Similar to RA, systemic lupus erythematosus (SLE), the most common form of lupus, is an autoimmune disorder in which the immune system turns against the body and attacks healthy normal cells, causing damage to various organs. In SLE, organ and tissue damage can be widespread, affecting joints and skin, as well as kidneys, heart, lungs, and brain. SLE is more common in women and affects certain ethnic groups more than others, including women of Hispanic, African, Asian, and Native American descent. The prevalence of SLE varies widely by country and geography, affecting an estimated 40 out of 100,000 persons of Northern European descent and as many as 200 out of 100,000 persons of African descent. In the US, the total number of people with SLE is estimated at approximately 250,000.1
Although the prospects of long-term survival for individuals with SLE is better today than it has ever been, largely due to treatment breakthroughs, the likelihood that the disease will prove fatal is still high. Someone who is diagnosed with SLE at an early age (around 20 years) still faces a 1 in 6 chance of death by the age of 35. As patients with SLE age, the likelihood of dying from a heart attack or stroke increases dramatically compared with the general population. SLE is similar to RA in this respect. Systemic inflammation that occurs with both diseases is associated with increased risk for development of cardiovascular disease.1,2
SLE flares cause a range of symptoms
SLE involves periods of disease activity called flares, which range from mild to severe, in which characteristic symptoms appear. The symptoms that occur during a flare may include joint pain and/or swelling, muscle pain, fatigue, rash (most often affecting the face), hair loss, sun sensitivity, fever, chest pain upon breathing, decreased blood circulation in finger or toes, swelling in legs or face (around the eyes), ulcers in mouth, swollen glands, and less commonly, headache, dizziness, confusion, and seizures.
RA and SLE
Although SLE is not considered a common comorbidity or complication associated with RA, the two conditions do share similarities in the disease processes that affect the body. RA and SLE are among the most common rheumatic diseases of over 100 different rheumatic diseases. The chronic systemic inflammation involved in both RA and SLE affects joints and a range of other organs and organ systems. The inflammatory processes in both diseases are characterized by the presence of immune cells and chemicals in affected organs, with inflammation involving activation of T-cells, B-cell production of auto-antibodies, immune cell (macrophages and neutrophils) migration and infiltration of organs, and the production of a range of inflammatory cytokines that can lead to organ damage.3
Like RA, genetics appears to play an important role in susceptibility to SLE, but heredity is only part of the picture. The likelihood that an identical (monozygotic) twin whose brother or sister has SLE will also develop SLE is only about 24%, suggesting that some other non-genetic factor must also be at play in determining risk for SLE. Other non-genetic and environmental factors that have been examined for a possible role in increasing risk for SLE include infections, smoking, and exposure to silica (from mining operations), and exposure to certain solvents and pesticides.4