We detected major regional variations in CDI incidence
and case fatality. According to a laboratory survey conducted
in 2006 and updated in 2008, the C. difficile diagnostics methodology
is rather uniform in Finland [6]. Although our material
is nationally representative, there are some regions with low
incidence but high case fatality, which may be explained by a
lower diagnostic activity. Differences in diagnostic methodology
and sensitivity of the methods may also have an effect.
Indeed, the regions with laboratories using diagnostic PCR
assays had relatively high CDI incidences (i.e. second, fifth and
sixth highest of the 21 regions). There are no accurate data
available for diagnostic activity in 2008, though in 2006 considerable
regional variation was detected [6]. The small number
of cases (and the relatively higher proportion of deaths) in
some small regions might also explain the differences.