Lupus as a risk factor for heart disease
- Recent corticosteroid use and recent disease activity: Independent determinants of coronary heart disease risk factors in systemic lupus erythematosus?
Arthritis Care & Research, Volume 59, Issue 2, February 15, 2008, pp. 169-175
What is the topic?
People with lupus have risks for coronary heart disease (CHD), in part because they exhibit some of the "traditional" risk factors that other patients share and also possibly as a result of lupus disease activity and the medications used to treat it. (See previous article, "Accumulation of coronary artery disease risk factors over three years ...") These risks may sometimes be hard to separate out, since lupus inflammation and/or treatments may have direct or indirect effects on traditional risk factors.
What did the researchers hope to learn?
The researchers looked to see whether recent use of steroids by lupus patients and recent indications of active lupus disease were independent risk factors for CAD, and if so, how they might affect the development of other "traditional" risk factors such as cholesterol, levels, blood pressure, type 2 diabetes, etc.
Who was studied?
Researchers studied the records of 310 lupus patients who had been seen at the Montreal General Hospital Clinic over a 32-year period (1971-2003). Patients who had a heart attack, angina, stroke, or a blood clot in a vein before their first visit to the lupus clinic were not included in the study, so that a pre-existing condition would not confuse the issue of the risk factors for new events.
How was the study conducted?
The researchers reviewed the records of the patients from the time of their first visit when they were first diagnosed with lupus until either the scheduled end of the study on December 31, 2003, or the date they experienced a heart attack, stroke, or blood clot, whichever came first. In all, the researchers reviewed the records of more than 11,000 lupus patient visits over a 32-year study period, looking at blood pressure, cholesterol ("good," "bad" and total), blood sugar, and BMI ("body mass index," a measure for being overweight). They combined these measurements to give a two-year CHD risk score for each patient at each visit.
The researchers also looked at steroid use and lupus disease activity during the follow-up period. Lupus disease activity was measured with a standard disease scoring tool. Steroid use was calculated by converting all the steroid treatment into how much prednisone was equivalent and by averaging the dosing between visits if it changed between those times.
What did the researchers find?
The researchers found that, even after factoring in the possible influence of lupus disease activity, increased use of steroids in the past year was associated with increased risk factors for CHD in lupus patients. A 10 mg increase in daily steroid dose was associated with a 16% increased risk for a CHD event in the next two years. Similarly, recent lupus disease activity was also associated with higher levels of some CHD risk factors, and had a very small but real impact on immediate risk for heart attacks or strokes.
It is believed that controlling inflammation may also help reduce CHD risk, since inflammation is implicated in the development of CHD, but this research suggests that controlling inflammation with steroids increases many other CHD risk factors, such as cholesterol, blood pressure, weight gain, and type 2 diabetes.
What were the limitations of the study?
Because this study was conducted by chart review, the researchers had to estimate the steroid use over time, often relying on a chart record of a patient’s memory of what medicines they might have been taking as much as six months previously. It is quite possible that in the days between visits, lupus activity fluctuated considerably, much more than would be estimated using the disease activity scores at two consecutive visits and averaging over that time. The use of overall lupus disease activity scores also might obscure significant differences in the associations between lupus, steroid use, and CHD risk factors that could be affected by which organ systems are involved. For example, is the effect on risk factors the same regardless whether the person has inflammation in the kidney, skin, or joints?
What do the results mean for you?
This research joins a growing body of evidence that highlights the risks for heart disease that are associated with lupus, and this study suggests that both increased lupus disease activity and increased steroid usage contribute to risk. The researchers point out the need for more use of alternative anti-inflammatory treatments that can lessen the dependence on steroids.