2.4. Statistical methods
Statistical analysis of the EQ-5D-5L questionnaire scores (in each of the 5 dimensions considered) was conducted using Wilcoxon rank-sum test and, alternatively, the estimated reliability parameter (together with the associated confidence intervals [CIs]). The Wilcoxon rank-sum test is a standard statistical, nonparametric test that checks whether 2 independent samples come from continuous probability distributions (populations) with the same medians. Although the original version of the test was designed to compare continuous distributions, a simple generalization is possible for applications with discrete distributions (which is the case when we try to compare the distribution of questionnaire scores reflecting the degree of the symptom tested on a scale from 1 to 5). Secondly, as an alternative, we have used the estimated reliability parameter Descriptive statistical methods were also used to evaluate the results (mean, median, maximum, minimum, and SD). Examination of the distributional form for score and time data was determined by box plots. Each box plot indicated minimal value, lower quartile (lowest 25% of data), median, upper quartile (highest 25% of data), and maximal value. Normality of data distribution was assessed by the Shapiro–Wilk test. Homogeneity of variances was estimated using the Levene test. Differences between continuous variables were analyzed by a nonparametric Kruskal–Wallis 1-way test. A paired Student 