- What is systemic lupus erythematosus (SLE)?
- Statistics on lupus
- Risk factors for lupus
- Progression of lupus
- Symptoms of lupus
- Clinical examination of lupus
- How is lupus diagnosed?
- Prognosis of lupus
- How is lupus treated?
What is systemic lupus erythematosus (SLE)?
Systemic lupus erythematosus (SLE) is an autoimmune disorder that affects a range of different organ systems within the body. It is particularly likely to affect the skin, causing a distinctive rash and the joints causing pain. However these effects are minor and SLE can also cause major damage to the body’s vital organs, including the brain, heart and kidneys. When SLE affects the vital organs it can have serious health implications and is potentially fatal.
Statistics on lupus
SLE is a rare disease, that is more common in people of African Americans and Asian ethnicity (compared to Caucasian) and women (compared to men). A study conducted in the United States reported that 5.5 new cases of SLE were diagnosed each year, per 100,000 people. Amongst women new diagnoses increased to 9.3 per 100,000. The average age at the time of diagnosis was 39.3 years, however SLE cases were diagnosed in children and the elderly. African Americans were, on average, diagnosed at a younger age than Caucasian Americans.
At any given time 73 people for every 100,000 were experiencing lupus. Ten times more women had lupus at any given time compared to men and more than twice as many African Americans compared to Caucasian Americans.
In Asia-Pacific countries 1-3 cases of lupus are diagnosed per 100,000 people each year. At any given time 4-45 per 100,000 people are living with lupus. Indigenous Australians are more likely to be diagnosed with lupus that Caucasian Australians; at any given time >90 per 100,000 Indigenous Australian has lupus compared to 19 per 100,000 Caucasian Australians. In the Asia Pacific, women are also approximately 10 times more likely to have lupus than men. People of Asian ethnicity, are on average diagnosed with the condition are a younger age (27-34.9 years in different countries) than in the United States.
Risk factors for lupus
Cause unknown but probably multi-factorial. Factors thought to be involved:
- Genetic: 70% concordance between identical twins and increased incidence of HLA-B8 and HLA-DR3;
- Immunological: antinuclear antibodies are present which are thought to result from polyclonal activation of B cells by an antigenic stimulus (possibly viral). May be associated with impaired T cell regulation and deficiencies in complement;
- Drugs: hydralazine, isoniazid, anticonvulsants and procainamide may cause a mild lupus like syndrome which often resolves with withdrawal of the drug;
- Infection: viral infections may be responsible;
- Hormonal factors: high incidence in women suggest female hormones may modify the immune system;
- Sunlight is an exacerbating factor for the cutaneous (affecting the skin) manifestations in most cases.
Progression of lupus
SLE usually occurs in episodes, with flares and remissions that may last for long periods of time. In some patients, it may persist as a chronic illness. Generally speaking, if serious complications have not developed by the first few years, they are unlikely to do so.
Symptoms of lupus
Features typical of SLE include:
- Joint pains;
- Rash that worsens with sun exposure;
- Mouth ulcers;
- Hair loss;
- Urticaria (hives).
There may have been previous problems with pregnancy (multiple miscarriages), or a family history of autoimmune disease such as rheumatoid arthritis.
Other features may include:
- Raised blood pressure;
- Mouth ulcers;
- Dry eyes;
- Hair loss;
- Joint tenderness or swelling;
- Signs of fluid in the lungs;
- Signs of inflammation of the fibrous sac surrounding the heart (pericarditis);
- Protein in the urine;
- Scaly red rash in a ‘butterfly’ distribution over the face and other sun exposed areas.
How is lupus diagnosed?
A combination of clinical and physical findings, plus appropriate tests are needed to make a diagnosis of SLE.
Tests may include:
- Blood tests;
- Immunological tests;
- Urine testing (protein in the urine suggests kidney involvement);
- Biopsy (taking a sample of the skin or kidney to look for abnormalities);
- MRI scan to look for involvement of the brain.
Prognosis of lupus
With current treatments, prognosis is good. Survival rates have increased from 50% at five years during the 1950s, to approximately 90% at 10 years presently.
How is lupus treated?
Treatment depends on symptoms and severity of the disease.
- NSAIDs – useful for mild disease with arthralgia;
- Hydroxychloroquine – mild disease when symptoms cannot be controlled with NSAIDS or for cutaneous disease;
- Corticosteroids – mainstay of treatment. Particularly for moderate to severe disease. Aim is to control disease activity before gradually reducing the dose;
- Immunosuppressives (azathioprine, cyclophosphamide) – usually in combination with corticosteroids for severe disease (e.g. renal or cerebral disease);
- Topical steroids – for discoid lupus. Should also avoid excessive sunlight (suncream and clothing).
- Jakes RW, Bae S, Louthrenoo W, et al. Systematic Review of the Epidemiology of Systematic Lupus Erythematosus in the Asia-Pacific Region: Prevalence, Incidence, Clinical Features and Mortality. Arthritis Care Res. 2012; 64(2): 159-168. [Full Text]
- Somers EC, Marder W, Cagnoli P, et al. Population-based incidence and prevalence of systemic lupus erythematosus: the Michigan Lupus Epidemiology and Surveillance program. Arthritic Rheumatol. 2014; 66(2):369-78. [Abstract]
- Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison’s Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001.
- Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.
- Hurst JW (Editor-in-chief). Medicine for the practicing physician. 4th edition Appleton and Lange 1996.
- Kumar P, Clark M. Clinical Medicine. WB Saunders 2002 Pg 427-430.
- Longmore M, Wilkinson I, Torok E. Oxford Handbook of Clinical Medicine. Oxford Universtiy Press. 2001