Diseases, like buses, tend to come in clusters. Heart
disease is frequently the unwelcome partner of a whole
range of chronic conditions. While diabetes is, of course,
the chronic disease most closely associated with heart
problems, according to new research rheumatoid arthritis
(RA) could lay claim to second place.
"Our previous research showed that
rheumatoid arthritis patients have a higher risk of
early death than others and that these deaths are mostly
due to cardiovascular disease," says Mayo Clinic rheumatologist
Dr Sherine Gabriel.
"We suspect that the systemic inflammation
that characterizes rheumatoid arthritis also promotes
cardiovascular disease and cardiovascular death, and
the goal of our research is to disentangle the complex
relationships between these two diseases," she adds.
The research conducted out of the
Mayo Clinic in Rochester, Minnesota, was published in
the March issue of Arthritis and Rheumatology. The study
found that a number of markers of inflammation in RA
are independent risk factors for cardiovascular death.
After controlling for traditional risk factors such
as smoking, alcohol, hypertension, obesity and diabetes,
an erythrocyte sedimentation rate of over 60mm per hour
was found to increase risk by a factor of two, RA vasculitis
by a factor of 2.4 and RA lung disease by a factor of
2.3.
The influence of traditional risk
factors was less than would be expected in a non-arthritic
age-matched population. "What we are finding is that
though traditional cardiovascular risk factors are important,
they're less important for those with rheumatoid arthritis,"
explains co-author Dr Hilal Maradit Kremers. "Something
else is going on. It could be that rheumatoid arthritis
and heart disease have a common origin. What we do know
is that the cause can't be explained by just one factor
— it's multifactorial."
These results are based on data
from the Rochester Epidemiology Project, which provides
a database of all the inhabitants of Rochester, Minnesota.
So the study included everyone in the town with RA,
which added up to a total of 603 subjects with an average
age of 58, of whom 73% were women.
Over 15 years of followup, 354
of these patients died and cardiovascular disease was
the primary cause of death in 176 cases. The subjects
were three times as likely as an age-matched population
to have been hospitalized for acute myocardial infarction.
Moreover, they were at five times the normal risk of
having an unrecognized heart attack, and far more vulnerable
to sudden cardiac death.
Dr Kremers explained the results
by saying, "It's possible that people suffering from
rheumatoid arthritis have so much pain in their joints
and are receiving so many painkillers that they either
don't feel the chest pain in the same way as those without
rheumatoid arthritis or don't appreciate its importance."
Arthritis Rheum Mar, 2005;52(3):722-32
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