Jun. 01, 2010

Risk Factors for Heart Disease in People with Lupus

Risk factors for clinical coronary heart disease in systemic lupus erythematosus: the Lupus and Atherosclerosis Evaluation of Risk (LASER) study. 
Authors: Haque S, Gordon C, Isenberg D, Rahman A, Lanyon P, Bell A, Emery P, McHugh N, Teh LS, Scott DG, Akil M, Naz S, Andrews J, Griffiths B, Harris H, Youssef H, McLaren J, Toescu V, Devakumar V, Teir  J, and Bruce IN. (2010). 
Journal of Rheumatology 37: 322-329.    

What is the topic?
Although it is known that people with lupus are at greater risk for coronary heart disease (CHD), very little is known about which people with lupus really are at risk and which are not. Some studies have found that factors other than the “classic” CHD risk factors (i.e., high cholesterol or blood pressure, smoking, and a family history of CHD) may contribute to CHD risk. These include some features of lupus itself as well as some likelihood of additional risk factors from lupus treatments, especially steroids.    

What did the researchers hope to learn?
The researchers hoped to identify specific characteristics of lupus patients who develop CHD that differ from those who do not.  

Who was studied?
Medical records for 149 people with lupus were studied, about half of whom developed CHD at some point after being diagnosed with lupus. For each lupus patient with CHD who agreed to participate in the study, two “control” lupus patients, who had lupus for the same amount of time but did not have CD, were added.  

How was the study conducted?
This was a “retrospective” study, meaning that the information about the patients being studied was recorded at some point in the past. The following information was recorded for each patient, up to the time of the first CHD event (where applicable): type of lupus features a patient had, laboratory results, how much damage the lupus had caused to the patient (SLICC Damage Index), and what treatments patients had received.    

What did the researchers find?
The first CHD event in the patients occurred in an age range of 33-73. The average age was 53. More men than women with lupus developed CHD. Lupus patients having CHD were, on average, significantly older than those without CHD. Lupus patients with CHD also showed greater use of azathioprine (an immune-suppressing treatment) and were also more likely to have high blood pressure or a family history of heart disease. 

Editor’s Note: Being a man, having high blood pressure, and having a family history of heart disease are traditional and expected risk factors for heart disease.      

A body mass index (BMI) was available for some of the patients. BMI is a measurement that factors in a person’s weight and height to determine the healthiness of his/her weight. The patients with CHD had a higher BMI than lupus patients without CHD. Also, in a subset of patients, a test for kidney damage showed higher levels of “creatinine” (a test that reflects kidney damage) in patients (recorded prior to first CHD event) having CHD.    

Whether or not CHD developed did not seem to affect the clinical pattern of the lupus in terms of organ involvement. 

There were also no differences in levels of antiphospholipid antibodies, lupus anticoagulant, anti-double-stranded DNA antibodies or anti-ribonucleoprotein antibodies.  

What were the limitations of the study?
Some patient information was missing from a lot of the records, including some factors that might affect risk for CHD (such as ethnicity, family history of CHD, steroid treatments, and cholesterol levels).   

What do the results mean for you?
This study confirms that certain “classic” risk factors for CHD (i.e., high blood pressure and family history of CHD) as well as some lupus-related characteristics (i.e., azathioprine treatment, high creatinine levels), might increase CHD risk.  

Azathioprine is one of the most commonly used immune suppressants for lupus. The association of azathioprine treatment with increased risk for CHD could reflect some unknown issues relevant to this and/or all immune suppressants; or, it might suggest that patients receiving this treatment reflect a more active group of patients, with a greater tendency to have lupus flares, which might be causing the increased CHD risk. This is important to keep in mind since the risks of not taking needed immune-suppressing treatment should be weighed against the possible risks of taking it. Most importantly, since not all of the risks described here can be dealt with, it makes sense to consider all that can be done to prevent the traditional risks for CHD by not smoking, getting regular exercise, eating a healthy diet, and doing whatever is necessary to keep cholesterol levels and blood pressure under control. 

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