Data analysis
We performed a meta-analysis, using a random effects model, if at least
three studies reported on the outcome of interest. Odds ratios (OR) and
95% confident intervals (CI) comparing women with liver cirrhosis to
controls were calculated. A p-value <0.05 was considered
statistically significant. We used the I2 for testing
statistical heterogeneity. 16 Sensitivity analyses
were performed when the I2 test showed evidence of
high heterogeneity, corresponding to I2>75%. We performed sensitivity analyses by removing
contributing papers from the analysis that were thought to be
responsible for heterogeneity based on deviating study design, case
definition, study population and etiology of liver cirrhosis. We used
The Cochrane Manager Reviewer (REVMAN 5) 17 for the
statistical analysis.
To analyze decreases of maternal mortality and variceal hemorrhage we
calculated the odds ratio of the total events that occurred, after
dichotomizing the odds ratios from studies conducted before and after
the median of total study period of all included studies. Also, we made
time sequenced plots to visualize the decreases of maternal mortality
and variceal hemorrhage. We used the median date of inclusion of
individual studies as the value on the X-axis and the incidence rates as
value on the Y-axis.