SLESystemic lupus erythematosus
Section snippets
Epidemiology
SLE is found worldwide, with an estimated prevalence of 22–241/100,000 population. In the UK, the Caribbean and the USA, it is more common and more severe in females of African descent than in white Caucasians. In a study in Birmingham, UK, the estimated prevalence in adult women was 206/100,000 in Afro-Caribbeans, 95/100,000 in South Asians and 36/100,000 in Europeans. The incidence is higher in urban populations. In most patients, SLE develops between the ages of 15 and 50 years. The
Aetiology
The precise aetiology of SLE is unknown. It is hypothesized that, like most systemic auto-immune conditions, SLE is triggered by one or a series of external stimuli in a genetically susceptible individual. The highly skewed sex differences and the age of onset in females point to a strong hormonal influence.
Pathogenesis
There is evidence that anti-double-stranded DNA (dsDNA) antibodies are directly pathogenic and related to disease activity. Circulating immune complexes are an immunopathological hallmark of SLE. They can deposit or be formed in the skin, kidney and brain, thereby initiating an inflammatory reaction, and clearance of these complexes may be impaired in SLE patients. Immune complexes also activate complement consumption. Certain complement fragments (e.g. C3a) cause the release of
Non-specific features
Patients can present with fever, fatigue, anorexia, weight loss and/or lymphadenopathy, and often need to undergo a series of investigations, including biopsy, to exclude malignancy or infection, such as tuberculosis. Fever is associated with active disease and must be differentiated from infection. SLE patients are immunosuppressed as a result of the disease and its treatment. C-reactive protein (CRP) is usually not raised in active SLE (except in serositis and arthritis). If CRP is found to
Autoantibodies
At least 100 autoantigens have been found to be targets in SLE, but few are clinically important. Antinuclear antibodies (ANA) are positive in more than 95% of patients. Raised anti-dsDNA antibody titres were found in 61% of patients in the authors' London cohort of 401 SLE patients. Anti-dsDNA antibodies are closely related to renal disease and an increase in titre should alert the clinician to a possible flare of disease, particularly if it is associated with decreasing C3 concentrations.
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Management
Treatment of SLE should be tailored to the manifestations of the individual's disease. All treatment plans should be discussed fully with the patient and adverse effects of drug therapies explained. Current therapies have significantly improved survival (85% 10-year survival). With improved prognosis, problems related to medication (e.g. diabetes mellitus, hypercholesterolaemia) and problems related to chronic organ damage (hypertension and end-stage renal failure) must be addressed. The aims
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