The data will be analyzed using Statistica 10 (StatSoft Inc.). Categorical data will be presented by absolute and relative frequencies (n and %). Continuous data will be summarized by the mean, median, standard deviation, minimum and maximum. The pairwise deletion will be used for missing data. The statistical significance of differences between paired data will be calculated using Wilcoxon's signed rank test. The Mann-Whitney U test will be used to compare values between different sample groups. Correlation coefficients will be determined using Spearman's rank correlation. The results will be presented as the mean ± standard deviation. Statistical significance is defined as p<0.05