Assessing the risk factors for heart disease
- Accumulation of coronary artery disease risk factors over three years: Data from an international inception cohort
Arthritis Care & Research, Volume 59, Issue 2, February 15, 2008, pp. 176-180
What is the topic?
Coronary artery disease (CAD) is a serious condition characterized by the buildup of fatty deposits called plaque along the inside walls of arteries that supply blood to the heart. This build-up of plaque is known as atherosclerosis, and is commonly referred to as "hardening of the arteries." These plaques can narrow the opening through which the blood flows and also make the artery walls stiff and less flexible than normal. The result can be a severe restriction in the amount of blood that is supplied to the heart tissue, which needs the oxygen and other nutrients that the blood carries to survive. Serious CAD can result in a heart attack, in which the circulation and nourishment to one or more areas of the heart is completely cut off.
Certain conditions and behaviors, including high blood pressure, high cholesterol, type 2 diabetes, and smoking, increase a person’s risk for developing CAD. These are often referred to as "traditional" or "classic" risk factors for CAD. People with lupus may have additional risks for developing premature atherosclerosis, either from inflammation in the blood vessels or as a side effect of some of the medications they may take.
What did the researchers hope to learn?
The researchers have an ongoing study to explore reasons why people with lupus are at risk for CAD and to differentiate those with increased risks from other lupus patients who may not be at increased risk. In particular, they wanted to see how the “classic” risk factors for CAD influence the risk over time as compared to the effects of treatments and lupus activity. By sorting out these risk factors and understanding how much impact each has on risk, better prevention of future heart attacks and strokes can be addressed for people with lupus.
Who was studied?
This research was undertaken by the Systemic Lupus International Collaborating Clinics (SLICC), a collaboration of 27 lupus treatment centers in 11 different countries in North America, Europe, and Asia. This group has developed a registry of patients from around the world, who enter the study when recently diagnosed with lupus. Each patient in this study will be followed for a minimum of 10 years and will receive standard of care from expert doctors; in this way, the risk factors for atherosclerosis will be tracked into the future.
This current report evaluates 935 patients who were enrolled over a six-year period into this registry. Each of the patients entered the study within 15 months of their initial diagnosis of lupus; on average, patients were enrolled within 5 months of their diagnosis. A total of 278 of these patients had completed three years of follow-up by the time of this report, and they made up the main study population. Of these 278 patients, 84.5% were women; 52.9% were Caucasian, 14.4% of African descent, 16.9% Hispanic, 12.9% Asian, and 2.9% other. Since this is an international study, there were a higher percent of people with Asian descent and fewer of African descent included than is typically found in lupus studies done just in the United States. The SLICC researchers hope to keep enrolling patients into the registry until more people of each ethnic group are being studied for these factors.
How was the study conducted?
When each patient was enrolled in the registry, the researchers recorded information on classic CAD risk factors, including hypertension ("high blood pressure"), high cholesterol, smoking, type 2 diabetes, post-menopause status, BMI ("body mass index," which is a measure for being overweight), waist/hip ratio, low physical activity level, and family history of CAD. Many features more related to possible lupus-specific risks were also looked at, including medications taken and various ways in which lupus has affected the patients, such as whether or not a patient has had kidney involvement. Changes in these features were tracked over three years.
What did the researchers find?
In earlier studies, the researchers had found that a substantial number of lupus patients (approximately one-third) had one or more classic CAD risk factors at the time of their diagnosis or in the first year of their disease. In fact, other studies have suggested that smoking, one of the classic risk factors for atherosclerosis, may also increase the risk of developing lupus in the first place.
In this study the researchers showed that patients continued to develop risk factors over time. Looking at the classic risk factors, at enrollment, 109 patients had high blood pressure; by the end of the three-year follow-up, that number was 162; high cholesterol was noted in 101 patients at enrollment, that number was 167 three years later; the number of individuals who smoked climbed from 104 at enrollment to 116 in the three-year period; the number of those with type 2 diabetes went from 9 to 14 during the three years. There were similar or even greater increases in BMI, waist/hip ratio, low physical activity level, family history of CAD, and nephrotic syndrome (a sign of major kidney involvement).
The number of patients taking steroids increased from 196 at enrollment to 220 after three years of follow-up; those using antimalarials increased from 166 to 215; and those using immunosuppressive drugs increased from 106 to 166. Because the increase in the number of those taking steroid was relatively small, the researchers felt that steroid use could not account for the increase in atherosclerosis risk, suggesting instead that lupus disease activity could have a higher impact. The way this will be determined is to see, over time, whether patients who have more aggressive treatment with immune suppression or who stay on antimalarials in and out of flares have decreased risk for atherosclerosis-related events, as compared to those who elect a "less is more" approach to treatment (i.e., take fewer medications).
As for treatment for classic CAD risk factors, the researchers noted that hypertension usually was well treated in lupus patients, but that high cholesterol often went untreated by physicians.
What were the limitations of the study?
This was a prospective study, meaning that the researchers decided in advance all the information they would collect and then were able to gather those data in real time. However, it will take many years before this study can get definitive answers, which rely on large numbers of patients and tracking outcomes of heart attacks, strokes, and other clear-cut signals of progressive atherosclerosis. On the other hand, the researchers are already obtaining valuable data about risks for various lupus manifestations that occur over the first three years after diagnosis, and about treatments for lupus by expert centers around the world that can be used to contribute to a standard of care for patients.
What do the results mean for you?
This study reinforces earlier findings that lupus patients are likely to have significant risk factors for CAD -- many of which are potentially reversible -- and that some of these risk factors are present even before lupus is diagnosed. This study shows that the risk factors accumulate quickly, with some impact possible just from the lupus disease activity. The most important message for people with lupus is that most of the significant risk factors for heart disease, whether or not they arise indirectly from the inflammation of lupus or from the use of steroids, can be ameliorated in a number of ways, such as controlling diabetes, high blood pressure, or high cholesterol; stopping smoking; regular exercise; and a better diet. If people with lupus pay attention to these risk factors, it could have a high impact on their risk for later heart complications.