Statistical Analysis
All data were analyzed by IBM SPSS Version 21.0 (IBM, Armonk, NY, USA),
and the survival package in R was used for drawing plots of survival
analysis. Continuous variables were compared using Student t-test and
Mann-Whitney’s U test for normally and non-normally distributed data,
respectively. Categorical variables were analyzed using the Pearson
chi-squared (χ2) or Fisher exact probability test. The Kaplan-Meier
method was used to compute cumulative livebirth rate curves (1-survival
function) between the two groups, and the differences were compared
using a log-rank test. The date of entry for each patient was the date
of surgery. The last day of analysis was the date of the first delivery
or the last follow-up visit in women who remained non-livebirth. Women
who had no event at the end of the analysis were recorded censoring
data. We processed a Cox proportional hazards regression model with
potential variables in an enter fashion to identify predictors of
successful live birth. The magnitude of statistical significance was
expressed with adjusted hazard ratios (AHR) and 95% confidence
intervals (CI). Two-tailed P-values < 0.05 were considered
statistically significant.
Initial analysis was by intention-to-treat (ITT). We also performed a
per-protocol (PP) analysis in which we ruled out 8 patients who had
additional bilateral salpingectomy for recurrent hydrosalpinges or for
EP.