Myrl Jeffcoat myrlj@jps.net

8 mars, 2005 09:22

Does Lupus Discriminate?

Written by: Christine Haran -

Published on: March 3, 2005

Anyone can develop lupus, but people in certain ethnic groups are at much higher risk for this chronic autoimmune disease. This is particularly true for African-American women, who have three times the risk of white women, for example.

To look at how ethnicity influences lupus risk, the Lupus in Minorities: Nature versus Nurture (LUMINA) study was started in 1993 by researchers at the University of Alabama at Birmingham, the University of Texas-Houston Sciences Center and the University of Texas Medical Branch at Galveston. The study involves 300 African American, Hispanic and Caucasian people with lupus between the ages of 20 and 50.

In an autoimmune disease such as lupus, the immune system mistakenly attacks the body's own tissues. In lupus, antibodies can go after many different part of the body, including the muscles and bones, the skin, the nervous system, the kidneys, the heart and the lungs.

The LUMINA researchers have found that lupus behaves differently in African Americans and Hispanics than it in does in Caucasians. LUMINA researchers Graciela Alarcon, MD, MPH, the Jane Knight Lowe Chair of Medicine in Rheumatology at the University of Alabama in Birmingham, discusses some of these differences below, as well as how a combination of genetic and socioeconomic factors affect the course of the disease in these groups of people.

What is lupus?

Lupus is an autoimmune disease that occurs predominantly in women in their reproductive years. When we refer to lupus, for the most part we are referring to systemic lupus erythematosus (SLE).

Lupus is also a multi-system disease, which means it can involve many organ systems, and it may vary significantly from patient to patient. Some patients have a very mild disease in which they only have joint pain, skin rashes and fatigue while others have very serious disease that can involve the brain, kidneys or heart.

Why did you and your colleagues decided to conduct the LUMINA study?

Because this disease affects minority groups more seriously and more frequently, especially African Americans and Hispanics in this country, there was a request by the National Institutes of Health to study lupus in minorities. Most of the studies in the United States, at least, have focused on patients of African-American ethnicity. So we felt that because of the growing number of Hispanics and the fact that we were already experiencing an increased number of patients with lupus among the Hispanic population, we wanted to include the Hispanic group. That's why we got into the LUMINA study, and we are now in our twelfth year of studying these patients. So we have an African-American group, a Hispanic group and a Caucasian group.

What kinds of differences do you see between different ethnic groups?

There are several differences. The disease starts at a younger age and more abruptly in the African Americans and the Hispanics from Texas. (We are studying another Hispanic subgroup in Puerto Rico, but they tend to have disease that is a little bit different from the one in Texas. They tend to be more like the Caucasians.) So in African Americans and Hispanics from Texas, the whole disease just comes on with full force within two or three weeks, whereas Caucasians and the Hispanics from Puerto Rico may develop the disease in a more insidious manner, so the disease starts smoldering until somebody really notices it.

Patients of African-American ethnicity and Hispanic ethnicity in Texas have also more kidney disease, and therefore, they experience higher death rates. So our study is validating the idea that the disease is more serious among some minority population groups.

What might explain these differences?

It is not clear whether these differences are due to difference in the socioeconomic profile of the patients or to genetic differences. Some differences have been identified in some of the genes that control the immune process, but the differences have not been clearly established yet. But if there are genetic factors that influence the occurrence of the disease or the severity of the disease among ethnic groups, that would suggest that you would need different gene therapies for different ethnic groups. The other possibility is that you have the same genes operating in everybody, but they are influenced by the other factors such as environmental or socioeconomic factors.

Do you think it is harder to make a diagnosis in these ethnic groups? I don't think so, based on my experience. In many cases patients present abruptly with a very severe disease. It's not like just having a little bit of joint pain. In young African-American women with, for example, fever, arthritis and pleurisy—inflammation of the lining of the lungs—most physicians are going to think of the possibility of lupus. It's harder, actually, to make a diagnosis in the patient who is not that sick, because you may not think about it. Or you might not think about lupus in a man in his 60s. But in the young African-American or Hispanic woman with the right symptoms, I think it's easier for a physician to think their symptoms are caused by lupus.

How is lupus treated?

We have been using the same treatments for lupus for the last 20 years. There is a lot of excitement about new possibilities, but there's still nothing out on the market. So we still use antimalarial medication for arthritis and skin rashes; corticosteroids such as prednisone, which is always a popular anti-inflammatory; and medications such as Cytoxan and Imuran, which are immunosuppressants. You generally need to take medications continuously. Unfortunately, people don't always take their medications, and that, of course, may have a long-term impact on outcome. Not all cases of lupus are the same, so the outcome of untreated lupus all depends. For example, if you don't treat lupus that affects the kidneys, you may end up losing kidney function and going into dialysis.

How can poverty make it hard for certain groups to get the care they need?

Poverty has been consistently found to be a factor affecting survival. That means that poverty affects the probability of dying sooner with lupus. But there are other factors that are related to poverty, such as access to care. We have not been able to sort out exactly which factor is the most important, because they all are interrelated. But in some of the other analyses that we have performed, we have seen that having a poor coping style with chronic illness or having poor social support may also influence the outcome of the disease.

People need to understand that the disease is going to stay with them for the rest of their lives, that it's going to fluctuate over time, but that they need to take the medications as indicated. Unfortunately, in many cases, it's hard for the patients to come back to the hospital or to the clinic for follow-up because of socioeconomic problems such as transportation or family problems, and that may prevent them from sticking with their medications. You work with each patient individually, but there's a limit to what we can do as physicians. In some cases, the infrastructure to help these patients is not really there.

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