highly significantP < 0,05
The interpretation of the tests comparing averages, Anova, Student, Wilcoxon, Kruskal-Wallis: P < 0,05, the difference is significant (s) P < 0,01, the difference is highly significant (hs) P < 0,05, the difference is insignificant (ns) The interpretation of P values at dependence tests of factors: P < 0,05, the dependence between the two factors is significant (s) P < 0,01, the dependance is highly significant (hs) P < 0,001, the dependance is very high significant (vhs) P > 0,05, the dependance is insignificant (ns) Results The progression of sacroiliitis to degree 3-4 unilaterally or 2 bilaterally after aproximaly 2 years after diagnosing reactive arthritis in the case of the first batch of patients allowed setting the diagnosis of ankylosing spondylitis.