*4.6. Statistical Analysis*

All continuous variables (age, tumor size, I-131-dose) were expressed as mean ± standard deviation (SD). Unpaired Student´s t-test was used to compare metric variables (age, tumor size, I-131-dose). Chi-squared test was used to compare categorial variables (gender, N-Stage, uptake in whole body scan, Tg-level after TSH stimulation, TSH stimulation by rhTSH, re-therapy courses). Parameters that

showed significant influence on success rate in the univariate analysis were included in the multivariate analysis. Vice versa parameters with *p* values ≥ 0.5 were not included in the multivariate analysis. The multivariate regression model was applied to analyze prognostic factors associated with treatment success. A *p*-value ≤ 0.05 was considered statistically significant. All analyses were performed using SPSS computer software (SPSS Statistics 25, IBM).
