Surprise results from a large case-control study have shown that rheumatoid arthritis (RA) patients' disease activity does not explain their increased risk of cardiovascular disease (CVD).
"Because systemic inflammation seems to have an important effect on the generation of atherosclerosis and CVD in RA, it may be expected that the extent of inflammation is associated with the occurrence of CVD," reason Beáta Radovits (Radboud University Nijmegen Medical Centre, The Netherlands) and co-workers.
"Multiple studies found that RA patients have a greater intima-media thickness of the common carotid and/or femoral arteries than healthy controls and there is ample direct evidence for a relationship between inflammation and occurrence of CVD in RA," they add.
To better understand the relationship between RA disease activity and CVD risk, Radovits and colleagues studied 41 individuals who had suffered a myocardial infarction (MI) after being diagnosed with RA and 181 individuals who had RA, but had not experienced an MI.
The patients who had an MI were aged 67.5 years, on average, while those without the condition were significantly younger, at an average of 56.0 years.
RA patients who had suffered an MI were also more likely to be male than those without a history of CVD, had significantly higher body mass index and serum total cholesterol concentration, and lower serum levels of atheroprotective high-density lipoprotein cholesterol.
Despite these differences, RA disease activity, measured using the 28-item Disease Activity Score (DAS28), was similar in patients with and without a history of MI, the team reports in the Annals of Rheumatic Diseases.
Indeed, the adjusted odds ratio for MI was 0.9 for those with a DAS28 value of over 4.0 compared with those with a lower DAS28 value.
"This study indicates that the level of disease activity does not increase the risk for MI in patients with established RA," the investigators conclude.
"In view of the currently available evidence, it is likely that traditional cardiovascular risk factors, as well as the chronic inflammatory processes mediate the cardiovascular risk in RA patients," the researchers suggest.
They add: "As the results of this study were a priori unexpected, replication by other studies would be valuable."