Filed at 6:30 p.m. ET

ATLANTA (AP) -- Women are five times as likely as men to die from lupus, an immune system disease that causes crippling joint pain, scientists said Thursday.

A 20-year study also found that blacks are three times as likely as whites to die from the disease, the Centers for Disease Control and Prevention reported.

Lupus turns the body's immune defense system against its own healthy tissues, in some cases attacking the kidneys and other vital organs. Many people afflicted also develop severe arthritis.

The CDC found 88 lupus deaths for every 10 million women in 1998, compared with 15 deaths for every 10 million men, said CDC lupus expert Dr. Charles Helmick.

That ratio -- with women more than five times as likely to die from lupus -- was fairly steady throughout the 20-year study, he said.

Health officials have long known lupus strikes women, particularly women of childbearing age, more often than men. Genetic factors are believed to predispose some people to the disease, and scientists are studying whether hormone imbalances may contribute.

Environmental factors such as infection, drug reactions, hormones and stress are also believed to trigger lupus. Its symptoms can be treated with steroids and chemotherapy, but there is no cure.

When broken down by race, the CDC found 137 lupus deaths per 10 million blacks in 1998, compared with 40 deaths per 10 million whites. That ratio, with blacks more than three times as likely to die from lupus, was consistent throughout the 20 years of the study, as well.

Lupus may be more deadly in blacks because of problems accessing quality health care, the CDC said.

The Lupus Foundation of America estimates that more than 16,000 Americans develop the disease each year.

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On the Net:

CDC: http://www.cdc.gov

Lupus Foundation of America: http://www.lupus.org