We read with great interest the article by Nieminen et al and recommend that the authors further investigate the efficacy of anterior colporrhaphy with and without a mesh. The study design was good and obtained important evidence about synthetic mesh. However, we feel that Table 2 is flawed in its statistical method.

Table 2 showed the values of the pelvic organ prolapse-quantification (POP-Q) system before and 3 years after surgery. It is well known that Ba represents the most dependent point from Aa to the cervix and that the corresponding point of posterior vaginal wall is Bp. Their ranges vary from –3 to +total vaginal length. In other words, these values for Ba and Bp are nonparametric continuous variables. In Table 2, the standard deviation of many points is more than one-half of its mean, which also indicates their nonparametric distribution.

Our recent report involved the statistical analyses of POP-Q values, and we found the nonparametric nature of these measurements. Thus, we assessed these data using the Wilcoxon’s signed rank test rather than the Student t test. Although it is a simple knowledge of statistics, a number of clinical surgeons ignore it. We hope this letter will remind reviewers or authors to take a look at the relationship between the mean and the standard deviation.