Statistical analysis
The analysis of the research results was carried out in the EZR v.1.35 package (R statistical software version 3.4.3, R Foundation for Statistical Computing, Vienna, Austria). The Shapito-Wilk test was used to check the distribution of quantitative indicators for normality. The law of distribution differed from the Gaussian, the median value (Me) and interquartile range (QI-QIII) were given to represent quantitative indicators, the comparison of indicators in two groups was carried out according to the Mann–Whitney test. For multiple testing correction the false discovery rate (FDR) procedure was used. To analyze the dynamics of the indicators, the Friedman test was used for related samples, the posterior comparison was carried out using the Bonferroni correction. For qualitative indicators, the absolute frequency of symptom manifestation and relative frequency (%) are presented, and for the comparison of two groups, the chi-square test was used, taking into account the correction for continuity. When conducting the analysis in all cases, the critical level of significance was taken equal to 0.05.