**4. Stastistical methods**

The standard box-and-whisker plots were used for graphical representation of the parameter distribution in the particular groups of patients (Rousseeuw et al., 1999). Normality of data was verified by the Lilliefors test (Conover, 1999). To compare the observed parameters, the parametric method unpaired Student's group t-test was used (Kirkwood, 2003; Dušek, 2009). As the non-parametric statistical methods we used the Kruskal - Wallis H test and the Kolmogorov-Smirnov test. (Gibbons and Subhabrata, 2003)
