5. Statistical analysis
According to literatures 7, 8, 12, 31-33, for the
primary endpoint, we assumed that the 16-week CR rate was 25% in MA
group, 50% in LNG-IUS group and 60% in MA+LNG-IUS group; with a power
of 0.8 at a two-sided significance level of 0.05; requiring an accrual
of 362 eligible patients (lost to follow-up rate <10%), which
was too large to be carried out. Then we eventually decided to recruit
180 patients with 60 in each group as a phase II study. Modified
intention-to-treat (ITT) analyses were performed for patients underwent
endometrial evaluation at 16 or 32 weeks, and patients missed
endometrial evaluation at 16 or 32 weeks but did not reach CR at
subsequent endometrial evaluation. The latter was regarded as not
reaching CR at 16 or 32 weeks. Patients missed endometrial evaluation at
16 or 32 weeks but reached CR at subsequent endometrial evaluation were
excluded for 16 or 32-week CR rate analysis. ANOVA test or
Kruskal-Wallis test was used for the comparison of continuous variables
between the three groups, and Student’s t-test or Mann-Whitney test was
used for comparison between two groups. Chi-square test or Fisher’s
exact test were used for the differences in the categorical variable.
Time-to-event endpoints were estimated with the Kaplan-Meier method.
Log-rank test was used to compare the differences in survival curves.
Cox regression analysis was used to estimate hazard ratio for CR or
recurrence. A 2-tailed P -value of <0.05 was considered
statistical significant. All statistical analyses were performed using
SPSS for windows (version 22.0; Armonk, New York). COSORT guidelines
were consulted to outline this study 34.