Interdisziplinäres Fachgespräch „Gonarthrose“ - Deutsche ...

Prof. Hartmann, Hamburg:
Die Evidenz epidemiologischer Ergebnisse
hängt nicht allein von der guten Bearbeitung
ab, sondern auch davon, ob sie
biologisch plausibel sind. Sie zeigen z.B.,
dass mehr als zwei Meilen Gehen pro
Tag über einen Zeitraum von 1 bis 10 Jahren
etwa eine Verdopplung des Risikos
erzeugt. Das lässt den Verdacht aufkommen,
dass es hier doch eine starke Verzerrung
geben kann, denn diese Menge von
Belastung würde ich eher für ein jüngeres
bis mittleres Lebensalter als sehr positiv
für die Prävention empfi nden aber nicht
als schädigend. Vielleicht geht das gar
nicht zu erfragen, wenn die Personen
55 bis 75 Jahre alt sind. Kann das sein?
Prof. Coggon, Southampton:
First I absolutely agree with you about
biological plausibility, and I think another
thing for the non-epidemiologists is
that when you interpret epidemiological
evidence, you don’t look at one study in
isolation, because you will fi nd positive
fi ndings that occur in one study that don’t
appear in others. Often the discrepancy
is just due to chance; sometimes it is due
to bias or to confounding effects. We
looked at exposures like walking in isolation.
We didn’t take account of other
concomittant occupational exposures.
Sometimes discrepancies between studies
occur because of effect modifi cation, but
chance is a major factor. It’s a problem
with our newspapers because they focus
on only one study at the time. You have
all the time to tell people to consider the
totality of evidence. And we didn’t do the
study expecting walking for two miles a
day to carry an increased risk of the knee
osteoarthritis. I showed you the fi nding
because that is what we observed, but it is
not a consistent fi nding across the epidemiological
studies. Therefore you wouldn’t
give it the same weight that you would
the association with kneeling and squatting,
which really is the very consistent
observation. In terms of biological plausibility,
I think while it is diffi cult to do
experimental studies demonstrating physical
stresses causing knee osteoarthritis
there is quite a lot of evidence that exposures
which put increased physical
stresses on joints do predispose to osteoarthritis
– either because they increase the
overall loading or because they interfere
with the biomechanics of the joints in
some way disorts the anatomy of the joints
so that there is more stress on tissues. So
we see that in osteoarthritis of the hip and
also in osteoarthritis of the hand. There
is a study that shows that hand osteoarthritis
is more common in people who
do repetitive tasks using their fi ngers and
their hands. And there is some animal
evidence as well, I think, that you can
induce osteoarthritic changes by overloading
or repeated loading of joints. But it
is not very extensive. I think associations
with kneeling and squatting are biologically
plausible, and I think the association
with walking in this study is probably a
chance fi nding.
Prof. Schiltenwolf, Heidelberg:
Isn’t the major fl aw of all these studies
shown today that they are no longitudinal
studies, that we asked for a sort of explanatory
model of the patients’ and that of
the controls. In 2007 the Framingham
Study on physical activities and osteoarthritis
of the knees was published and
there was no evidence that recreational
physical activity develops any sort of
osteoarthritis. And they had a follow-up
of nine years – so in the longitudinal
approach to the problem the evidence is
very very low that physical activity makes
us ill.
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