Understanding How Cardiovascular Risk Factors and RA Affect Atherosclerosis
What problem was studied?
Atherosclerosis, commonly called “hardening” of the arteries, occurs when arteries are injured, swell, tear, bleed and become scarred and thickened. Two mechanisms may lead to an artery injury: the formation of plaque, a sticky substance that can clog arteries, rupture and then cause a blood clot; or inflammation of an artery’s lining, which then causes the lining to swell and trap substances that form plaque. Previous studies looked at how much atherosclerosis was present in people with rheumatoid arthritis (RA), as well as the rate of cardiovascular events, such as heart attack, in people with RA. In this study, researchers developed estimations of what effect cardiovascular risk factors have on the development of atherosclerosis and what effect RA has on the development of atherosclerosis.
What was done in the study?
Using high-resolution ultrasound, researchers – including Arthritis Foundation-funded researchers, Inmaculada del Rincón, MD, and Agustin Escalante, MD, of the University of Texas Health Science Center in San Antonio – measured the amount of plaque and the thickness of the arterial lining, called intima-media, in the carotid arteries of 631 people with RA. The ultrasound sessions were recorded onto VHS tape, and the tapes were reviewed and the severity of plaque formation and intima-media thickness were determined by three separate experts who did not know the characteristics of each patient. Statistical analyses were performed to compare demographic characteristics, such as race, age and gender, with cardiovascular risk factors – diabetes, high cholesterol, smoking (both current and ever), high blood pressure and high body mass index. Then data regarding each patient’s RA were factored in, including how long they had the disease; how many tender, swollen or deformed joints they had; the number of nodules; corticosteroid use; and results of lab tests, including level of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) and whether the person was positive for HLA-DRB1 SE (see “Protein Marker for RA?”). The impact each of these sets of characteristics had independently and combined over time on atherosclerosis was determined.
What were the study results?
Carotid plaque was most prevalent in white men older than 65. Of those who also had RA, the characteristics contributing most to carotid plaque were: longer disease duration, higher number of deformed joints, higher level of CRP and ESR and corticosteroid use. The more cardiovascular risk factors a person had, the more atherosclerosis they had. However, higher ESR values were linked to thicker arterial linings and atherosclerosis grew worse during the years people had RA only if cardiovascular risk factors were present. Researchers suggest that inflammation makes established risk factors have more of an effect, but that the mere presence of inflammation likely does not cause atherosclerosis. Researchers concluded that “the presence of cardiovascular risk factors may be necessary for systemic inflammation to promote atherosclerosis.”
What’s the relevance to people with arthritis?
This study shows that, more than ever, it is important for people with RA, as well as other inflammatory disorders, such as ankylosing spondylitis, lupus, scleroderma and reactive arthritis, to make lifestyle changes to reduce cardiovascular risk factors. Modifying such risk factors – that is, quitting smoking and lowering cholesterol and blood pressure – could help reduce the known increased risk of cardiovascular problems in people with RA.
Source: Arthritis & Rheumatism, November 2005