4.5 Limitations
Some limitations should be considered. Firstly, time of oophorectomy
relative to hysterectomy is an important factor on CVD
risk.10, 14 However, because of the insufficiency of
data, we did not assess the association between the different time of
oophorectomy relative to hysterectomy (having oophorectomy before
hysterectomy, having hysterectomy and oophorectomy at the same time and
having oophorectomy after hysterectomy) and the risk of CVD. Secondly,
whether hysterectomy with oophorectomy is worse in risk of CVD than
hysterectomy with ovarian preservation or not is still
controversial.26, 48 In our meta-analysis, we found a
33% increase of ischemic heart disease risk in hysterectomy with
ovarian preservation and a 31% increase in hysterectomy with
oophorectomy. A statistical test is needed to assess whether there is a
difference between hysterectomy only and hysterectomy with oophorectomy.
But due to the deficiency of the data, we cannot compare the statistical
difference between the two situations. Thirdly, moderate to high
between-study heterogeneity was found, but it was not completely
explained by subgroup analyses and meta-regressions. Presumably,
confounders were different in each study, that may be an important
determinant in the heterogeneity. And the underlying confounders may
have contributed to the heterogeneity.
5 Conclusion In summary, hysterectomy, whether the ovarian
preservation or not, might increase the risk of ischemic heart disease
and hypertension, not of stroke. Hysterectomy might increase the risk of
ischemic heart disease and stroke in women who had surgery before 50y;
in women who had surgery after 50y, the results were nonsignificant.