Limitations
The presented single-center study retrospectively analyzed patients from
a clinical everyday population whose grouping was based solely on
clinical assessment criteria. Thus, retrospective analysis looked for
group-specific differences in collectives that were not fully
comparable, which could result in a distorted picture. In addition, the
fundamentally limited informative value of retrospective data analyses
and observational studies should be pointed out, and last but not least,
the small and unequal case numbers of the subgroups could cause a bias.