Key Points

• The 5-year survival rate of SLE patients is 90%.

• The female/male ratio is 2:1 before and 4:1 after puberty.

• Four of 11 criteria are needed for SLE diagnosis.

Systemic lupus erythematosus is a generalized autoimmune disease of unknown cause characterized by the production of antibodies to numerous antigens. The most common antibodies found in SLE are those directed against the cell nucleus (ANAs). These antibodies bind DNA, RNA, nuclear proteins, and protein-DNA or protein-RNA complexes. Antibodies to double-stranded DNA and an RNA-protein complex called Sm are found almost exclusively in SLE. Immune complex deposition results in inflammation and vasculitis, causing multiorgan pathology.

Systemic LE is most common in women of reproductive age (15-40 years), and the female/male ratio is approximately 2:1 before puberty and 4:1 after puberty. However, SLE can be seen in all ages, including infants and older adults; in these two subpopulations, the female/male ratio is only 2:1. SLE affects approximately 1 in 1000 to 2500 in the general population, but disease incidence in African American and Latino women is much higher (up to 1 in 250 in African American women ages 18-65 years). The 5-year survival after diagnosis is 90%.

Systemic LE also shows a strong familial tendency. An association with MHC genes DR2, DR3, DR4, and DR5 has been found. As with other rheumatologic diseases, SLE appears to result from a genetic abnormality that can be triggered by environmental factors. Some of these hypothesized factors include infections, stress (neuroendocrine changes), exposure to sunlight, diet, and toxins, including drugs. In addition to autoantibody production, SLE involves immune cell (B, T, monocyte) abnormalities. Because of the wide variety of presentations, ACR created a classification system to standardize the diagnosis of SLE (Box 32-3). To confirm a diagnosis of SLE, patients must have at least 4 of 11 criteria present either serially or simultaneously.

Box 32-3 Criteria for Classification of Systemic Lupus Erythematosus"

1. Malar rash. Fixed erythema, flat or raised, over the malar eminences, tending to spare the nasolabial folds.

2. Discoid rash. Erythematous raised patches with adherent keratotic scaling and follicular plugging; atrophic scarring may occur in older lesions.

3. Photosensitivity. Skin rash as a result of unusual reaction to sunlight, by patient history or physician observation.

4. Oral ulcers. Oral or nasopharyngeal ulceration, usually painless, observed by a physician.

5. Arthritis. Nonerosive arthritis involving two or more peripheral joints, characterized by tenderness, swelling, or effusion.

6. Serositis a. Pleuritis—convincing history of pleuritic pain or rub heard by a physician or evidence of pleural effusion or b. Pericarditis—documented by electrocardiogram or rub or evidence of pericardial effusion.

7. Renal disorder a. Persistent proteinuria higher than 0.5 g/day or higher than 3+ if quantitation not performed or b. Cellular casts: may be red cell, hemoglobin, granular, tubular, or mixed.

8. Neurologic disorder a. Seizures—in the absence of offending drugs or known metabolic derangements (e.g., uremia, ketoacidosis, electrolyte imbalance) or b. Psychosis: in the absence of offending drugs or known metabolic derangements (e.g., uremia, ketoacidosis, electrolyte imbalance).

9. Hematologic disorder a. Hemolytic anemia—with reticulocytosis or b. Leukopenia—less than 4000/mm3 total on two or more occasions or c. Lymphopenia—less than 1500/mm3 on two or more occasions or d. Thrombocytopenia—less than 100,000/mm3 in the absence of offending drugs.

10. Immunologic disorder a. Positive lupus erythematosus cell preparation or b. Anti-DNA: antibody to native DNA in abnormal titer or c. Anti-Sm: presence of antibody to Sm nuclear antigen or d. False-positive serologic test for syphilis known to be positive for at least 6 months and confirmed by Treponema pallidum immobilization or fluorescent treponemal antibody absorption test.

11. Antinuclear antibody. An abnormal titer of antinuclear antibody by immunofluorescence or an equivalent assay at any point in time and in the absence of drugs known to be associated with "drug-induced lupus" syndrome.

From Tan EM, Cohen AS, Fries JF, et al. The 1982 revised criteria for the classification of systemic lupus erythematosus (SLE). Arthritis Rheum 1982;25:1271-1277, with permission of the American College of Rheumatology.

*The proposed classification is based on 11 criteria. For the purpose of identifying patients in clinical studies, a person is said to have systemic lupus erythematosus if any four or more of the 11 criteria are present, serially or simultaneously, during any interval of observation.

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