Detecting damage to arterial walls
- Progression of carotid intima-media thickness and plaque in women with systemic lupus erythematosus
Arthritis & Rheumatism, Volume 58, Issue 3, March 2008, pp. 835-842
DOI: 10.1002/art.23196
What is the topic?
People with lupus have an increased risk for developing atherosclerosis, commonly referred to as "hardening of the arteries" (see previous articles, "Accumulation of coronary artery disease risk factors over three years ..." and "Recent corticosteroid use and recent disease activity: Independent determinants ..."). As the disease progresses, the walls of the arteries -- called the intima-media -- thicken, and the passage through which the blood flows narrows as fatty plaque deposits build up along the walls of the arteries. The narrowing of the opening starts with a detectable change in the blood vessel wall itself, called intima-media thickening (IMT). This early thickening takes place without any symptoms being present. However, IMT can be measured by ultrasound, which is a painless, non-invasive procedure that uses sound waves to produce images of physical structures inside the body. The measurement of IMT in the carotid arteries, which run along each side of the neck and carry blood from the heart to the brain, is increasingly being used to detect early signs of atherosclerosis; however, to date it has not been used in studies of people with lupus.
What did the researchers hope to learn?
In this study the researchers wanted to track the progress of atherosclerosis in women with lupus (no men were included) and to look for evidence that lupus affected the risk for developing signs of atherosclerosis. In addition, they hoped to see if measuring carotid IMT with ultrasound could serve as a clinical marker for early atherosclerosis progression in a time frame that might be useful in clinical trials of new treatments for lupus.
Who was studied?
A total of 217 women from the Pittsburgh Lupus Registry were followed for this study, regardless of whether they had previous any history of cardiovascular disease. Of the 217, 89% were Caucasian, the average age was 45 years old, and 93 (43%) had been through menopause.
For comparison purposes the study also recruited 104 women from the same area who did not have lupus. This group was similar to the 217 lupus patients in terms of age and other demographic characteristics (ethnicity, socioeconomic status, menopausal status).
How was the study conducted?
At the start of the study, each of the women in the two groups had an ultrasound test taken to measure the carotid ITM and the number and size of plaque deposits. Clinical information about risk factors for atherosclerosis was also obtained, including blood pressure, cholesterol, smoking, body mass index (BMI), triglycerides, high blood sugar/glucose intolerance. For the lupus patients, data were also obtained on additional "lupus-specific" cardiovascular risk factors: how long they had had lupus; lupus symptoms (e.g., skin rash, oral ulcers, arthritis, inflammation, kidney involvement, neuropsychiatric, blood disorders); creatinine blood levels (an indicator of kidney involvement); lupus disease activity scores; antiphospholipid antibodies; complement levels; and medications. The carotid ultrasound tests were repeated at the follow-up visit, which on average was 4.2 years after enrollment for the lupus patients versus 4.9 years for the non-lupus participants.
The researchers compared the changes in carotid IMT and plaque between the two groups of women and factored in the effects of both the traditional and the lupus-related clinical risk factors for atherosclerosis.
What did the researchers find?
A higher percentage of those with lupus had carotid plaque deposits at the initial visit (31%) and at follow-up (40%) than those without lupus (17% and 20%). The lupus patients’ plaque deposits also increased over time more frequently than those without lupus. However, for the majority of lupus patients (68%) there was no change in the size or number of plaques. Thus it seems likely that more women with lupus develop plaque deposits than healthy women in their age range, and that the plaque deposition may be progressing faster.
Some lupus-specific factors seemed to be having an impact on which women with lupus are actually at risk. After adjusting for traditional risk factors, high serum creatinine (a measure of impaired kidney function) was significantly associated with ITM progression.
What were the limitations of the study?
This study looked at lupus patients at two distinct points in time -- the initial visit and the follow-up visit several years later. It was not designed to take into consideration any changes in the patients’ conditions that might have occurred in the intervening years, such as flares or changes in medications, and it is certainly possible that those events could have affected the progression of the carotid IMT and plaque accumulation.
What do the results mean for you?
The researchers point out that this study was the first to demonstrate that the progression of cardiovascular disease in women with lupus could be measured using carotid ultrasound. This may be an important tool for doctors to use to monitor lupus patients for heart disease risk and to guide those who truly are at risk towards improved preventive treatments. In addition, the study points to the possibility that carotid IMT may be a useful measurement in clinical trials to study the impact of new lupus treatments on this important early indicator for heart disease risk.
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