rather the hysterectomy itself.24-26, 31 Therefore, we conducted a meta-analysis to assess: (1) the relation between unclassified hysterectomy and risk of CVD; (2) the relationship between hysterectomy with ovarian preservation and risk of CVD; (3) the association between hysterectomy with oophorectomy and risk of CVD; (4) whether the age of hysterectomy will influence CVD risk.