2.3 | Statistics
Statistical analyses were carried out using the software (SPSS v.25.0
package, IBM, Chicago, IL). Values of p ≤ 0.05 were considered
significant. Categorical variables were documented as number and the
corresponding percentage in brackets. For comparisons, the chi-squared
test was employed. If the expected values in one group was <
5, Fisher’s exact test was performed. Metric demographic, clinical, and
serological data were checked for normal distribution using the
Kolmogorov-Smirnov test and the Shapiro-Wilk test. As none of the metric
values were normally distributed, they were plotted as median and
25th/75th percentiles. For
statistical evaluation, the Mann-Whitney U test was used. For survival
evaluation Kaplan-Meier analyses with log-rank test were applied. Hazard
ratios were calculated with Cox regression.
The investigations were carried out in accordance with the ethical
guidelines of the “Declaration of Helsinki” and its amendment in
“Tokyo and Venice”. The study was approved by the ethics committee of
the Martin-Luther University Halle-Wittenberg. Informed written consent
was obtained from each patient. Before the start of the investigation
the study was registered in the German Clinical Trial Register under the
number “DRKS00015776”.