Statistical analysis
The sample size calculation was implemented presuming an expected objective cure rate of minimum 80 % for both patient groups. A minimum sample size of 64 patients was required for each group to detect a difference of 13% in cure rates between the two procedures, with 80% power and false non-match rate (alpha) of 0.05. Assuming a follow-up loss rate of 24% after four years, a total enrolment of 168 patients was projected.
Absolute and relative frequencies were computed for categorical variables; mean ± standard deviation for continuous variables. Statistical significance of differences between groups of patients was analyzed by a Fisher exact test for categorical variables and the Mann–Whitney U test for continuous and nominal variables. Odds ratio and its 95% confidence interval was adopted for the description of group influence on binary endpoints occurrence. The SPSS Statistics (IBM) software was used, and p < 0.05 was considered statistically significant.